If you eat a cup of yogurt and the label says it has 300 mg of calcium, don’t assume that’s how much of the mineral your body will absorb. You’ll actually get just under 100 mg of calcium, on average, from the yogurt.

This kind of disconnect between what foods contain and what they give you comes as a surprise to many people—even those who pride themselves on eating wholesome, fresh foods that are known to be packed with nutrients.

Why it matters:The bioavailability (the amount of nutrients your body actually absorbs) of foods can vary widely depending on which foods you eat and how they are prepared—and even how they’re combined with other foods. Absorption of nutrients also can be affected by some health conditions, such as autoimmune diseases and digestive problems, and by certain medications, such as antacids and some antibiotics. To get more of these nutrients from the foods you eat…


You need calcium for healthy blood pressure and to keep your muscles moving and your bones strong. Yet many Americans don’t get enough.

Dairy products, such as milk, yogurt and cheese, are widely considered to be our primary sources of calcium. But the truth is, only about 30% of the calcium in most dairy products is absorbed by your body.

To get more calcium:Eat more greens. Some varieties have nearly double the calcium bioavailability of dairy foods.

Examples:You will absorb about 61% of the calcium in broccoli…59% of the calcium in kale…and 54% of the calcium in bok choy. Even though these greens do not contain as much total calcium as dairy products, when you factor in the higher bioavailability of these plant foods, you’ll see that they can be excellent sources of the mineral.

Just make sure you get the right greens if you’re trying to maximize your calcium absorption. The calcium is poorly absorbed from some greens, such as spinach and Swiss chard, that contain oxalic acid or phytic acid. These chemical compounds bind to calcium and other minerals, reducing their absorption by the body. Spinach and Swiss chard are, however, good sources of iron and folate.


Allicin, one of the chemical compounds that gives onions and garlic such a powerful smell, has been linked to lower cholesterol, better blood pressure and a reduced risk for heart disease and some cancers.

To get more allicin:Mince fresh garlic and onions. Mincing (rather than slicing or coarse chopping) releases more of an enzyme that interacts with a different compound in onions and garlic to trigger the formation of allicin.

Also helpful:After mincing, leave the onions or garlic on the cutting board for about 10 minutes. This short time-out allows the allicin-producing process to continue.


Carotenoids are the substances that give tomatoes, carrots and other brightly colored produce their brilliant hues. The most studied carotenoids, such as lycopene and beta-carotene, have been linked to lower rates of cancer, heart disease and eye diseases such as cataracts. Raw produce is rich in carotenoids, but you’ll generally absorb even more when the produce is cooked—the heat helps break down the cell walls so that the nutrient can be released.

To get more carotenoids:Instead of eating raw tomatoes, simmer them in a sauce. Also, cook carrots to allow more lycopene to be released. Spinach and kale release more beta-carotene when cooked.

Helpful:Buy processed tomatoes—they actually have more lycopene than fresh. But use tomato paste and tomato sauce in glass jars rather than canned varieties, which can expose you to bisphenol A (BPA), an industrial chemical that’s in many metal cans and plastic bottles. It has been linked to cancer, heart disease, diabetes and other health problems.


While cooking tomatoes and carrots coaxes optimal absorption, it’s best to eat cruciferous vegetables, such as broccoli and cabbage, raw to get their cancer-fighting benefits. Cruciferous vegetables contain compounds called glucosinolates that help protect against cancer. Boiling these veggies for nine to 15 minutes results in a 20% to 60% decrease in glucosinolates, which are leached into the water. And steaming or microwaving cruciferous vegetables on high may deactivate myrosinase, an enzyme that breaks down glucosinolates into compounds that may eliminate carcinogens.

To get more glucosinolates: Eat cruciferous veggies raw or microwave on low power.


All of the fat-soluble nutrients and antioxidants—such as vitamin E, beta-carotene and lycopene—require a little bit of fat in order to be absorbed by the body. The average meal contains plenty of fat to get the job done.

But if you’re eating, say, a simple salad and want to ensure that you absorb the most nutrients, a small amount of added fat will help. Recommended: Have no more than 10% of calories from saturated fat a day.

To get more fat-soluble nutrients: Toss some healthful fat-containing foods into your salad—good choices include cooked grains (such as quinoa), slivered nuts and/or a few olives. You’ll also be adding exciting flavors!

The Truth About Iron

The majority of Americans get plenty of iron from eating meat, so most are not deficient in this mineral. Exception: Low iron is more likely to occur in people who have ulcers or other conditions that cause bleeding or women with heavy periods. Note: Having too much iron has been linked to heart disease, cancer and diabetes.

To get more iron if you need it: The nonheme iron in plant foods—found chiefly in dark green vegetables—is less well absorbed than the heme iron in meats. To get more iron from greens such as spinach and Swiss chard, season them with a little vinegar or lemon juice. Acidic ingredients enhance the body’s ability to absorb the iron in plant foods.