Dr. Theresa DeLorenzo RD
Athletes, clients, friends, and family members often ask me what vitamins and minerals they should be taking. This is a complicated question. One would assume it is good to take a multivitamin to fill in dietary gaps. This may be true, but it can also be harmful if done incorrectly.
If you eat a varied diet with whole grains, plenty of calories, protein, fruits and vegetables, you probably do not need a multivitamin. But what’s the harm? To be honest, the risk of harm is real. With that said, some circumstances necessitate supplementation. Let me explain.
Most multivitamins contain exponentially more than 100% of the daily value of water-soluble vitamins. The assumption has been that water-soluble vitamins are not harmful in excess because we excrete what we don’t need, while fat-soluble vitamins, stored in fat cells, can be harmful if we get too much. Well, not exactly.
We now know that B and C vitamins, the water-soluble vitamins (supposedly the “not harmful” ones), if taken in large amounts at one time will concentrate in our tissues and can lead to cancer growth. Pyridoxine, or vitamin B6, is stored in the liver and in excess can lead to liver damage.
Then there are fat-soluble vitamins: vitamins A, D, E and K. Most of these are harmful if taken in excess. Vitamin A is stored in our liver, and too much can cause liver damage. Vitamin E is an antioxidant, but too much inhibits the binding sites for other antioxidants such as vitamin C, copper, zinc and selenium, which have other purposes, throwing off the body’s antioxidant system.
Vitamin D, on the other hand, is difficult to obtain in toxic amounts. Vitamin D is obtained primarily from the sun, fortified dairy products, fatty fish, and shiitake mushrooms. Unfortunately, many factors inhibit the synthesis of vitamin D even from those sources.
There is negligible synthesis of vitamin D from the sun between October and March in the Northeast. We are just too far away. Be grateful you weren’t a medical student at Tufts University in the 90’s because they were the subjects of this study. They were outside in bathing suits in January and no vitamin D synthesis occurred.
In the summer, we can obtain vitamin D from the sun, but sunscreen can limit synthesis. Overweight individuals sequester vitamin D in fat cells rendering it unusable by the body. This is a problem because vitamin D is linked with the body’s level of inflammation and vitamin D deficiency is linked with every disease we know of, including asthma, arthritis, cardiovascular disease, cancer and diabetes. As a dietitian, I suggest getting your nutrients from food, but taking a vitamin D supplement is an exception to the rule.
Then there are the coveted antioxidants. As runners, antioxidants are essential to stabilize the free radicals produced after a workout or long run. For men, it is important to consume antioxidants after a workout. Women, however, should not consume them right after a workout because it down-regulates the body’s antioxidant system (sorry, men, but women’s bodies don’t need as much help). Nevertheless, it is still important to have a high antioxidant intake overall.
Antioxidants are vitamins A, C, E, copper, zinc, selenium, and lutein. Food sources include fruits and vegetables, beans, nuts, seeds, shellfish, and egg yolks (yup, the yolks - so stop throwing the best part of the egg away!) You should obtain antioxidants from food for a few reasons. The first is that we haven’t perfected extrapolating the antioxidant property and putting it into supplement form. You won’t get the full benefit from a pill and you may suffer harmful effects such as hardening of the arteries.
Moreover, zinc and copper compete for the same binding sites. People often take zinc to stave off illness, but they take it indefinitely, precipitating a copper deficiency. A copper deficiency inhibits proper use of iron so anemia develops, which will not make running any easier.
And about iron: I work with many athletes who have issues with iron deficiency. Iron is lost when we sweat. We break down red blood cells in our feet when we run. And we lose iron from our gastrointestinal tract. That’s right - we poop it out. So we should take iron right? NO! Taking iron is complicated.
Iron is the opposite of an antioxidant. Iron can feed infection. Sometimes, we may appear to be iron deficient but what is going on is that our body is in a state of inflammation. Since iron feeds infection, our bodies secrete hepcidin to push iron into storage and reduce iron absorption. There may be plenty of iron in your body, but it’s in storage to protect you from more problems.
If you measure your iron during a heavy training season, your blood volume will be expanded, encasing the iron in your blood to appear lower than it really is. If you get your iron level checked after a hard workout, you may be inflamed, pushing the iron into storage. There are many other blood measures that can be taken before determining if an iron supplement is necessary.
These are just a few of many examples of the adverse effects of obtaining nutrients from supplements vs. food. When we eat our nutrients they are better absorbed because other nutrients can enhance the absorption. However, there are exceptions such as dairy foods, which, when eaten with iron-rich foods, impair the absorption. But we will discuss that next time.
The bottom line is this: eat a varied diet, moderate in all foods, and don’t rely on supplements. If you have conditions such as food allergies, celiac disease, Crohn’s disease, or reflux, there may be supplements you need, but that can be determined by working with your doctor or a dietitian.
Dr. DeLorenzo is the owner and founder of Nutrition for Optimal Performance
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