Originally published in The Ottawa Citizen October 05, 2005
The omega-3 (linolenic) and omega-6 (linoleic) fatty acids discussed in detail last week are the focus of many clinical trials. Have the clinical studies supported the health claims?

Several well-designed cardiovascular health studies support the hypothesis that omega-3 fatty acids like eicosapentaenoic acid (EPA) and decosahexanoic acid (DHA) have a protective effect on the heart. In the Zutphen study, men who ate fish more than once a week had significantly less coronary artery disease rates than men who rarely consumed fish.

The diet and reinfarction trial found that men with a previous history of heart attack who ate two or more fatty fish servings per week over two years had a 29 per cent reduction in all-cause mortality (the number of deaths expected per year in a population). They were compared to men with similar heart attack histories who did not eat fish.

The Lyon diet heart health trial looked at the effect of two diets in people who had recent heart attacks. One group was randomized into a Mediterranean diet rich in omega-3 fatty acids and the control group participated in the American Heart Association step-1 diet.

Although there was no improvement in cholesterol levels or body mass index in the two groups, the death rates were different. Fourteen people in the Mediterranean diet group died, whereas 59 died in the control group; a 76 per cent relative reduction in mortality.

Several studies suggest that omega-3 fatty acids improve lipid profiles. In one study, four grams of omega-3 per day reduced LDL-cholesterol levels by five to 10 per cent, increased HDL one to three per cent, and reduced triglycerides by 20 to 30 per cent. HDL is the “good” cholesterol that helps eliminate cholesterol from the body while LDL does the reverse.

Several reviews indicate modest reductions in blood pressure with increasing fish oil consumption. It had no effect on people with normal blood pressure.

There are some small studies that point to a reduction of morning stiffness and joint swelling in people with rheumatoid arthritis. These effects were observed in people taking greater daily dosages of fish oil for at least 12 weeks. Further reducing omega-6 intake seemed to reduce the chemical mediators that cause inflammation. Some patients were able to reduce their dose of anti-inflammatory medications.

In the March 23 issue of the Journal of Neuroscience, a study out of UCLA looked at DHA’s effect on Alzheimer’s disease progression.

Mice were genetically altered to develop Alzheimer’s disease. One group was fed DHA-fortified feed and the control group had a normal diet, or a DHA-depleted diet.

The DHA-fed mice had 70 per cent less buildup of amyloid protein in the brain over a three- to five-month interval (equivalent to several human years).

Another study by the same group published in Neuron in the fall of 2004 showed that DHA protected the brain cells communication areas (synapses). These mice performed better on memory tests.

People eating fatty fish should be aware of the contamination risk from polychlorinated biphenyls (PCBs), methylmercury, dioxins, and other environmental contaminants. They can accumulate in certain fish such as king mackerel, shark, swordfish and tilefish. Health Canada advises Canadians to “limit consumption of these fish and fresh and frozen tuna, to one meal per week.

“Pregnant women, women of child-bearing age and young children should eat no more than one meal per month.”

Shrimp, canned light tuna, salmon, pollock and catfish are low in mercury. Albacore (white tuna) has more mercury than canned light tuna and should be limited to less than six ounces per week.

A survey published in 2004 in the journal Science (Hites RA, Foran JA, Carpenter DO, Hamilton MC, Knuth BA, Schwager SJ. Global assessment of organic contaminants in farmed salmon. Science 2004;303:226-9) found that farmed salmon has significantly higher levels of polychlorinated biphenyls and other organochlorine contaminants than wild salmon. Researchers disagree about how much farmed salmon consumption is safe. These contaminants are usually not found in high-quality fish oil supplements.

It is always preferable to get our nutrients from food. Foods other than oily fish that are a good source of omega-3 fatty acids include oils (canola, walnut, fish and flaxseed), green leafy vegetables, nuts, seeds and beans.

Although well-tolerated, some common side effects of fish oil supplements are dose dependent; a fishy aftertaste and gastrointestinal effects like nausea, bloating and belching.

.

Related articles:

1. The skinny on omega-3 fatty acids
2. Consuming the nutrients you need
3. For a healthier diet, just skip the latest fad

Originally published in The Ottawa Citizen September 28, 2005
Our diet has radically changed over the past century, and with it the balance between two essential omega fatty acids, omega-3 (linolenic acid) and omega-6 (linoleic acid). An essential nutrient is one that the body cannot make for itself or cannot manufacture enough of on its own.

We now consume more grain-fed fish and animals, vegetable oils (corn, safflower, sunflower and cottonseed) high in omega-6 fatty acids, and fewer vegetables and eggs. Most margarine and many packaged baked goods contain trans-fatty acids or hydrogenated oils that block the body’s ability to convert the omega fatty acids into other important nutrients.

Our dietary balance of omega-6 to omega-3 fatty acids has shifted from an estimated 1-3:1 a century ago to approximately 10-14:1 in the typical North American diet today. In other words, instead of consuming equal amounts of omega-6 and omega-3, we are now consuming between 10 to 14 times more omega-6. This imbalance can cause health problems.

Why are people paying more attention to omega fatty acids and the dietary balance shift? The omega-3 fatty acids seem to have several important properties: they reduce inflammation, prevent heart arrhythmias, dilate blood vessels and have anti-clotting capabilities.

Omega-6 fatty acids do just the opposite; they promote an inflammatory response and encourage clotting.

The human body requires all of these processes to function well but the dietary balance now favours the omega-6′s. Food scientists continue their research studying the effects this might have on heart and inflammatory diseases, among others.

We know that breast milk rich in nutrients like arachidonic acid (ARA) and decosahexanoic acid (DHA), derived from the omega-6 and omega-3 fatty acids, respectively, accumulate in every organ and cell in the body and promote infant brain and eye development. Indeed, at specific nutrient levels, babies have better co-ordination, problem-solving skills and sharper vision.

A worldwide study looking at the breast milk concentration of DHA and ARA found a wide range of values. Women in societies consuming large quantities of fish had the greatest concentration of these breast milk nutrients.

A growing body of scientific research seems to implicate omega-3 fatty acid deficiency with an increased incidence of common diseases such as heart disease, Crohn’s disease, asthma, Alzheimer and certain kidney diseases, among others.

Observational studies that looked at the health outcomes of a Mediterranean diet seemed to point to a lower risk of coronary artery disease and certain cancers. Although many countries border the Mediterranean Sea, each with populations that have varied diets, there are common dietary threads: use of olive oil, raw fruits and vegetables, bread and cereals, potatoes, nuts and seeds, little to no red meat or eggs, low to moderate consumption of fish, chicken and wine.
This geocultural difference is important when one considers it is a diet lower in saturated and trans-fats than our North American “super-size” menu. It goes the heart of how it alters the body’s ability to processes these nutrients.

The granddaddy of the omega-3 fatty acids is a compound called alpha-linolenic acid (ALA). It is found in oils (canola, walnut, fish and flaxseed), green leafy vegetables, nuts, seeds and beans.

The body uses specific enzymes to convert ALA into eicosapentaenoic acid (EPA) and DHA. Research indicates that EPA and DHA confer the health benefits associated with the omega-3 fatty acids.

Consider these enzymes as a series of assembly lines bringing the product from processing station to processing station. ALA and linoleic acid use the same initial assembly line before they split up and travel down their own manufacturing line.

When more linoleic acid is consumed than ALA, the former prevents the ALA from being processed. This common assembly line or enzyme is the rate-limiting step in production. This emphasizes the concern about the current imbalance of omega-6 to omega-3 in our diets and its possible deleterious health consequences.

How should our society correct the balance?

Changing our diet is certainly the primary goal. Certain foods are a better source of omega-3 fatty acids than others. The reason is based on the type of omega-3 fatty acid present within it.

Bypassing the first assembly line is another way around this problem.

Flaxseed, although a great source of omega-3 fatty acids, contains the greatest concentration of ALA and must compete with linoleic acid to be processed.

Consuming seafood (shrimp, canned light tuna, salmon, pollock, and catfish) and fish oil is a good source of EPA and DHA and bypasses the enzyme needed to convert ALA to EPA and DHA.

This avoids the competition for the first assembly line stage.

Before we accept the health benefit claims from the makers of omega fatty acid supplements, more research into omega fatty acids is required. Besides, eating foods rich in omega-3′s provides a greater array of nutrients than any supplement can.

Later, we will cover the omega-3 dietary recommendations, the food quantities required to meet them and cover the most common and well-researched treatment uses.

.

Related articles:

1. Omega-3 fatty acids do not improve heart health when the barn door has already closed
2. Consuming the nutrients you need
3. The fat that keeps on giving

Originally Published in The Medical Post, May 11, 2004 Volume 40 Issue 19

As more adolescents adopt a meat-free diet, solid planning can ensure they meet energy and nutrient needs

Increasing numbers of adolescents, especially girls, are adopting vegetarian diets. Their reasons for choosing a vegetarian diet vary from animal welfare, health benefits and food safety to environmental and sociopolitical concerns. Surveys suggest that approximately 8% of adolescents in the United Kingdom and 6% of older elementary and high-school students in the midwestern United States consume a vegetarian diet.

Although vegetarian diets differ, the underlying principle remains the same. The human body needs adequate calories from fat and carbohydrates, specific nutrients and proteins. This can be accomplished with solid dietary planning but many youngsters do not follow an appropriate regimen. The “all things green” philosophy, although well-intentioned, does not provide a rational basis for proper nutrition.

Vegetarian lifestyle practices usually include exercise, reduced consumption of alcohol and avoidance of cigarettes, among other health-conscious decisions. Indeed, the vegetarian lifestyle is associated with a lower incidence of type 2 diabetes, obesity and heart disease.

Rapid growth cycles in childhood and adolescence consume nutrients at a rapid rate. Well-planned vegetarian diets can provide children with all the necessary nutrients that play a role in their growth and development.

The foods and supplements required depend on the degree of vegetarianism. There are five vegetarian categories:

• Semi-vegetarian: Meat is included in the diet occasionally. Some may consume chicken and/or fish but not red meat.

• Lacto-ovo vegetarian: Avoidance of meat, but eggs and milk are included.

• Lacto vegetarian: Dairy products are included, but eggs and meat are excluded.

• Vegan: All animal products, including eggs and dairy products are excluded from the diet.

It is not necessarily the type of vegetarian diet per se but the quality, variety and amount of food consumed that is relevant.

• Macrobiotic: Whole grains, especially brown rice, are emphasized and vegetables, fruit, legumes and seaweeds are included in the diet. Animal foods are limited to white meat, or white-meat fish may be included in the diet once or twice a week.

Vegetarian adolescents should eat a diet low in saturated fat and cholesterol and high in fibre, complex carbohydrates (such as beans and vegetables) and antioxidants.

High-fibre vegetarian diets tend to include less calorie-dense foods. This may create a sense of stomach fullness before enough energy is consumed. This is problematic for adolescents because of the great energy requirements during pubertal development.

Adolescents should eat frequent meals and snacks that include energy-dense foods such as whole-grain breads, enriched cereals, nuts, peanut, almond and cashew butters, tahini, cooked legumes, soybeans, sesame and sunflower seeds, avocados and dried fruits.

Food selection must be built around the consumption of essential amino acids. Animal-source proteins contain all the essential amino acids, but plant-based foods, except for soy, do not. Adding soybean products, complementary plants (such as brown rice to legumes or nut butters to bread), dairy or eggs will compensate for this lack. It is not necessary to consume all essential amino acids during the same meal, but they should be included over the course of a day.

Rapidly growing adolescents, especially menstruating females, require iron. Fifteen to 35% of the iron within meat (heme iron) is absorbed by the intestine, compared to 2% to 20% from plant sources (non-heme iron).

Certain chemical compounds within foods will bind with non-heme iron and prevent its absorption: tannins and polyphenols in tea and coffee form iron-tannate complexes that greatly reduce non-heme iron absorption. Phytates found in legumes, nuts, seeds, grains and soy will form insoluble non-heme complexes and reduce iron absorption.

Parents can encourage their adolescent child to choose from iron-fortified cereal, whole-grain or enriched bread, pasta or grains, legumes, dried fruit, green leafy vegetables, soy products, blackstrap molasses, bulgur and wheat germ. Milk and eggs are not good sources of iron.

Vitamin C will improve non-heme iron absorption. It must be consumed with the meal because of its mechanism of action. It will prevent the formation of less soluble ferric compounds, promote non-heme iron absorption and can counteract the inhibitory effect of phytates. A 75 mg dose of ascorbic acid increases the absorption of non-heme iron by three- to four-fold.

The addition of fruits and vegetables like citrus fruit, strawberries, broccoli and tomatoes can increase the absorption by three- to four-fold. Teens should be encouraged to consume vitamin C with every meal.

Zinc deficiency can lead to growth impairment, infections, diarrhea and pneumonia. Plant sources include whole grains, cereals, legumes, wheat germ and nuts. It is also found in dairy products, shellfish and meat.

Seventy-five per cent of the calcium requirements for children and adolescents come from the consumption of cow’s milk and dairy products. In the absence of dairy, calcium-fortified foods such as soy milk, orange juice, breakfast bars, waffles, pastas and cereals can help teens meet daily requirements. Calcium-rich foods do help, but large quantities would be needed. These include kale, turnips, mustard greens, broccoli, bok choy, dried figs, blackstrap molasses and lime-processed tortillas.

Calcium supplements can be used, but food sources are better because they include extra nutrients. Vegetarian children who do not drink cow’s milk should receive at least one calcium-rich or fortified food with each meal and snack. The daily calcium requirement for adolescents is about 1,000 to 1,500 mg per day.

Our bones attain peak bone mineral density by our mid-20s. Thereafter, bone mineral density will slowly decline. It is imperative that adolescents maximize their peak bone mineral density as a means of minimizing the debilitating effects of osteoporosis in later life. The principal dietary source of vitamin D for most people is fortified milk. Those who do not consume fortified cow’s milk, soy milk or breakfast cereal are at risk for deficiency that can lead to osteomalacia in adults.

Sun exposure and a dietary intake of 200 to 400 IU will maintain a healthy bone architecture. During the winter months, many can benefit from vitamin D supplements and enriched foods.

Meat, shellfish, eggs and dairy products provide virtually the only dietary source of vitamin B12. Without supplementation, many vegetarians, with the possible exception of semi-vegetarians, will suffer from vitamin B12 deficiency. This can cause anemia and nervous system dysfunction. Indeed, it is becoming all too common to uncover macrocytic anemias on younger people due primarily to dietary deficiencies.

Fortified meat substitutes, soy beverages, nutritional yeasts and cereals are good vegetarian sources of B12. Adolescents require about 6 mcg to 9 mcg daily.

The risk of nutritional deficiencies increases with the more restrictions within the diet. With proper planning, vegetarian diets are healthful. Dieticians are a valuable resource and should be involved with the adolescent patient’s dietary planning.

Related articles:

1. Infant nutrition
2. More vitals on vitamins
3. Battling B12 deficiency

Originally published in The Ottawa Citizen April 13, 2004

Original Title: Vitamin B12 deficiency

A change in your diet may not be enough to boost vitamin levels

In medicine, there is an old adage that the most common medical complaints are caused by the most common medical problems. Many of my patients have complained about fatigue. This nebulous creature is one of the most common problems faced by family doctors.

The usual suspects are low iron states, anemia, low thyroid hormone, diabetes, depression, infections, poor nutrition or diet and sleep disorders. Granted there are a myriad of other conditions that can cause this problem. However, more than 90 per cent of the time, the old adage rings true; the diagnosis will be one of the above.

Blood tests for the above disorders would follow after a medical history and physical exam.

Interestingly, I have seen a run of vitamin B12 deficiency lately in men and women of all age groups. The chief complaints are fatigue, lack of energy and motivation to complete tasks, vertigo, depression and confusion.

Vitamin B12 (cyanocobalamin) is required to produce red blood cells and maintain proper nervous system function.

B12 is found only in meat and dairy products. Even with the recommended intake of six to nine micrograms per day, several processes within the digestive system must be working in order for proper B12 absorption to occur.

Stomach acid will free B12 that is attached to the proteins in food. This liberated B12 will bind to intrinsic factor, a carrier molecule secreted by specific stomach cells. This B12-intrinsic factor complex will bind only in one region of the small intestine: the terminal ileum or far end of the small intestine. The pancreas will also secrete an enzyme that prevents B12 from binding to other protein complexes.

Let’s look at some of the mechanisms that will disrupt B12 absorption and, with time, lead to a deficiency state.

Long-term use of acid suppressing medication used to treat stomach ulcers, reflux disease and increased acid states (Zantac, Pepcid, Axid, Losec, Pariat, Prevacid, Pantaloc and Nexium) will reduce the amount of free B12 available to bind with intrinsic factor.

About 10 to 30 per cent of Type 2 diabetics using metformin will have problems absorbing B12. Calcium supplements will reverse this medication effect.

Some people’s immune systems can attack and destroy the stomach cells that produce intrinsic factor or the B12-intrinsic factor binding sites in the terminal ileum. This condition is called pernicious anemia. These people lose the ability to absorb B12 at the terminal ileum for life.

Stomach and bowel surgery, severe pancreatic disease and inflammatory bowel diseases such as Crohn’s or ulcerative colitis can impair absorption of B12.

Inadequate dietary B12 intake is commonly seen in vegetarians who avoid all animal and dairy products. Pregnant and lactating women require increased amounts of B12. If they follow a moderate vegetarian diet, they and their infants may become B12 deficient. The vitamin B12 levels in a fetus are twice as high as maternal blood levels.

The clinical complications of vitamin B12 deficiency will vary. Many people will develop macrocytic (large red blood cell) anemia.

When the nervous system is initially affected, people will report a loss of the ability to feel vibrations on their skin or their ability to sense their body position. In the latter condition, they can trip or lose their balance. The condition can progress to spastic or seizure-like attacks, paralysis and fecal and urinary incontinence.

Other nervous system impairments include memory loss, dementia and irritability.

Vitamin B12 is needed to assist in the breakdown of the amino acid homocysteine. Elevated levels of homocysteine are a risk factor for coronary artery disease and blood clots.

The treatment used to be centred on the assumption that people with malabsorption conditions like pernicious anemia required monthly injections of B12. Indeed, there is evidence that shows daily high dose oral replacement of 1,000 to 2,000 micrograms is as good as injection. There seems to be another intestinal area that absorbs B12 if the dose is great enough.

The choice of injection versus oral therapy will depend upon the underlying condition and should be discussed with your doctor

© Dr. Barry Dworkin 2004

Related articles:

1. More vitals on vitamins
2. Infant nutrition
3. Vitamin D deficiency and effect on cancer risk

Originally published in The Ottawa Citizen March 30, 2004

Original Title: The diet of the ages

It seems that every week there is another diet or celebrity offering the Holy Grail of diet and health nirvana. Indeed, nutritional science researchers are casting healthy skepticism on their claims.

The pace of health information and reporting can overwhelm and confuse people who are trying their best to select a proper diet lifestyle.

So, based on the latest evidence, what is the state of our understanding about diet and disease prevention?

Cardiovascular disease and stroke are the leading causes of death in our society. The lifetime risk of dying from cardiovascular disease is one in two for women and one in three for men.

The growing body of evidence suggests that the more raw fruit and vegetables consumed, the less the risk of stroke and heart disease. Studies indicate that people following diets that include five to six servings of cruciferous vegetables such as broccoli, cauliflower, cabbage and brussels sprouts, citrus fruits, green leafy vegetables and vitamin

C-rich fruits and vegetables have the lowest risk of stroke and heart disease. More than six servings per day did not confer any additional risk reduction.

Some of the proposed explanations for these findings are that these foods contain above average amounts of folic acid, potassium, antioxidants and fibre. All of these nutrients seem to offer protection against heart disease and stroke.

High-fibre diets can lower insulin levels, reducing the risk of heart disease and stroke. Cereal fibre has the strongest association with reduced risk. Studies indicate a 40- to 50-per-cent risk reduction for heart attack in high-fibre eaters (greater than eight grams per day) compared to those with a low intake (less than 3.2 grams per day). This has been borne out by the Framingham Heart Study and other research.

It is the soluble fibre found in fruits, vegetables and legumes that will improve the control of sugar levels in diabetics. It can help reduce the risk of obesity. A previous column (http://members.rogers.com/barrydworkin/sugars_not_equal.html) explains why diets rife with high glycemic index (GI) foods can increase the risk of type 2 diabetes. Indeed, the Canadian Diabetes Association dietary plans are based on the consumption of low-GI foods.

Although there is a negative connotation to fat consumption, it is the type of fat consumed, rather than the amount, that is significant. Hydrogenated fats (trans fatty acids) and saturated fats (animal products) increase the risk of coronary heart disease, whereas polyunsaturated fat (e.g. canola and corn oil) and monounsaturated fats (olive oil) lower the risk by decreasing cholesterol levels.

Although there is evidence correlating moderate alcohol consumption with a reduced risk of heart disease, especially among older men and women, a safe maximum has yet to be determined. The confounding factor is that alcohol is associated with an increased risk of breast, colon and liver cancers.

Eating should be an enjoyable experience, not a chore or laden with guilt. The consensus and recommendation for a healthful diet and heart health favours fresh foods over prepackaged and prepared foods.

Try to make fruits and vegetables part of every meal. Eat five to six servings a day (canned and frozen are acceptable alternatives). Choose different colours as each has different nutrients. Add fruit to your cereal and eat vegetables as snacks. Leave a bowl of fruit out for the children to snack on.

Make cereal fibre a dietary staple. Eat folate-rich foods such as fortified high-fibre cereals, oranges, orange juice and green leafy vegetables.

Avoid trans fatty acids (hydrogenated fats) and saturated fat. Choose chicken, fish or beans instead of red meat and cheese. Many store-made baked goods such as crackers, cookies and cakes contain hydrogenated fats. Margarine users should choose Becel because it does not have hydrogenated oils. Use canola and olive oils for cooking.

The evidence suggests that by sticking to low glycemic index foods, reducing your intake of alcohol, saturated fat and processed foods, and increasing your soluble fibre intake, you will have a healthier life. This does not impose insurmountable restrictions, is moderate in scope and is less difficult to implement than a wholesale change in eating habits and food selection as seen in some of the more popular diets. Moreover, it is sustainable and has a better chance of reducing weight and keeping it off.

Diabetics should consult their dietitian or physician before changing their diet to ensure that they will have proper blood sugar control.

© Dr. Barry Dworkin 2004

Related articles:

1. Sugars are not created equal
2. More vitals on vitamins
3. Helping vegetarian teens thrive

Originally published in The Ottawa Citizen December 16, 2003
Original Title: The vitals on vitamins – Part 2

Part 1 – Vitals on Vitamins

What do some of the B vitamins and antioxidants do? Are we dealing with marketing hype?

Vitamin B₆ (pyridoxine), found in whole grains, dried beans, eggs and nuts, is involved in the normal functioning of the central nervous system and in the production of red blood cells. It works in conjunction with folate and B₁₂ to reduce homocysteine levels.

Vitamin B₂ (riboflavin) and B₃ (niacin) aid in the release of energy from foods and each interacts with other B vitamins. Nuts, dairy products, fortified cereal and liver are good sources. Niacin helps in the synthesis of DNA and maintains normal functioning of the skin, nerves and digestive system.

Vitamin B₁₂ (cyanocobalamin) is found in liver, beef, eggs, milk and shellfish. Vitamin B₁₂ deficiency is commonly seen in patients with poor diets, vegans, alcoholics and people with various intestinal diseases. Unlike many other foods and minerals, a special substance called intrinsic factor aids in B₁₂‘s absorption in a specific area of the small intestine called the terminal ileum. The elderly tend to produce less intrinsic factor. Surgical resection of the terminal ileum will impair B₁₂ absorption.

B₁₂ deficiency will cause nervous system damage and megaloblastic anemia. It is the only water-soluble vitamin that is stored in the body. The liver has the potential to store about five years worth.

A number of studies looked at the potential of antioxidant vitamins, A, C, E and betacarotene in the prevention of cancer and heart disease. Antioxidants neutralize electrically charged chemical compounds called free radicals. Free radicals, like ozone and cigarette smoke byproducts, destroy normal tissue through a process called oxidation. It is the same process that causes rust.

Citrus fruits, strawberries and tomatoes are a good source of vitamin C (ascorbic acid). This vitamin helps maintain the growth and integrity of connective tissue throughout the body. It promotes healthy blood vessels, gums and teeth and aids in wound healing. Several long-term studies looking into cancer, stroke and heart disease prevention with vitamin C are inconclusive.

Observational studies tend to show that diets high in vegetables and fruits (that are rich in antioxidant vitamins) are associated with a reduced risk of cancer and cardiovascular disease. However, this effect may be due to the antioxidants, some other compound in the fruits or vegetables such as flavonoids or meat and fat reductions within the diet. A person’s genetic potential for cancer or conversely his/her response to antioxidant vitamins is also a consideration.

Vitamin A promotes good vision and maintains healthy skin and mucous membranes. Retinol is the active form of vitamin A (preformed vitamin A). It is found in animal products and supplements.

Beta-carotene is found in fruits (cantaloupe and apricots) and in vegetables (carrots and tomatoes). The body will convert it into retinol.

Cancer, stroke and heart disease prevention studies using vitamin A failed to demonstrate any benefit. Indeed in some lung and prostate cancer studies, the rate of cancer incidence increased. Beta-carotene supplement use should be discouraged because of its potential side effects and lack of clinical effect.

Studies noted that Vitamin A did improve the immunity status of children living in developing countries. The World Health Organization recommends supplementation at the community level because of the supporting evidence.

Women should avoid supplements with greater than 5000 units of vitamin and high dietary intake of preformed vitamin A found in foods such as liver, milk, egg yolk, and butter because of a possible increased risk of hip fractures in women especially those with low bone calcium content (osteopenia).

A notable exception is vitamin A in pregnancy which can cause birth defects at doses as low as several times the recommended daily allowance.

Vitamin E (alpha-tocopherol) is found in nuts, vegetable oils, whole grains, olives, asparagus and spinach. It helps in the production of red blood cells and helps the body use vitamin K. Vitamin K aids in blood clotting.

Although there is some evidence to support vitamin E’s ability to prevent aggressive prostate and lung cancer in smokers, it is not conclusive. Nearly all randomized trials have shown no benefit preventing coronary heart disease and stroke. Other studies indicate it does not improve immune system function.

Studies are ongoing to look at vitamin E’s effect upon the development of dementia and Alzheimer’s disease. Early data is encouraging but not enough to make any general recommendations.

The benefits of vitamin supplements remain a question mark. There is little evidence to support vitamin megadosing. Indeed, there are potential adverse interactions with prescription medication like anti-coagulants.

It is our diet rather than the vitamin supplements that has the greater impact on health. A diet with five or more servings of different colour vegetables, legumes and fruits per day will provide a wide range of vitamins, fibre and trace nutrients and will replace some meat and animal fat. It is and always has been about balance and moderation.

© Dr. Barry Dworkin 2003

Related articles:

1. The vitals on vitamins
2. Parents should be aware that certain vitamins may interact with other medications
3. The New Coke! Now with added vitamins and minerals

Originally published in The Ottawa Citizen December 9, 2003
Original Title: The vitals on vitamins

Part 2 – More vitals on vitamins

What are vitamins? Do they provide extra energy or boost to your metabolism? Do they help prevent cancer and other chronic diseases? How much is too much? A multibillion-dollar industry relies on the public perception that they are a gateway to better health and disease prevention. This two-part series will look at the facts and myths about vitamins based on the latest research.

Vitamins are a group of unrelated organic chemical compounds essential for normal metabolism. The true definition of vitamins does not include other food supplements, herbal products and minerals. With the exception of vitamin D, the body cannot synthesize these compounds.

Imagine within the body there are small factories. The raw material available to the factory comes from the food we eat. Each factory is tailored with the precise machinery (biochemical processes) necessary to covert the food into specialized products necessary for the body’s survival.

Vitamins integrate and co-operate with the body’s enzymes systems like a gear or cog in a machine does. They are co-enzymes.

Taking vitamin supplements will have less of a benefit if the diet is poor. They do not provide energy in the direct sense: consuming large quantities does not boost your energy level. Vitamins are essentially calorie-free. A factory ready to run peak efficiency will not be productive if there is a lack of raw material. Let us look at the factory components.

The B and C vitamins are water-soluble. Vitamins A, D and E are fat-soluble. With the exception of vitamin B12, the water-soluble vitamins are not stored for future use. Indeed, intake in excess of the body’s daily requirements (megadosing) creates expensive urine.

In Western countries, vitamin deficiencies appear in specific populations such as the elderly, alcoholics, people with intestinal malabsorption syndromes, genetic errors in biochemical metabolism, kidney dialysis patients and those people receiving nutrition solely through intravenous access. The physiological demands of pregnancy will require vitamin supplementation through dietary change or tablets.

The desire to prevent diseases due to nutritional deficiencies spawned the development of recommended daily allowances of vitamins. However, the recommendations may not be enough to prevent disease in some people. A newer concept regarding the adequacy of vitamin intake is the optimal daily ingestion of vitamins needed to prevent chronic disease like vitamin D supplementation to prevent osteoporotic fractures or folic acid to prevent neural tube defects.

The evidence to date indicates stronger support for folic acid, vitamin B₆, B₁₂ and D in the prevention of chronic disease than the antioxidant vitamins C, E and beta-carotene. Let us look at each of these in turn.

Folate (folic acid in supplements) is present in grains, nuts, beans, green leafy vegetables, liver, wheat bran and meats. Folate is required for normal cell division and growth. Folate deficiency leads to a blood disorder called megaloblastic anemia. The red blood cells become abnormally large and dysfunctional. Their oxygen carrying capacity is reduced causing fatigue.

Folate-poor diets prior to conception and through pregnancy can lead to neural tube defects. The neural tube forms a major component of the future central nervous system. Numerous studies demonstrate folate supplementation reduces the incidence of neural tube defects.

There is preliminary evidence that folate combined with vitamin B12 can reduce the risk of heart disease in certain individuals who have high blood levels of homocysteine. Homocysteine, a metabolic byproduct of protein metabolism, is associated with an increased risk coronary artery blockage and heart disease.

Several long-term folate supplement studies, the Nurses’ Health Study and the Health Professionals Study, indicate a 35 per cent lower risk of developing colon cancer for men and women after 15 years of folate use.

Vitamin D (cholecalciferol) deficiency in the elderly increases the risk of osteoporosis. Reduced sunlight exposure in winter and remaining housebound in addition to a poor diet increase this risk.

A study of men and women over 65 taking a normal daily dose (700 IU) of vitamin D with 500 milligrams of calcium resulted in reduced bone loss in several areas. It decreased the incidence of non-vertebral (spinal) fractures by one-half after three years.

Daily dosing of vitamin D must be combined with calcium to produce a positive effect on bone. One study showed a 100,000 IU oral megadose of vitamin D every 4 months for five years reduced the fracture risk of people 65 to 85 years of age without any toxic effects.

Next week we will look at the B vitamins and antioxidants vitamins A, C, E and beta-carotene. Where’s that bag of baby carrots?

© Dr. Barry Dworkin 2003

Related articles:

1. More vitals on vitamins
2. The New Coke! Now with added vitamins and minerals
3. Parents should be aware that certain vitamins may interact with other medications

Originally published in The Ottawa Citizen November 4, 2003
Original Title: A guilt free review of dining at your favourite eatery

A growing number of people are adopting a low-carbohydrate lifestyle. Indeed, a few studies support the Atkins diet, in the short-term, as a safe way to lose weight (the diet is contraindicated for some medical conditions). The Atkins diet can be difficult to follow over the long-term. Atkins recommends vitamin supplements but many forget to take them leading to an increased risk of vitamin deficiencies.

How does the diet work? One hypothesis is the quantity and quality of carbohydrate intake will affect insulin levels. Insulin enables the transfer of glucose (sugar) into cells and promotes fat storage. When eating a high-fat high-carbohydrate meal, insulin levels will spike in response to the high sugar load. Consequently, most of the fat within the meal will be stored in the fat cells whilst the body preferentially uses the easily metabolized sugar as its energy source.

The choice of dietary lifestyle should not be a chore (the death knell of any diet) but integrate itself seamlessly into daily life. What is the rationale for food combinations?

The proposed system promotes three food categories. Category A includes red meat, fish, chicken, fatty and processed meats, cheeses, oils and other fats. Category B includes fruits, vegetables, legumes and beans, and category C, pasta, potatoes, rice and bread.

The goal is to reduce insulin secretion after a meal. Combining A + B minimizes the sugar load and hence no insulin increase. The body uses fat as its energy source of choice. B +C limits fat intake and storage. A + C, the meat and potatoes diet, is assumed to be partially responsible for weight gain.

How would these categories help select dishes from a restaurant menu? The following exercise outlines an approach to menu selection and is intended for illustration purposes only. This is not a critique of the menus or an endorsement of any establishment over another.

Wendy’s fare offers hamburgers, chicken sandwiches, fries, chili and salads. A review of their nutrition/ingredient guide available for the asking can help you select an A+B meal. You can choose a hamburger with mustard, pickles, lettuce tomatoes and onions or their grilled (not breaded) chicken fillet with some side condiments without the bun. Add a side salad with either low fat honey mustard or fat-free French Style dressing, water or a diet soda and you now have a meal.

East Side Mario’s offers a broad range of appetizers, entrees and desserts. Fried mozzarella aside, there are several appetizers to choose from: the Sizzling Calamari Al Diavolo (sautéed in white wine, garlic, lemon, red, green and hot cherry peppers), steamed mussels, Baked Garlic Shrimp or Chicken Garden Salad (no croutons).

Many of their entrees come with unlimited soup or garden salad and garlic bread. Push the garlic bread away from the table and stick to the salad. Choose pasta dishes that do not have meat, cream sauces or cheese. Any pasta with Arrabbiatta or Napolitana sauce with primavera vegetables fits the bill. Meat lovers can choose from Hell’s Kitchen Chicken, Rack of Ribs or New York Steak all without fries, potatoes or pasta. Dessert: fuggedaboudit

The Kam Fung Chinese buffet is popular. The 30 or so items offer many choices and combinations. The dishes to avoid include any breaded meats, noodle dishes, spring and egg rolls and won ton soup. This still leaves a variety of tasty dishes: Hot and sour soup, beef or chicken with broccoli, beef with green pepper and onion, beef, shredded pork or chicken with garlic sauce, beef or shrimp with mixed vegetables, Kung Pao chicken and the salad and fruit bar.

For non-diabetics who wish to have noodles and plain white rice with their meal, select the meatless vegetable dishes.

All these selections lead to a net reduction in caloric intake. This in itself is a likely reason for weight loss. Marie Hebert, a dietitian with the Diabetes Clinic of the Ottawa Hospital has some concerns with this choice of diet. Indeed, she states this type of diet “may lead to an overconsumption of protein and a restriction in food choices and may have long term negative impact on health.” She asks where milk fits into this system.

One should not eliminate grains and other complex carbohydrates that form part of a healthy diet. Indeed, the glycemic index (http://diabetes.about.com/library/mendosagi/nmendosagi.htm) is a useful measure to select healthful carbohydrates.

There are indeed other factors to consider when choosing a weight reduction method: saturated and hydrogenated fats, protein load, quality and quantity of food, exercise and eating habits.

Hurrying through any meal does not allow the natural feedback mechanism of the body to signal satiety leading to overeating. It is imperative to combine diet and exercise. A dietician can help you select the proper meal plans and provide professional lifestyle advice based on your food preferences.

© Dr. Barry Dworkin 2003

Related articles:

1. How a low-carb, high-protein diet affects your body
2. Sugars are not created equal
3. For a healthier diet, just skip the latest fad

Originally published in The Ottawa Citizen August 12, 2003
Original Title: Low iron infant formulas

Dumb and dumber.

That’s what Dr. David Mack, chief of pediatric gastroenterology at the Children’s Hospital of Eastern Ontario, thinks about low-iron infant formulas.

“On the one hand,” he says, “formula companies are adding nutrients found in breast milk to promote the development of cognitive and visual development. Yet the lack of iron has the potential to thwart this development.”

The recent addition of two essential fatty acids, decosahexanoic acid (DHA) and arachidonic acid (ARA) into some formulas is a case in point. These fatty acids promote visual acuity and cognitive development in preterm and term infants and may be involved in other critical body functions.

It is ironic, Dr. Mack says, that these same companies would offer reduced-iron formulas. In a letter to Dr. Margaret Boland, chair of the nutrition committee of the Canadian Pediatric Society, Dr. Mack shares his concerns about this trend.

Pharmacies and grocery stores provide similar shelf space for low-iron cow milk-based formulas, he observes. Parents often do not notice that the product is low in iron content. There is also the perception that both types of formula provide equal benefit.

Parents will often change formulas either on their own accord or on the advice of their health care provider if their formula-fed child becomes more fussy, has cramping, colic, acid reflux from the stomach, flatulence or increased spitting-up. But there is no evidence that links formula-iron content with these conditions.

Dr. Mack notes that one of the first tendencies is to switch in error to a low-iron formula if there is a suspicion of an intolerance to cow-milk protein.

Within his practice, he often encounters the urban myth of iron causing infant constipation. However, this is actually rare. The infrequent bowel movements of soft stools result from inadequate intake of formula.

Switching to a low-iron formula further compounds the problem. The infant suffers an increased risk of iron deficiency anemia. This anemia, or reduction of oxygen transporting red blood cells, reduces the delivery of oxygen to the developing infant, especially the brain and nervous system. Iron-deficiency anemia is associated with problems in cognitive, behavioural and physical development in infants and children.

Some parents continue with low-iron-based formulas because hospitals stock and distribute them to parents for newborn feeds.

There are a few reasons why low-iron formula use is so common. Similar product packaging, poor labelling, a general lack of knowledge regarding the importance of iron in infancy and a lack of physician and nurse intervention are some of the reasons parents continue to use these products.

But there is no scientific evidence to support this product class.

There are no known medical contraindications to using iron-fortified formulas. Professional organizations do not advocate using low-iron formulas. Even the formula company representatives discourage its use.

“Public health policy successes include the introduction of iron-fortified infant formulas in the 1970s with the prevalence of iron-deficiency anemia being dramatically reduced,” Dr. Mack notes. However, Canadian infants and children are still at risk.

So why does this product remain on the store shelves? Dr. Mack believes sales of low-iron formula must still be significant enough to continue the product line.

With the exception of cow-based formulas, all other formula groups (i.e. soy-based, hydrolysate, amino acid) are iron-fortified.

Dr. Mack has six recommendations for the use and content of cow milk-based formulas. He asks the Nutrition Committee of the Canadian Society for Pediatrics to adopt and recommend these principles.

1. Infants who are not breast-fed or partially breast-fed should receive an iron-fortified formula.

2. Discontinue the manufacture of low-iron infant formula.

3. If low-iron infant formula continues to be available to consumers, the label must contain a health warning about the risk of iron deficiency anemia and its effects upon infant growth and development.

There must be consistent labelling practices akin to other formula groups (i.e. soy, hydrolyzed and amino acid). Manufacturers should remove the term ‘with iron’ from the front label. All listings including iron content should appear on the package nutrient content label.

4. The Hospital Association recommend to their members not to supply low-iron infant formula in their hospitals.

5. The distributors of low-iron infant formula should not provide shelf-space for low- iron infant formulas. A physician note would be required to obtain low-iron infant formula.

6. The Canadian Pediatric Society and formula manufacturers continue to provide education for the public and for health care providers regarding iron and infant growth and development.

If no one buys the product, companies will not sell it. It’s one way consumers can influence health outcomes and corporate behaviour.

Related articles:

1. Infant nutrition
2. Iron Overload
3. Consuming the nutrients you need

Originally published in The Ottawa Citizen March 4, 2003
Original Title: Sugar by the numbers

Last week’s column reviewed how what we eat can influence blood insulin levels. Diets high in carbohydrates (sugar) result in elevated insulin levels or hyperinsulinemia. This in turn may lead to obesity, insulin resistance and type 2 diabetes.

Diets like he popular Atkin’s diet restricts carbohydrate intake. Weight loss occurs because the body taps its fat stores to fulfill its daily energy requirements. Through biochemical processes, fats convert into glucose (sugar). Glucose is the main fuel that provides the energy for the body’s metabolism.

Carbohydrates are sugar molecules that come in two types: simple and complex. Sugars like glucose, fructose and others link together like a chain to form complex sugars.

Fruits, milk and milk products, vegetables and refined products such as candy, table sugar, syrups (not including natural syrups such as maple) and regular sodas contain simple sugars. Starchy vegetables, legumes, rice, pasta, cereals and bread contain complex sugars.

The body will absorb and convert simple and complex carbohydrates into glucose at different rates. Blood sugar levels depend upon this glucose production rate and the amount of sugar within the food.

A ranking system of these rates for over 750 carbohydrate-containing foods exists (available at http://diabetes.about.com/library/mendosagi/ngilists.htm ). This system uses two measurements, the glycemic index (GI) and the glycemic load (GL).

The glycemic index measures the speed that a carbohydrate (for three hours after a meal) is turned into glucose. A value of 55 or less is low, 56 to 69 is medium and 70 and above is high. These rates are set against glucose that has a value of 100.

Fibre is a carbohydrate that comes in two types. Fruits, vegetables and legumes contain soluble fibre that slows the rise in blood glucose after a meal. Whole-wheat bread and brown rice among other foods contain insoluble fibre. Insoluble fibre promotes regular bowel movements and has little effect upon blood sugar levels.

The glycemic load tells you how much carbohydrate (minus the fibre content because it does not contribute to glucose production) is available in a particular food. A glycemic load of ten grams or less per serving is low, 11 to 19 is average and 20 or greater is high.

Both the glycemic index and glycemic load are necessary to determine whether the food provides too great a sugar load.

Indeed many a healthful diet contains foods that are low in fat content yet may not be appropriate for diabetics and people on weight-reducing diets.

Scanning through the list reveals that rice and cereals have some of the greatest glycemic indices and loads. This data goes against the grain (pardon the pun) of our assumptions. A Russet potato has a greater glycemic index than table sugar. Pumpernickel has a glycemic load half that of white bread.

There are differences within food groups. A 250 millilitre serving of Allen’s(r) apple juice has a GI of 40 and a GL of 12 grams. Compare this to the same quantity of Ocean Spray(r) Cranberry Cocktail with a GI of 68 and GL of 24 grams. The body produces glucose from the cocktail’s carbohydrate 70 per cent faster than it does for the apple juice. The cocktail also has double the sugar content of the apple juice leading to more glucose production.

A 120-gram apple has a GI of 34 and a GL of 5 compared to 60 grams of raisins with a GI of 64 and GL of 28 grams.

A 30-gram serving of Kellogg’s Corn Flakes(tm) has a GI of 86 and GL of 22, Cheerios(tm) 74 and 15 and Kellogg’s All-Bran(tm) 51 and 9.

The list provides a means to choose foods with a low to average glycemic index and low glycemic load to minimize insulin spikes and potential weight gain over time.

There is another list of very low glycemic index foods known as free foods (http://www.mendosa.com/freefoods.htm). These foods, like celery or tomatoes, have little to no effect upon glucose and insulin levels. They are guilt-free foods.

Does this mean everyone should avoid or reduce their carbohydrate consumption to manage their weight? The indices are useful as a guide but should not be the sole measure of a healthful diet. Indeed, most diets should include lots of fruits and vegetables, high-fibre foods and foods low in saturated and hydrogenated fat. Diabetics must also be wary of excess protein in their diets. Regular exercise should be part of any weight loss or maintenance program.

Mars Bar lovers take note. It has a GI of 65 and GL of 26. Ice Cream aficionados seem to have the better treat: a GI from 38 to 61 and GL of 5 to 8. Bragging rights are short-lived once you account for all the extra fat. There is no free ticket. C’est la vie.

© Dr. Barry Dworkin 2003

Related articles:

1. How a low-carb, high-protein diet affects your body
2. For a healthier diet, just skip the latest fad
3. A low carb dining review of your favourite eatery