While most people pay attention to their macronutrients (protein, carbohydrates, and fat), they often forget about watching their micronutrients—the vitamins and minerals in foods. “Micronutrients are key to supporting energy metabolism, oxygen transfer and delivery, and tissue repair,” says Marni Sumbal, nutritionist and owner of Trimarni Coaching and Nutrition in Greenville, South Carolina.
If your body is a machine, think of micronutrients as the gears—they facilitate the metabolic reactions that help turn food into fuel, says Ingrid Skoog, nutritionist and instructor at Oregon State University’s College of Public Health and Human Sciences. And although all vitamins and minerals are essential to your overall health, a few are especially crucial for athletes. To optimize your performance, focus on these eight, and aim to get them (preferably) through real-food sources rather than supplements.
Iron
What It Does: Iron helps red blood cells carry oxygen to muscles, says Sumbal, which is critical for improved endurance. Research shows that regular endurance training leads to a greater daily loss of iron, making deficiencies common among the highly active. To combat this expedited rapid loss, the Food and Nutrition Board suggests a 30 percent increase in iron intake for people who exercise intensely on a regular basis.
Where to Find It: Oysters, clams, red meat, fish, raisins, tofu, lentils, and white beans are all great sources of iron. Another solid (and cheap) option: A cup of cooked spinach contains about 80 percent of the daily recommended allowance for men and 35 percent for women.
B Vitamins
What They Do: Each B vitamin—including folate, thiamin, riboflavin, niacin, B6, B12, pantothenic acid, and biotin—has a role in energy production, but many of them work together for greater impact, says Sumbal. Specifically, they break down carbohydrates into glucose for energy and help process fat and protein. “They’re like a flame to the fire,” she says. Among the B vitamins, B12 stands out for its function in red blood cell production and the synthesis of DNA. Since red blood cells are responsible for removing carbon dioxide from your body and carrying oxygen, it’s especially important that endurance athletes keep their B12 levels high.
Where to Find Them: Chicken, beef, leafy greens, eggs, milk, beans, and whole grains all contain most B vitamins. Animal sources are the best B12 sources, but vegans or vegetarians can also find it in fortified cereals and nutritional yeast.
Vitamin D + Calcium
What They Do: Vitamin D and calcium work hand in hand for bone health. Although calcium on its own will make your bones stronger and work as an anti-inflammatory, it won’t be fully absorbed without the help of vitamin D. Shortage of this vitamin is shockingly common in outdoor athletes, most of whom assume they’re getting enough from sunlight alone. “Especially if you’re a winter sports athlete, you may not be getting the exposure you think you are,” says Skoog.
Where to Find Them: Most dairy products—like cheese, milk, and yogurt—provide a great dose of both calcium and vitamin D. Since vitamin D is best absorbed when paired with fat, opt for a full-fat option rather than a fat-free alternative, says Sumbal. Salmon is another great source of both.
Vitamin C
What It Does: It’s known for fighting off sickness, and for good reason. Vitamin C is a major immunity booster, and research published in Medicine and Science in Sports and Exercise has shown that long-lasting exercise at a moderate intensity decreases immunity. Incorporate a few health-boosting foods into your diet to improve your ability to fight off sickness.
Where to Find It: Load up on foods like broccoli, peppers, kiwi, and oranges. Yellow bell peppers are chock-full of the stuff, with a large pepper containing almost four times the recommended daily allowance for men and fives times that for women.
Magnesium
What It Does: Magnesium plays a role in nerve and muscle function, including how the heart contracts, says Sumbal. It also assists in protein, fat, and carbohydrate synthesis and electrolyte balance. When there is not enough magnesium in the cells, the muscles and nerves can become stressed, causing cramping or restless legs and involuntary spasms, she says.
Where to Find It: To hit the recommended daily allowance of 420 milligrams for men and 320 milligrams for women, aim for a daily mix of deep-green leafy vegetables, nuts, seeds, and whole grains.
Potassium + Sodium
What They Do: Potassium is one of the three major electrolytes and works in conjunction with sodium to maintain cells’ membrane potential. That’s a fancy way of saying it’s largely responsible for proper muscle contraction, heart function, and communication between nerves. The two micronutrients also work together to maintain fluid balance in the body. During exercise, you lose electrolytes through sweat, which can lead to fatigue and muscle cramping, but potassium and sodium help restore proper hydration and keep those side effects at bay.
Where to Find Them: Bananas are the usual go-to for a dose of potassium, but a small white potato with the skin on contains almost double the banana’s potassium count. Other good potassium sources include oranges, beans, salmon, and milk. For a quick sodium fix, simply add a dash of table salt your food. Sprinkle a potato with salt for a quick one-two punch after an intense endurance session to rebalance electrolytes.