Recently the local news reported on a study outcome suggesting multivitamins did not reduce the risk of cardiovascular disease. In fact, the National Institutes of Health and the US Preventive Task Force advise against the routine use of multivitamins in healthy individuals for the purpose of disease prevention. There is simply not enough evidence to recommend them across the board. However, they remain very popular! Have you ever wondered if you should take a daily multivitamin? Let’s break this down.
This recent analysis looked at 18 research studies from 1996 through 2016. Most of the studies analyzed looked at multivitamin use across “healthy” individuals, or those with no history of heart disease or cancer. Each study controlled for various confounding factors, including (but not limited to) age, sex, race/ethnicity, alcohol and tobacco use, and the presence of other chronic diseases (i.e. diabetes, hypertension). The studies were looking at incidence, or new diagnosis, of heart disease, stroke, and/or mortality (risk of death).
The analysis found no association between multivitamin supplement use and cardiovascular disease (plaque buildup on arteries), coronary heart disease (narrowing of arteries), or stroke mortality. So, taking these supplements is not associated with preventing death from these diseases. It did find a slightly reduced risk of coronary heart disease incidence in those who took multivitamins (again, meaning fewer new diagnoses of this condition). However, there were some limitations with this finding.
So, what does this mean for you? Should you take a supplement just in case? Or save your money?
This was one study, albeit a large one, looking primarily at cardiovascular disease risk. However, other supplement research remains contradictory. One study may show a slight benefit, while other may suggest risk with supplementation.
A limitation when it comes to studying supplements is the lack of uniformity in dose and formulation. The research studies used above used different types of supplements, which had variable amounts of each nutrient. There is no consistency. This is true in real life as well. As mentioned in previous posts, supplements are not regulated. In most cases you have no idea whether the supplement contains what it says it does. Consumer lab consistently finds products that do not live up to label claims.
Supplements carry risks.
Getting too much of a nutrient carries risk just like getting too little. This is called toxicity. Antioxidant supplements, for example, have actually been associated with an increased risk of certain cancers. More is not better.
That being said, supplements are sometimes necessary.
There are instances where supplements are important. Examples include deficiency states, such as iron deficiency anemia, or malabsorptive states including the period following bowel or weight loss surgeries. These conditions require routine monitoring by a medical professional. Lifelong vegans often require a vitamin B12 supplement, as this is a nutrient found primarily in meat and dairy products. Working with a registered dietitian can help you determine whether you should be taking a supplement. An assessment of dietary intake is necessary to determine your vitamin/mineral status, as blood work is often not reflective of nutrient intake. For example, blood calcium levels have nothing to do with how much milk you drink.
In a perfect world we would all eat a well-balanced diet full of fruits and vegetables. As a society, we continue to try to isolate nutrients, package them into a pill, and promote them as a cure-all. Unfortunately, in nature, nutrients are never found in an isolated state. When we take supplements, we miss out on synergistic effects of the nutrients working together, along with our bodies’ own ability to self-regulate absorption. For example, when our iron stores are low, our bodies increase their absorption capacity. When our stores are high, absorption decreases. There are compounds found in foods that also regulate how much of a nutrient is bioavailable, or available for absorption in the body. It is nearly impossible to over-consume vitamins from food sources!
Multivitamin supplements are unlikely to offer a meaningful benefit on disease prevention in otherwise healthy people. If you have a very restrictive diet, they may be helpful in meeting minimum nutrient needs. However, they cannot replace a well-balanced diet. That being said, if you want to take a supplement “just in case”, it is unlikely to cause harm. I would recommend getting one that meets no more than 100% of your daily value (listed on the supplement facts label) to reduce the chance for toxicity, and always tell your doctor if you are taking any over-the-counter vitamins, minerals, or supplements!