This is an excerpt from Nancy Clark's Sports Nutrition Guidebook-5th Edition.
Vitamin and Mineral Supplements
What are vitamins and minerals? Vitamins are metabolic catalysts that regulate biochemical reactions within the body; they are found in the plants you eat and are created by the plants themselves. The peak of nutrient value occurs at peak ripeness; hence, buying freshly picked local produce can offer slight nutritional benefits. Minerals are natural substances that plants must absorb from the soil. If the soil is void of the needed minerals, the plant fails to thrive or yields small fruits or vegetables that have a poor appearance.
Your body cannot manufacture vitamins or minerals, which is why you must obtain them through your diet. By eating a variety of wholesome foods, you can consume the balance of vitamins and minerals needed for optimal health and performance. To date, 14 vitamins and 15 minerals have been discovered, each with a specific function. Here are a few examples:
- Calcium maintains the rigid structure of bones.
- Sodium helps control water balance.
- Iron transports oxygen to the muscles.
- Thiamin helps convert glucose into energy.
- Vitamin D controls the way your body uses calcium.
- Vitamin A is part of an eye pigment that helps you see in dim light.
Many of my clients take vitamin supplements. They assume that active people need more vitamins and supplements to pave the way to better health and performance. This is not the case. You can get the recommended amount of most nutrients (except possibly iron) by eating 1,500 calories of a variety of foods. This amount not only prevents nutrition deficiencies but also is a good investment in good health. You are unlikely to live any longer if you take vitamin supplements (Macpherson, Pipingas, and Pase 2012).
Although you do need adequate vitamins and minerals to function optimally, no scientific evidence to date proves that extra vitamins and minerals offer a competitive edge. Despite claims to the contrary, vitamin supplements do not enhance performance, increase strength or endurance, provide energy, or build muscle in healthy, active people. Nor does exercise significantly increase your vitamin and mineral needs. Exercise does not burn vitamins, just as cars don't burn spark plugs.
According to the International Olympic Committee (IOC 2011), the best way to get all the needed vitamins, minerals, and protein is to eat a variety of foods from all the food groups. Although supplements may be appropriate in certain situations, athletes should plan to maximize performance by eating quality foods. Taking a general multivitamin is unlikely to be harmful, but high doses of vitamin C, vitamin E, beta-carotene, selenium, and manganese might negatively suppress the body's immune system.
Keep in mind that the more you exercise, the more you eat. Compared with inactive people with smaller appetites, most athletes consume more calories and therefore more vitamins and minerals. Deficiencies are more likely to occur in sedentary people who eat very little, such as elderly people, than in active people who eat hefty portions.
Vitamin and mineral deficiencies do not develop overnight but over the course of months or years, such as can happen in a person with anorexia or someone who eats an inadequate vegetarian diet. Your body actually stores some vitamins in stockpiles (A, D, E, and K - the fat-soluble vitamins) and others in smaller amounts (B and C - the water-soluble vitamins). Most healthy people have enough vitamin C stored in the liver to last about six weeks. One day of suboptimal eating will not result in a nutritionally depleted body.
Paul, a triathlete, had heard that exercise increases harmful free radicals (particles that can cause oxidative damage and cancer). He was told to take supplements of cancer-protective antioxidants, including vitamins C and E, beta-carotene, and selenium. Little did he realize that high doses of antioxidants can sometimes turn into pro-oxidants (Nieman, D., D. Henson, S. McAnulty, et al. 2002) and blunt the training response (Ristow, M., Zarse, K. and Oberbach, A. et al. 2009). A good reason to get antioxidants from food is that food contains them in the right amounts (as well as other nutrients the body needs).
By eating a variety of wholesome fruits, vegetables, whole grains, lean meats, and low-fat dairy foods, you will consume the vitamins and minerals you need. As a bonus, many of today's foods (including energy bars and breakfast cereals) are highly fortified, so many active people actually consume far more vitamins and minerals than they realize, further negating the need to take supplemental pills. For the most part, the people who take vitamins are health conscious, eat well, and do not need supplements. Table 11.1 shows some commonly eaten sources of several vitamins and minerals.
Are Supplements Health Insurance?
Although taking a simple multivitamin is unlikely to hurt your health, does taking vitamin supplements improve your health if you already have a good diet? In a review of carefully controlled research studies on the impact of vitamin supplements on cancer, heart disease, cataracts, or age-related macular degeneration and hypertension, the U.S. National Institutes of Health concluded that "the evidence is insufficient to prove the presence or absence of benefits from use of multi-vitamin or mineral supplements to prevent cancer and chronic disease" (Huang et al. 2006; National Institutes of Health 2007).
The latest results of carefully conducted clinical research suggest that most supplements, including vitamins, are not as effective as hyped. That's because much of the hype stems from observational research studies that do not show cause and effect. That is, people who take vitamin supplements tend to be health conscious in the first place. So when you hear that people who take vitamin E pills have less heart disease, you need to wonder whether those people were compared against (less-health-conscious) people who chose to not take vitamin E, or against randomly chosen people.
The American Cancer Society recommends getting vitamins from a healthy diet, and if you choose to take a supplement, take one with 100 percent of the daily value (DV) but not more. Taking a large dose of a single vitamin might upset nature's balance because vitamins work synergistically.
Antioxidants (vitamins A, E, and C, and beta-carotene) have shown potential harm for athletes and no benefits. For example, a review of multiple studies shows that more than 1,000 milligrams of vitamin C might hinder hurt athletic performance (Braakhuis 2012). The consensus is that daily high-dose antioxidant vitamin supplementation is unlikely to be of real practical benefit (Davison, Gleeson, and Phillips 2007).
Taking a multivitamin and mineral supplement does not compensate for a high-fat, low-fiber, junk food diet. Nor should it allow you to rationalize eating suboptimally because you are overconfident about your nutrient intake. The information in chapters 1 and 2 can help you make smart food choices that provide the nutrients you need. If you choose to take a vitamin supplement, look first at your daily diet to see whether you are already consuming these vitamins through highly fortified foods such as breakfast cereals.
Read more from Nancy Clark's Sports Nutrition Guidebook, 5th Edition by Nancy Clark.