Technical Talk – Jan/Feb 2011

There are many factors that contribute to human and animal nutrition.
Vitamins play an integral role in making our bodies well-oiled machines.

Understanding vitamins and the role they play in good nutrition is the key to satisfying growing consumer demand for healthier whole foods

There are many factors that contribute to human and animal nutrition. Vitamins play an integral role in making our bodies well-oiled machines. Vitamins are a group of chemical compounds present in many foods of plant, animal or microbial origin, needed only in minute quantities for normal metabolic functioning. Vitamins are supplied through food or supplements. Our bodies also synthesize some nutrients by converting other compounds into vitamins, as is the case with vitamin D.

Vitamins are either fat or water soluble. Examples of fat soluble vitamins include vitamins A, D, E and K, which are normally absorbed by the body with the fats we eat. These vitamins are not normally excreted in our urine and can accumulate in our bodies. Most other vitamins are water soluble. Any excess amounts of water soluble vitamins tend to be peed out, with only minor amounts left behind. Accumulation may lead to issues with toxicity from certain vitamins, especially the fat soluble ones. However, toxicity cases are very rare and are usually the result of over consumption or excessive fortification.

Vitamins are a group of chemical compounds humans need in very small amounts to function normally.

Different vitamins have varying functions, depending on the role they play in our bodies. Common vitamins include A, B6, B12, D, E, K, thiamin, riboflavin, niacin, folate, biotin, and pantothenic acid. Vitamins arise in complex and numerous forms. For example, vitamin E occurs in alpha, beta, gamma and delta varieties of tocopherol and tocotrienol forms. Alpha and gamma tocopherols are the most common forms used in North America and Europe, either as supplements or for the enrichment of foods. Similarly, vitamin D occurs mainly as D2 ergocalciferol, which is obtained through diet, and D3 cholecalciferol, which is produced in the skin upon exposure to UV light. Vitamin D2 is commercially synthesized by the irradiation of plant sterols with UV light. Recent research has shown that the vitamin D2 content of mushrooms can be significantly elevated by exposing them to UV light. This is due to the conversion of the ergosterol found in fungi into ergolcalciferol, or vitamin D2. The baking industry has put this discovery to use in manufacturing yeast with high levels of vitamin D2. This represents a significant innovation that will allow for natural vitamin D2 fortification of bread and other yeast-raised baked goods.

Past consumer demand for refined foods resulted in the processing of various grains, which removed most of the vitamins and minerals normally found in the outer portions of the kernel. This had a detrimental effect on the modern human diet, and on nutrition. Recognizing these inadequacies, governments around the world introduced mandatory fortification of flour and other staples with specified vitamins and minerals. Today, modern consumers are aware of the nutritional value of whole foods and demand for unrefined grains is on the rise. Fortification practices vary between countries and regions. In Canada, enriched white flour and enriched white bread, respectively, have to be fortified with the following vitamin levels: thiamine (0.64 mg and 0.40 mg/100 g), riboflavin (0.40 mg and 0.24 mg/100 g), niacin or niacinamide (5.3 mg and 3.3 mg/100 g) and folic acid (0.15 mg and 0.10 mg/100 g). Vitamin B6 and d-pantothenic acid may also be added on a voluntary basis to fortify flour. Fortifying foods can ensure proper nutrition for the population and especially for children. This is particularly important for developing countries, but benefits have been observed in industrial countries. In 1997, Ontario introduced mandatory fortification of flour with folic acid. Since then, the incidence of neural tube defects such as spina bifida, which is believed to be caused by insufficient folic acid intake during pregnancy, has been reduced by more than 50 per cent.

Factors that limit the nutritional value of vitamins in our diets include losses during storage, processing, shelf life of the finished food product, and bioavailability (the extent to which a nutrient or medication can be used by the body). Bioavailability varies with the different forms of vitamins and the ability of the body to absorb them and utilize them. Some vitamins will oxidize quickly in a food system and their nutritional value will diminish substantially. For example, tetrahydrofolic acid, a naturally occurring derivative of folic acid, will oxidize and degrade very quickly, while the synthetic form of folic acid is very stable in food systems. For this reason, fortified food producers use the latter form to boost folic acid levels.

Some vitamins also play a functional role in food systems. For example, vitamin E is an effective natural antioxidant. Vitamin C, or ascorbic acid, is another powerful antioxidant and reducing agent used frequently in the food industry. Ascorbic acid will inhibit enzymatic browning in processed fruits and vegetables, provide protection for various products prone to oxidation, and prevent nitrosamine formation in cured meats. It is also an effective oxygen scavenger. In bread baking, ascorbic acid is used as a reducing agent in dough conditioners.

Different vitamins have different Recommended Daily Intake (RDI) levels in different countries. These levels are continuously modified as research provides new evidence on the health benefits and safety of various vitamins. Vitamin D has been extensively researched lately, and has been found to have several health benefits. Taking into account the abundance of evidence, the American non-profit Institute of Medicine recently proposed increasing the upper daily limits for vitamin D intake from 1,000 to 4,000 international units (IU). However, some experts consider even these levels too conservative.

In our efforts to develop food products that provide nutrition and health benefits to consumers, we may look at the vitamin content of our products. However, we should be aware of the regulatory and labelling issues pertaining to manufacturing and marketing such products. / BJ

Dr. John Michaelides is Guelph Food Technology Centre’s director of research and technology. For more information, or fee for service help with product or process development needs, please contact the GFTC at (519) 821-1246 or by e-mail at gftc@gftc.ca