Food

What Is Bioavailability?

Bioavailability reveals which nutrients on the plate work in harmony and which battle absorption.

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According to the most recent national guidelines, we should get most of our nutrients from the food we eat. Yet a dietary assessment by the Department of Health and Human Services and the USDA shows that most Americans fall short of the recommended intakes for fruit, vegetables, whole grains, and dairy.

Why does this matter? Vitamins and minerals, though you might not think about them daily, kick-start tons of bodily functions that runners rely on to keep going. B vitamins, for example, are integral to metabolizing carbohydrates and turning amino acids into protein. How our bodies ingest and absorb those nutrients from the foods we eat can be impacted—which experts refer to as bioavailability.

“Bioavailability is the amount of a nutrient that is absorbed and utilized by the body, compared to the amount that is actually consumed,” says Stephanie Ostrenga Sprague, food safety educator at Michigan State University Extension. It mostly has to do with our digestion mechanisms, which can be affected by gender, age, and other genetic factors, like menopause or pregnancy.

The nutrients we eat can also have varying degrees of bioavailability depending on factors such as the structure of food (think tough fibrous vegetables and proteins), the processing or treatment of a particular food, and interactions between various nutrients and foods (tea and coffee, for example, are rich in oxalates, which can inhibit both calcium and iron).

The good news: Whether you eat a balanced, nutrient-packed diet or you’re struggling to get your servings of fruits and veggies, simple changes can help you get the most from your food.

Try these seven tips before you make a mad dash to the supplement aisle.

Chop up your salad.

Get more folate by chopping or mincing your dark, leafy greens. (Chopping breaks down the rigid tissue structure that holds folate, releasing more of it.)

Increase your iron.

Iron from vegetables is not as easily absorbed as iron from meat. Adult women need approximately 18 milligrams of iron daily (8 for women 51 or older); if you eat a plant-based diet, you’ll need nearly twice as much iron to get an equal absorption. Adding a larger volume of iron-rich vegetables like spinach, sweet potatoes, broccoli, and kale to your diet can help.

Get your vitamin C.

Pair a hard-boiled egg or fortified breakfast cereal with orange juice or a grapefruit half. Foods high in vitamin C increase the absorption of iron.

Mix in meat protein.

Heme iron (found in meats) increases the iron absorption of non-heme iron (from plants), so combining them will give you the most bioavailable iron. Add chicken to your spinach salad for an iron-rich combo.

Soak your oats.

Phytates, commonly found in grains and seeds, can inhibit the absorption of some dietary minerals. Humans don’t have a sufficient amount of enzymes to break down phytates naturally. Soaking your oats in water is a way to reduce the presence of phytates and increases the absorption of minerals like zinc and iron.

Use a little oil.

Foods high in carotenoids (an antioxidant capable of reducing harm from free radicals, like pollution), such as squash or carrots, are more soluble when cooked in 3–5 grams (about a teaspoon) of oil.

Nuke your spinach.

Cooking spinach allows the body to extract more vitamin A from it—but cooking too long can leach its nutrients. Try quickly nuking it: Place fresh spinach leaves in a microwavable bowl, add a thin layer of water, and cover. Microwave approximately two minutes.