Jul 26, 2018
Vital Vitamins
Lisa Dorfman

When meat is eliminated from the diet, certain vitamin and mineral levels must be carefully monitored. Those who are new to vegetarianism may have been getting most of their vitamin B12, iron, calcium, and zinc from animal products without knowing it.

Studies have found that zinc levels are typically lower in vegetarians than omnivores, which is not surprising since 50 to 70 percent of zinc in our diet regularly comes from meat and dairy. Zinc is essential for protein synthesis, immune system function, and new blood cell formation.

The recommended daily amount is 11 milligrams for men and nine milligrams for women, but these values may be too low for competitive athletes, since strenuous exercise can lead to increased zinc loss through sweat and urine. To further complicate matters for vegetarians, a plant compound called phytate found in the hulls of many nuts, grains, and seeds may inhibit zinc bioavailability in humans.

According to The American Dietetic Association’s position paper on vegetarian diets, one way to increase zinc absorption from beans, grains, and seeds is to soak them in water before eating them. Another effective method is to eat fortified cereals and other zinc-rich foods together with citrus fruit, which helps promote absorption.

Calcium recommendations for active males and pre-menopausal females are typically 1,200 to 1,500 milligrams daily for adolescents and 1,000 milligrams for adults. Calcium is essential for bone integrity and also plays an important role in circulatory and nervous system health. Low calcium intake can increase the risk of stress fractures, especially in amenorrheic female athletes.

Some research suggests that vegetarians may have lower calcium needs than omnivores because the higher protein and sodium intake typical of meat eaters leads to greater calcium excretion, but the jury is still out on that theory. In any case, there’s no need to gamble, since calcium is easy to find in dairy products and fortified dairy alternatives like soy, rice, and almond milks, tofu, juices, shakes, and greens.

Iron is critical for all athletes because it synthesizes hemoglobin and myoglobin, which transport oxygen to muscles. Athletes and growing adolescents are at particularly high risk for iron deficiency, partly because of the natural demands of physical growth and partly due to iron loss through heavy sweating. Another iron-related issue is hemolysis, or the destruction of red blood cells, which can be caused by high-volume endurance training.

As with zinc, the standard daily recommendation for iron consumption (which ranges from eight to 18 milligrams per day depending on age and gender) is likely too low for vegetarians because of the lower absorption rate of non-meat iron sources. The form of iron found in plants, called non-heme iron, is less bioavailable than the heme iron found in meat and fish.

Many vegetarians take an iron supplement to ensure they get an adequate supply of this vital mineral. But it’s not hard to get enough iron in the vegetarian diet through beans, fortified cereals, greens, and dried fruits. Consuming iron-rich foods along with citrus fruit and other fruits and vegetables rich in vitamin C, such as broccoli, red and green peppers, and strawberries, also helps to increase iron absorption.

One other nutrient for which vegetarians may be at risk of deficiency is B12. Found only in animal products and foods fortified with it, B12 is an important coenzyme required for the normal metabolism of protein, carbohydrates, and fats. The daily recommendation is 2.4 micrograms, which can be obtained through fortified cereals, bars, shakes, rice and soy milk, and nutritional yeast. If a vegetarian athlete is unsure of their B12 level, a simple blood test can determine if they have a sufficient supply.

Athletes who choose the vegetarian lifestyle can give themselves an edge over their meat-eating peers. Whether they do it for health reasons, moral reasons, or simply personal preference, as long as they monitor their intake of key macro- and micronutrients, they’re well positioned to achieve optimal fueling for performance and health.

Lisa Dorfman, MS, RD, CSSD, LMHC, is a personal nutritionist for hundreds of high school athletes and teams and dozens of professional athletes, including those in the NFL, MLB, PGA, USTA, US Boxing, USA Taekwondo. She was the US Sailing Olympic and Paralympics Team Nutritionist for the 2008 Olympics.

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