Originally published in The Ottawa Citizen December 9, 2003
Original Title: The 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?