Close to 75 percent of adults in the U.S.—that’s about 170 million people—take dietary supplements, this according to the 2018 Consumer Survey on Dietary Supplements by the Council for Responsible Nutrition. The top reason: to support overall health, wellness and energy.

To get the most benefit from supplements, it’s helpful to understand how to best help your body absorb them. We caught up with Kroger’s Molly Hembree, R.D., L.D., and pharmacist Laura Clark, Pharm.D, R.Ph., for their supplement absorption tips on their top-three recommended supplements for the average American adult.

“We always want to be looking at our dietary pattern first and adjusting nutrient needs with food, before reaching for a bottle to make up for any nutritional gaps.” –Molly Hembree, R.D., L.D.

Calcium

Hembree notes that calcium is a nutrient that Americans tend to fall short on.

Calcium Absorption tips

“Strive to get calcium in a calcium citrate form versus calcium carbonate,” says Clark. Although a carbonate is fine, it requires stomach acid to digest, so you need to take it with food. “With a citrate, you can take it on an empty stomach, and it will be just as easily absorbed as if you just ate.”

Know that your body can uptake only about 500 mg of calcium at a time. “So, if you take a supplement that has 750 mg of calcium, your body won’t use that extra 250 mg very well,” says Hembree.

Vitamin D

One of the best natural ways to get vitamin D is exposure to sunlight, but lack of time outside or using sunblock (or a combination) limits how much we get, says Hembree.

Vitamin D Absorption tips

In supplement form, vitamin D is best absorbed in combination with calcium, notes Hembree. “If you see them together in a supplement, it’s a perfect harmony,” she says.

Unfortunately, vitamin D is not abundant from food outside of fish and egg yolks. But, according to Hembree, a number of foods are fortified with vitamin D, such as milk, cereal, margarine and dairy-alternative beverages.

“Getting your Vitamin D BY Spending 5–30 minutes in the sun, two times a week, with your limbs exposed, is enough,” says Hembree.

Iron

“In general, here in the U.S., we tend to fall short on enough iron in our diet,” says Hembree.

Iron Absorption tips

Iron is absorbed better when:

Consumed with a vitamin C source. “Wash your iron supplement down with a glass of orange juice,” says Hembree. Or when cooking, because iron is naturally found in meat products and legumes, cook meat or beans with vitamin C–rich vegetables, like bell peppers or broccoli. Another good bet is mixing strawberries (high in vitamin C) with an iron-fortified cereal at breakfast.

Taken in heme form. “There are two different forms of iron in our diet: heme and nonheme,” explains Hembree. “Heme iron is more readily absorbed and comes from animal products—meat, poultry, fish—with some found in eggs and dairy.” Nonheme iron comes from sources like dark leafy greens, beans and nuts, and whole grains. “If you follow a vegetarian or vegan diet, you can still get iron from these foods, but you’ll need to keep in mind that you may need to eat more to have a similar effect to what you would get from meat and fish.”

Does the form matter for supplement absorption?

Is it better to take capsules? Pills? Coated? Uncoated? Powder? Liquid?

“There isn’t a dramatic difference in delivery methods,” says Clark. “As a pill enters the body, it’s going to be broken down by our stomach acid no matter what. And liquid will absorb faster but not better.” Hembree adds that for certain people, injections of certain vitamins like D or B12 are appropriate if there is a diagnosed deficiency. And vegetarians and vegans will want to avoid capsules, which are made with gelatin.