Many people who take vitamins and supplements grab a handful and toss them down the gullet first thing in the morning. But experts say that may not be the best time to take some nutritional supplements, so it’s important to know when to take them to get the most benefit.

“The best way to get all your nutrients is from food,” notes Dr. Ellen Kamhi, a medical school instructor and author of "The Natural Medicine Chest."

“But of course there is a large amount of scientific evidence that supports the use of supplements. There are many instances when your diet isn’t sufficient to provide all the necessary nutrients because of toxic growing conditions, the chemicals used in GMO crops, or simply poor eating habits.

“That being said, there are some ‘rules of thumb’ about the best times to take different kinds of vitamins and minerals.”

Kamhi recommends taking multivitamin and mineral combinations in the morning before breakfast. And she says NEVER to take a calcium-magnesium pill combination.

“The calcium will most likely be absorbed but will block the absorption of magnesium,” she tells Newsmax Health. “And if you take iron supplements, avoid ferrous sulfate. Choose ferrous chelate or fumerate instead.”

Other experts are even more specific in their directives:

Water-soluble vitamins. B vitamins and vitamin C, among other water-soluble vitamins, should be taken in the morning, preferably without food. “Take all the water-soluble vitamins before breakfast,” Dr. Robert Silverman, a certified clinical nutritionist with the American Clinical Board of Nutrition, tells Newsmax Health.

Fat-soluble vitamins. It’s best to take fat-soluble vitamins with food. These include vitamins A, D., E, K, and the minerals iron and magnesium should be taken with food.

Magnesium. Taking magnesium with food reduces the side effect of diarrhea and taking the fat soluble vitamins with food prevents stomach upset.

SAMe, CoQ10. “If you are taking the supplement SAMe, this also should be taken with food,” Silverman advises. “The important supplement co-enzyme Q10 needs to be taken with fat, so choose a healthy fat such as avocado and almonds to help the absorption of this nutrient.”

Calcium. Silverman recommends taking calcium supplements in the evening because it helps with muscle relaxation.

Fish oil pills. The popular omega-3 fatty acids in fish oil supplements may slow down the absorption of other medications and nutrients, according to the University of Maryland. So take this supplement at dinner time and avoid combining it with other medicines or nutritional aids.

DHEA. Holli Lapes, RD, with Life Extension, adds that certain hormones such as DHEA should be taken in the morning.

Antioxidants. “Lipoic acid, a powerful antioxidant, is another good one to take in the morning since it works best on an empty stomach,” Lapes adds. “But since an empty stomach is defined as 30 minutes before a meal or two hours after a meal, that could a flexible.”

Brain boosters. She adds that brain-boosting blends or formations like Cognitex should be taken in the morning to support memory, learning, and oxygenation to the brain throughout the day.

Digestive enzymes. People who take digestive enzymes should take them with the heaviest meal of the day, which for many Americans is dinner.

Sleep aids. Jason Boehm, a board-certified nutrition expert from Chicago recommends taking sleep-inducing supplements like L-theanine, inositol, or melatonin in the evening.

“But I prefer that my clients take all their other supplements with meals during the day for maximum benefit,” he says. “And since I recommend that breakfast is the largest meal of the day, that’s when I recommend most of the supplements be taken.

“I also advise that for people taking large amounts of a supplement such as a multivitamin to divide their dosage during the day to regulate the benefits.”

Kamhi adds that since we are all different and may be taking certain medications, it is always best to discuss your supplements with a trained healthcare provider for individual information.