The value of vitamins and minerals for athletes
Many athletes believe that their success hinges on taking “extra” of certain nutrients, including potassium, calcium, iron and zinc. Coaches, trainers and parents often advise athletic-minded teens to take supplements to meet the extra demands placed on the body during workouts and competitions. In reality, eating a varied diet is the simplest and most effective way to supply the body with the fuel (calories) and 40-plus nutrients that it requires daily for optimal health and performances.
Potassium partners with another highly discussed nutrient, sodium, to balance fluid and electrolyte levels in the body. It’s important to get enough potassium since it aids the body in maintaining a normal water balance between the cells and body fluids (blood) at rest and during exercise.
Being properly hydrated helps the heart to beat normally and it improves the body’s ability to cool itself. It does this by transporting the heat generated during exercise by working muscles (via blood) to the skin where it can evaporate. Potassium also helps muscles and nerves communicate.
Along with meeting normal daily needs (3,500 milligrams) for potassium, active teens and adults need to replace the potassium they lose through sweating, although it’s a much smaller amount compared to sweat sodium losses.
Potassium supplements are rarely necessary, however, because so many common foods supply potassium. Beyond bananas, other potassium-rich options include baked potatoes, winter squash, dairy foods like low-fat milk and yogurt, orange juice, cantaloupe, prunes, tomato juice, pinto beans, and leafy greens, like spinach and collard greens.
Besides building strong bones and teeth, calcium helps muscles to contract, nerves to send messages and blood to clot properly. The requirement for calcium is higher during the teen years, where they require 1,300 milligrams daily or about four servings. Those ages 19 to 50 require 1,000 milligrams daily, and 1,200 milligrams for women over 50 and men over age 70.
Nearly half of all bone is formed during the teenage years, particularly ages 11 to 15. According to a 2010 study published in The Journal of Nutrition, however, 86 percent of teen girls do not get enough calcium from their daily food choices.
Consuming adequate calcium can help protect athletes from season-ending stress fractures, but only if the athlete is consuming enough calories to fuel their activity level. For females, this means producing enough estrogen to maintain a regular monthly menstrual cycle and for males, maintaining an age-appropriate blood testosterone level. While calcium is used to make bone, it’s estrogen and testosterone that enable the body to hold on to or keep bone.
Food calcium never affects the body’s blood calcium level. If the foods a person chooses to eat don’t supply enough calcium, the body steals from the only source it has — bones and teeth. At 300 milligrams a serving, milk (1 cup), yogurt (8 ounces) and cheese (1 ounce) are calcium jackpots, as are foods made with milk, such as puddings and soups. Other calcium-rich foods include fortified foods such as orange juice and soy milk, firm tofu if processed with calcium sulfate, canned fish with soft bones, including salmon and sardines, and dark-green leafy vegetables, such as kale, turnip greens and bok choy.
Iron is essential for forming hemoglobin and myoglobin, the oxygen-carrying compounds in blood and muscle. Without enough iron to produce healthy red blood cells (18 milligrams daily for females, 8 milligrams for males), iron-deficiency anemia results, leading to fatigue, poor recovery and subpar performances, on the field and in the classroom.
Eating an iron-poor diet is the leading cause of iron-deficiency anemia, followed by blood loss or certain intestinal diseases that affect how the body absorbs iron. Athletes who are dieting or under-eating, vegetarian or vegan, train at high altitude, have increased losses in sweat, menses or their sport involves a great deal of pounding or foot-strike (which damages red blood cells) are most at risk for developing iron deficiency anemia.
Certain individuals, on the other hand, have a genetic disorder called hemochromatosis or iron overload, which causes them to absorb too much iron from the food they eat as well as from any supplements they take. The excess iron is stored in organs, especially the liver, heart and pancreas, leading to life-threatening conditions such as cancer, abnormal heart rhythms and liver damage.
Animal foods, such as lean red meat, dark poultry and seafood, provide the most readily absorbable and usable form of iron (known as heme iron), especially as compared to the non-heme iron from plant sources, such as dark leafy greens, dried fruit, beans and lentils, whole grains and soy foods. The iron supplied by supplements is also non-heme iron.
Athletes who wish to take supplemental iron to avoid iron depletion (during periods of intense training or high mileage, for example) should always work with their health care provider and have their iron status monitored with the appropriate blood tests.
Zinc is essential for normal growth, energy production and keeping the immune system strong. It also plays a key role in the building and repair of muscle tissue, including repairing the cellular micro-damage caused by daily workouts. Female athletes require 8 milligrams daily and males need 11 milligrams.
Athletes who consume enough lean, quality protein from animal sources daily typically will get enough zinc. Athletes choosing to limit or avoid red meat, as well as vegetarian and vegan athletes, are most at risk for consuming too little zinc.
Animal foods, such as lean meats, fish, poultry, shell fish and oysters, and whole grains and legumes (e.g., kidney, black, and pinto beans) are all zinc-rich foods. Athletes are cautioned against taking single-dose zinc supplements. Unnecessary zinc supplementation may lead to low HDL cholesterol (the good kind) and nutrient imbalances. Zinc, for example, interferes with the absorption of other nutrients such as iron and copper.
Nutritional Value is a column that focuses on athlete health and wellness. It appears regularly in Coach & Athletic Director magazine.