Questionable Benefits Of Vitamins

Vitamins are nutritional substances that, when ingested in adequate, limited amounts, help the body perform its natural functions optimally. For example, vitamin D helps to maintain strong and healthy bones, and vitamins of the B complex help to produce certain vital proteins called enzymes.

The designation of vitamin is attributed to any substance that the body cannot synthesize in sufficient quantities to supply its needs. As a consequence, humans get most of their vitamins from the food they eat.

Everyone is familiar with vitamin C being widely present in oranges or kiwis, for instance. Nevertheless, multivitamin supplements are perhaps the most famous dietary supplements worldwide and the most commonly used in developed countries.

In a study conducted between 1999 and 2000 in the United States of America, 35 percent of adults reported recent use of multivitamin supplements. In 2010, the supplement industry reached a staggering $28 billion in sales in the United States alone, with similar trends having been observed in the UK and in other European countries. This number has continued to grow, and the vitamin industry is expected to reach global revenue of $71 billion by 2028.

Vitamins are important. But are the vitamin supplements important too?

People resort to using vitamin supplements with the goal of ensuring adequate intake, to preventing a disease, or to treat or complement the treatment of a disease. But are vitamin supplements really that great for the average consumer? Do they actually have a role in promoting health and preventing disease? Several scientifically sound studies have been conducted to analyze if the additional vitamin intake is beneficial under several circumstances.

A meta-analysis conducted in 2010 by researchers from several institutions, including the Johns Hopkins School of Medicine, looked at the results of 14 clinical trials that evaluated the relationship of folic acid (also known as vitamin B9) supplementation with cardiovascular events.

Analyzing the data collected from nearly 39 thousand individuals, this research group demonstrated that, although previous studies had suggested otherwise, ingesting additional amounts of folic acid has no effect whatsoever in cardiovascular disease, coronary heart disease or mortality prevention in general. In fact, when administered to patients with high baseline levels of a substance called homocysteine, folic acid supplements can even increase the risk for the listed conditions.

See Also: Vitamins or Not?

Another analysis looked at the famous vitamin D and how it correlated with the prevention of medical conditions like diabetes, colorectal cancer and cardiovascular disease. Appropriate intake of vitamin is essential to overall health, more specifically bone health, but a significant number of observational studies had suggested that higher levels of vitamin D could be helpful in prevention of multiple non-bone-related conditions. But when Professor Philippe Autier from International Prevention Research Institute in France looked at the overall results of 172 reported clinical trials, he found that people who were given supplemental doses of vitamin D had no significant reduction in the risk of developing any disease.

Multiple Research Suggest That Vitamin Supplementation Offers Only Limited Help In Various Medical Conditions

A more surprising, and recent, analysis by the US Preventive Services Task Force is now challenging the commonly accepted belief that increasing the intake of both vitamin D and calcium is a good preventive measure for bone fractures in older adults.

There is no question that both compounds are important for good bone health as they are essential for the formation of bone cells and also for a properly-functioning metabolism. But this study, which examined the conclusions of a number of clinical trials, demonstrates that, after all, we're still lacking the solid evidence that giving supplemental doses of vitamin D and calcium is beneficial for men and postmenopausal women.

Postmenopausal women are at a higher risk for osteoporosis and, as a consequence, for bone fractures. As a consequence, many commercial supplement products containing both vitamin D and calcium specifically target these women. The data available to this day is still insufficient to assume that the potential benefits of the intake of this combination of substances surpasses its potential harms.

As this study reminds us, in spite of the chance of this occurring being small, ingesting certain levels of vitamin D and calcium can result in the formation of renal (kindey) stones. All in all, more research is needed to assess the true value of combining vitamin D and calcium to prevent fractures. The data available so far point to the little, if any, effect of such supplement combinations.

Vitamins and dementia: Conflicting evidence

Several studies assessed yet another assumed effect of multivitamin supplements: the beneficial action in preventing normal cognitive decline associated with age. This group of researchers followed a group of almost six thousand people, aged 65 year or older, for a total of 12 years.

These findings match the results from another important review of 12 clinical trials that evaluated the effects of B vitamins, vitamins E and C and others in people with mild cognitive impairment or mild to moderate dementia. None of these supplements tested so far improved the cognitive function of older adults. The findings contradict a number of earlier reports that suggest that vitamin supplementation provides moderate benefits in reducing the risk of dementia. More research needs to be done to clarify this question, which means the answer is far from settled at the present moment.

See Also: Benefits Of Vitamin D Called Into Question

Many more studies, reviews and recommendations have been conducted on this somewhat controversial topic and they have consistently reached the same conclusion: not all vitamin supplements are helpful.

In special circumstances, such as in the face of a vitamin deficiency severe enough that it cannot easily be corrected through improved diet, vitamin supplements are extremely useful. In other situations, however, they are not. These substantial facts have, of course, an impact on public health and clinical practice. Therefore, more research is needed to establish the real influence of vitamin supplements on human health.

In the meantime, it is prudent for individuals to remember that, regardless of the potential benefits of multivitamins that may or may not exist, vitamin supplements can never, and must never, replace a healthy diet consiting of real foods.