Combining multiple supplements or taking higher-than-recommended doses can increase the risk that they can cause harm, said Kitchin. "You really can't get toxic doses of nutrients through food, but you can absolutely get toxic doses through supplements," Kitchin said.
Large doses of minerals can compete with each other to be absorbed. Don't use calcium, zinc, or magnesium supplements at the same time. Also, these three minerals are easier on your tummy when you take them with food, so if your doctor recommends them, have them at different meals or snacks.
The best time to take fat-soluble vitamins like vitamin D, A, and K is with a meal containing fats. You should take water-soluble vitamins like vitamin C, B12, and B6 in the morning on an empty stomach. Take multivitamins or prenatal vitamins with a meal or snack containing fat and a glass of water.
6 Symptoms may include kidney stones, nausea, recurrent vomiting, constipation, excessive thirst, excessive urination, confusion and weight loss. Taking high doses has also been linked to cancer risk, heart problems, and an increased risk of bone fractures.
Vitamin C and Vitamin D are two essential nutrients that play important roles in the body and help to maintain overall health and wellness. You may be wondering, “Can I take Vitamin D and C together?” The answer is… Yes. In fact, when taken together, they're a powerful combo that can support the immune system.
Fat-soluble and water-soluble vitamins
For example, although it's safe to take vitamin D with vitamin B12, it's not advisable, says Virgilio Sanchez, MD, a board certified family medicine physician at Conviva Care Center in Miami, Florida.
Combining multiple supplements or taking higher-than-recommended doses can increase the risk that they can cause harm, said Kitchin. "You really can't get toxic doses of nutrients through food, but you can absolutely get toxic doses through supplements," Kitchin said.
Mayo Clinic suggests aiming to leave at least one to two hours between vitamins. “I usually tell people to take them at a separate meal,” says Brissette.
“Digestion slows down during sleep, so taking your nutrient supplement late at night would not be associated with an efficient absorption.” Neil Levin, a clinical nutritionist at NOW Foods, agrees that morning is best for multivitamins and any B vitamins.
Supplementing vitamin B6 may improve sleep quality and duration. A 2019 study also found that taking a supplement of magnesium, melatonin, and vitamin B complex for 3 months improved sleep and helped treat insomnia.
Magnesium assists in the activation of vitamin D, which helps regulate calcium and phosphate homeostasis to influence the growth and maintenance of bones. All of the enzymes that metabolize vitamin D seem to require magnesium, which acts as a cofactor in the enzymatic reactions in the liver and kidneys.
Some studies suggest that the body may not be able to absorb vitamin K as efficiently when taken with vitamins D and E. As a result, taking a large dose of these three vitamins together may prevent vitamin K from clotting the blood effectively [7].
Interactions. Possible interactions include: Aluminum. Taking vitamin D and aluminum-containing phosphate binders, which may be used to treat high serum phosphate levels in people with chronic kidney disease, might cause harmful levels of aluminum in people with kidney failure in the long term.
Vitamin C (ascorbic acid) supplements.
Taking vitamin B-12 with vitamin C might reduce the available amount of vitamin B-12 in your body. To avoid this interaction, take vitamin C two or more hours after taking a vitamin B-12 supplement.
The fat-soluble vitamins A and D are the most likely to cause toxicity symptoms if you consume them in high amounts.
Vitamin D toxicity is usually caused by large doses of vitamin D supplements — not by diet or sun exposure. That's because your body regulates the amount of vitamin D produced by sun exposure, and even fortified foods don't contain large amounts of vitamin D.
Some vitamins work best with or after a meal (especially ones containing fat), while others should be taken on an empty stomach. Certain individual nutrient supplements (such as mineral supplements) shouldn't be taken together often because they affect the absorption of one another such as Iron and Calcium.
Take your multivitamin with food.
Because certain vitamins are helpful only when taken with food, it's best to take your multivitamin with a meal or snack. Vitamins A, D, E and K are fat-soluble, meaning your body can absorb them only when they're digested with fat.
You can—but it's probably not a good idea. For some supplements, optimal absorption can depend on the time of day taken. Not only that—taking certain vitamins, minerals, or other supplements together can also reduce absorption and may result in adverse interactions, which can be harmful to your health.