Runner’s Plate: Do I Need a Vitamin or Mineral Supplement?
Posted Feb 21 2012 8:44am
I’ve recently had the opportunity to attend several sports nutrition lectures in the Boston area, and one of the things I’ve noticed is that regardless of the age or sport, one of the most common questions asked is “should I be taking a vitamin supplement?”
This is a difficult question to answer without knowing what an individuals diet looks like, but more often than not the answer will be no. Surprised? Here’s why:
Research shows that athletes and non-athletes have similar vitamin status. One exception is iron (see below).
There is no scientific evidence to support the claim that taking a multivatimin (or another vitamin supplement) or consuming greater amounts than the recommended dietary allowance (RDA) improves performance.
The more you exercise, the more you eat. If you are choosing vitamin rich foods the majority of the time (i.e. a variety of fruits, vegetables, whole grains, lean meats, and dairy), you should be getting adequate amounts of vitamins and minerals from food.
There are, of course some exceptions:
The largest exception is iron. Many athletes (particularly female endurance athletes) experience iron deficiency anemia. The key here though is the word deficiency. While I still recommend attempting to get vitamins from food, sometimes non red-meat eating athletes have low iron levels, particularly vegans and vegetarians. Non-heme iron (the iron found in plant sources like leafy green vegetables and beans), is less bioavailable (readily absorbed by our body) than heme iron (the kind found in red meat). A study among 18 female athletes helps illustrate this. Half of the women ate red meat, and the other half did not (though they ate chicken, fish, and eggs), but both groups were consuming 15mg/day (slightly under the RDA of 18mg/day for women 18-50). 8 of the 9 non-red meat-eating women were found to have depleted serum ferratin (iron) stores, whereas only 2 of the 9 red-meat eaters were depleted. That doesn’t mean if you don’t eat red meat, you can’t get enough iron from other foods – you just may need to eat a little more. Good sources of plant-based iron include: fortified breakfast cereal like Total or Wheaties, beans (soy, lentils, kidney, lima, navy, black, pinto, etc), tofu, and leafy green vegetables like kale and spinach. Also, watch what you eat with iron-rich foods (or when taking a supplement). Foods with vitamin C enhance the absorption (i.e. citrus fruit or juices), whereas calcium, tannins (found in teas and wine), some phytates (found in whole grains and legumes), and polyphenols can decrease absorption of non-heme iron.
One of the earliest and most obvious signs of iron-depletion or and iron deficiency is fatigue. If you are feeling more tired than usual and it’s not due to lack of sleep, low-calorie intake, or over exercising, you might want to have your iron levels checked by a doctor to see if a supplement is necessary.
Vitamin D. Athletes don’t necessarily need anymore vitamin D than non-athletes, but it’s a common vitamin for people to be deficient in. We get the majority of our vitamin D from the sun, so you’re more likely to have lower levels in the winter, particularly if you live in the northern part of the country. It’s also difficult to get through food, as the top sources are fortified milk and juice, and fatty fish like salmon. If you have darker skin and/or don’t spend much time outside (or are wearing sunscreen when you run), you may be deficient. Have your doctor test your levels at your next check-up (preferably in the winter months or early spring), it’s an easy thing to add to a standard blood test when checking cholesterol lipid levels.
In addition, if you are on a calorie-restricted diet and/or entire food groups are missing from your diet a supplement may be beneficial. Not because you require more vitamins, but because you may not be getting enough from food of you are restricting your calories.
There are other special scenarios in which a multivitamin supplement may be beneficial. If you are on a special diet because of allergies or food intolerances, check with your doctor or with a registered dietitian to see if you might need a supplement. Pregnant women should also talk to their doctors about vitamins.
Isn’t a multivitamin just a good insurance policy?
This is where you’ll find different opinions, even amongst dietitians. Research has not yet shown a clear benefit of taking multivitamins, and the bioavailability (amount your body absorbs) from supplements is, in most cases, less than it is from food and varies greatly from one individual to another. If you’re eating a varied diet full of fruits, vegetables, and whole grains, and some dairy (or other foods with calcium and vitamin D), you are more than likely getting what you need (and maybe more!). A lot of foods are fortified these days too, adding to your intake.
A multi-vitamin is unlikely to cause any harm, but it’s also probably not doing you much good. Side note: if you were alarmed by this recent study on multivitamins , don’t be. I won’t get into details, but there are a lot of reasons that you should not take this conclusion to heart (if you want to know more – feel free to ask me). Therefore, I’m in the camp that they are a waste of money because you’re probably excreting most of what you’re consuming in your urine. The same goes for individual vitamins and minerals. Again, if someone has a clear deficiency, that’s another story.
In full disclosure, I take a vitamin D supplement (my levels have been low in blood tests) and calcium because I am fairly certain I don’t consume enough through my diet.
Do you take a multivitamin? If you do, do you think you really need it?
(Sarah is a 2nd year grad student pursuing her MS in Nutrition Communication at Tufts University Friedman School in Boston. She is also completing the requirements to become a registered dietitian and will begin her dietetic internship in 2012. Sarah is a certified spin instructor and an avid runner and regularly participates in road races from 5k to a 1/2 marathons. Follow her on Twitter @SpinnerSarah and at her personal blog Food and Fitness Friend .)