"Now stay tuned for which vitamin may help you live longer" -- so teased an anchor at NBC's Chicago TV station one morning in mid-June of this year. Viewers were eventually rewarded with news on a study indicating that people (median age of 70) who took vitamin D in conjunction with calcium were less likely to die over a three-year period. The research, published in the Journal of Clinical Endocrinology & Metabolism, involved more than 70,000 people.
The news followed just days after the U.S. Preventive Services Task Force issued a draft statement (http://www.uspreventiveservicestaskforce.org/uspstf12/vitamind/vitdfact.pdf) advising healthy post-menopausal women against taking low doses of calcium and vitamin D supplements to reduce risk of bone fractures. For vitamin D3, this would typically be 400 IU or less per day and 1,000 mg or less of calcium. That recommendation itself is a reversal of years of advice given to aging women concerned about bone strength.
Such an about-face in nutritional science frustrates consumers and the medical community alike, but is also understandable. As the one-liner, known as Harvard's Law, says: "Under the most rigorously controlled conditions of pressure, temperature, volume, humidity, and other variables, the organism will do as it damn well pleases." Human biology and behavior are far from controllable, and each study faces myriads of difficult-to-account-for confounding factors. Ongoing research on vitamins will continue to create controversy over both the optimal amounts to consume as well as emerging health benefits. (See also Vitamin D Makes the Grade.
Despite the twists and turns in research, vitamins are generally seen in a positive light by consumers, a fact that food manufacturers use in product promotions. As just one example, Kraft Foods' new Capri Sun Super V Fruit & Vegetable Juice Drink draws in consumers with the front label claim "good source of antioxidant vitamins A, C & E." And, as food processors continue to develop innovative foods, many require a helping of vitamins to round out their nutritional profile.
"Nothing can replace the nutrition that a well rounded diet can provide. However, our lives seem to have us running 24/7, which doesn't leave a lot of time for consistent, nutritious meals," says Patrick Morris, communications manager for nutrient premix company Fortitech Inc. (www.fortitech.com), Schenectady, N.Y. "That being said, fortified products can help to fill the nutrient gaps caused by our hectic lifestyles. They can also help address the management of a variety of health issues."
According to Packaged Facts' 2012 "Dairy Alternative Beverages in the U.S." report, total retail sales of soymilk, almond milk, rice milk and other plant milks reached $1.3 billion in 2011. It also notes that 54 percent of Americans who purchase soymilk do so because of its nutritional characteristics. Vitamins are often an important element in these products' formula, prompting companies such as So Delicious to fortify its AlmondPlus beverages with folic acid and vitamins A, D2 and B12.
Indeed, in the International Food Information Council's 2012 Food & Health Survey, 47 percent of respondents indicate they are trying to "get a certain amount or as much as possible" of vitamins and minerals. Although interest in these traditional nutritional components fell lower than for whole grains, fiber and protein, it was greater than for calcium, omega-3s, potassium and probiotics.
The fundamentals of vitamin nutrition are reasonably well understood. In general, 13 vitamins are required by humans. Four are fat-soluble (A, D, E and K) and nine are water-soluble (vitamin C and eight B vitamins). Since the water-soluble vitamins are more quickly excreted by the body, fairly steady consumption is required. In contrast, fat-soluble vitamins tend to be stored in the body, so over-consumption is of concern.
U.S. regulations limit the amount of vitamin D3 used to fortify foods -- 140 IU per 240ml of soy protein-based meal replacement beverages and 100 IU per 240ml of fruit juices drinks with a minimum 10 percent real fruit juice (per CFR Title 21 Section 172.380, http://tinyurl.com/bqmr5h2).
The need for any particular vitamin varies by organism and sometimes by circumstances. Vitamin C (ascorbic acid) is needed in the diets of certain primates, including humans, guinea pigs and bats, but not by most other mammals. Thus, the vitamin C that may appear in ingredient legends of cat or dog food functions as a preservative (antioxidant) rather than as a nutrient.
Even in humans, the need for vitamin D and biotin (aka vitamin B7 or vitamin H) depends on circumstances. With enough exposure to ultraviolet light of the UVB type, human bodies synthesize their own vitamin D, which is a hormone-like compound. As for biotin, intestinal bacteria can usually produce a daily requirement's worth.
What excites most are studies linking vitamins to health conditions beyond deficiency. In the May issue of the American Journal of Clinical Nutrition, a meta-analysis study showed vitamin C to lower blood pressure. In the journal's January issue, vitamin B2 lowered blood pressure in people with a particular genetic factor, estimated to be about 10 percent of the population.
Such discoveries will help individuals to better craft vitamin consumption for their own specific needs.