Health Watch: How to make vitamins work better for you

With more than 90,000 supplements on the market, the vitamin industry is a big one in the U.S. Since 1999, the National Institutes of Health has spent $2.4 billion researching vitamins and minerals. The jury is still out on how effective all these supplements are, but there are steps consumers can take to optimize the efficacy of their vitamins.

50%t of adults take vitamins and supplements, but dieticians say we're not getting the most bang for our buck.

"There are ways to enhance the absorption, the efficiency of the vitamin and mineral supplement," explained Moe Schlachter, RD, CDE, a registered dietitian at Houston Family Nutrition.

One way to do that? Take fat-soluble vitamins like A, D, E and K with a high-fat meal.

"Those fat-soluble vitamins will be better absorbed with a meal that contains at least ten grams of fat or more," detailed Whitney Linsenmeyer, PhD, RD, LD, a registered dietitian at Saint Louis University in St. Louis, Missouri.

One study shows taking vitamin D with a high-fat meal increases absorption 32% more than with a fat-free meal.

"Some nutrients will enhance the absorption of others and then some nutrients will inhibit the absorption of others," Linsenmeyer told Ivanhoe.

Vitamin D increases the absorption of calcium, so take those together. Calcium and zinc both inhibit iron absorption, so it's best to take those separately.

Schlachter said, "caffeine can also inhibit absorption of certain nutrients."

People should avoid taking iron with coffee. Most vitamins with the exception of iron should be taken with food.

"When we're consuming these with foods, we also have those gastric juices and enzymes present that are helping us to absorb those nutrients optimally," explained Linsenmeyer.

Remember that all vitamins are not created equal. To ensure you're getting safe, high quality vitamins always look for the United States Pharmacopeia seal.

"The USP is really the saving grace, I would say, in the world of supplements," said Schlachter.

With $30 billion spent every year on dietary supplements, a little vitamin savvy can go a long way.

It's important to note that some vitamins and supplements can build up to toxic levels if you take too much of them, especially fat-soluble vitamins like A, D, E and K. Some vitamins can also interfere with medications prescribed by your doctor so it's important to let your doctor know about any supplement you take.

Contributors to this news report include: Stacie Overton, Field Producer; Roque Correa, Editor; Rusty Reed and Bruce Maniscalco, Videographers.