As summer sprints out of the starting blocks, active people can match it stride for stride by vowing to eat more nutrient-dense foods. That means plenty of fruits, vegetables and whole grains on the training table.
One of the biggest reasons to stay the course of good nutrition during the hot-weather months is to make sure you get enough minerals. While representing only 4 percent of total body weight, these inorganic substances–meaning they are neither vegetable nor animal–are jump-starters of their own right in how the body uses carbohydrates, protein and fats. They are heavyweights when athletic performance is the measurement.
A quick review helps make the case for the elementary advice to get five daily servings of fruits and vegetables, plus six to 11 servings of grains. Each of these food groups provides a lot of necessary minerals.
Minerals perform three duties especially important to active people, says Hank Lukaski, a researcher at the U.S. Department of Agriculture regional nutrition center in Grand Forks, N.D.
1. Minerals regulate how the body uses carbohydrates, protein and fats for fuel. During exercise, the body calls upon minerals such as iron (which transports oxygen) and magnesium (vital in processing carbohydrates) to help burn the fuel. For the most part, the minerals are then eliminated through the kidneys rather than reabsorbed by cells, making it essential for athletes at all levels to replenish their supplies.
2. Though different from what you might find in a wall switch, the body’s electrical system governs such critical functions as nerve impulses and muscle contractions. Minerals that regulate the body’s electrical activity–especially sodium, potassium, chloride and magnesium–are called “electrolytes.” Sweating is the most common way to lose electrolytes.
3. Minerals are involved in the development and maintenance of bones and muscles. Most people know that calcium is key for bone health, but Lukaski cites three major international studies that show low amounts of copper, zinc or manganese make it difficult to stave off the bone loss that becomes more rapid in women after age 50 and men after 65.
And although protein is revered by weight lifters for its role in helping muscles recover and grow after workouts, the synthesis of protein is impossible without minerals. For example, zinc helps remove carbon dioxide waste from your muscles, which speeds recovery.
Summer weather presents unique seasonal problems with mineral retention. Perspiration and dehydration are the fastest ways to develop deficiencies or even just dip to levels that diminish sports performance. Barbara Day, sports nutritionist for University of Louisville athletic teams and a consultant with the U.S. Navy SEALs, says there is no one mineral among the 22 the body uses that should be emphasized over others. But she does categorize calcium, iron, magnesium, phosphorous, sodium, potassium and zinc as most important.
“You should always strive for a balance of minerals,” says Day, author of “High Energy Eating: Sports Nutrition Workbook for Active People (Apple a Day, $17.95). “The best route is eating a variety of produce and grains.”
Relying on nutritional supplements is not advisable because too many people concentrate on, say, taking enough calcium (particularly women concerned about bone strength) and iron (to fight off fatigue). Although calcium represents nearly half of all minerals in the body when measured by weight, an active person can “run out of gas” more rapidly by not getting enough electrolytes during and after summer workouts.
“When people sweat, they lose sodium chloride and potassium,” Lukaski says. “They can get it back by eating fruits and vegetables, plus salting their food to taste.” Plain old table salt is sodium chloride.
Salting your food is close to heresy among some health-conscious individuals who fear its effects on blood pressure. But unless a person suffers hypertension or kidney disease, Lukaski says, trusting your taste buds is a reliable way to meet sodium needs.
“We have a taste acuity that tells us when to seek more salt in the diet,” Lukaski says. “We should trust it during the summer months.”
Day says new research presented at last month’s annual meeting of the American College of Sports Medicine indicates that sodium might be more necessary to muscle recovery than any other mineral. But that doesn’t mean active people should return to the outdated method of taking salt tablets as much as maybe grabbing a snack bag of pretzels or a sports drink with sodium (look for 100 milligrams per 8 ounces).
As it turns out, recent studies show that inadequate calcium intake is the most significant determinant of high blood pressure and hypertension. Lu-kaski is hesitant to attribute such effect to any one mineral, explaining that substances work together for best results in the body. Several combinations are synergistic, he said: sodium and potassium; calcium and phosphorus; zinc and copper and manganese.
Eating a range of fruits, vegetables and grains can provide ample amounts of minerals, Lukaski says. (See chart for best sources.)
“People might drink one type of juice and eat lots of salad with romaine lettuce,” he says. “Those are healthy choices, and you get water for fluid replacement, but you will probably come up short on getting enough minerals.”
No summer nutrition column would be complete without mentioning the importance of drinking water: Drink it even when you’re not particularly thirsty. Day adds a couple of precautions about other summertime fluids.
“Watch your intake of soft drinks,” she says. “Too much soda can mess up your ratio of calcium and phosphorus.
“On the plus side, iced tea contains a fair amount of potassium. We drink a lot of it in the South.”
MINING FOR MINERALS
Here are the better food sources of important minerals, according to the book `The New Nutrition: From Antioxidants to Zucchini,’ by Felicia Busch.
– Iron: red meat, liver, cooked soybeans, egg yolks, clams, oysters, leafy green vegetables, iron-fortified grain products
– Calcium: dairy products, sardines, almonds, broccoli, spinach, soy products (tofu, tempeh), fortified orange juice, figs
– Potassium: 100 percent bran cereal, bananas, oranges/orange juice, dried fruit, spinach, squash, cooked tomatoes, chard, cod, flounder, peanut butter, potatoes, beans, yogurt
– Zinc: whole wheat, beef, pork, lamb, seafood (especially oysters), eggs. (Men should take it easy on red meat. Several major studies show a greater predisposition to prostate cancer in societies that eat a lot of it.)
– Magnesium: wheat bran, whole grains, spinach, broccoli, skin-on potatoes, dry beans and peas, lentils, nut butters, pumpkin seeds, non-fat yogurt, halibut
– Phosphorus: canned salmon with bones, mackerel, swordfish, chocolate milk, low-fat or non-fat yogurt
