“Most vitamins are 'water-soluble,' so your body flushes out any excess that it does not absorb, but others are 'fat-soluble,' so they can build up to toxic levels when consumed excessively over time.” Getting too much of certain vitamins or minerals also can lead to unpleasant side effects like vomiting, diarrhea and ...
Any ingredient in a multiple vitamin supplement can be toxic in large amounts, but the most serious risk comes from iron or calcium. Additional risks are associated with large or toxic doses of calcium, vitamin D, and vitamin A.
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.
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.
The short and simple answer is: Yes! Vitamins C and D are commonly found together in multivitamins. They have complementary effects, which means that taking them together can better support your health. They're particularly beneficial to the immune system.
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.
Do not add too much vitamin C at the same time but should be divided into 3-4 times Drink/day at different times Avoid taking vitamin C at night before going to bed, because it can cause stimulation, excitement leading to insomnia.
But routinely getting an overload of vitamins and minerals can hurt you. Too much vitamin C or zinc could cause nausea, diarrhea, and stomach cramps. Too much selenium could lead to hair loss, gastrointestinal upset, fatigue, and mild nerve damage.
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. Also keep in mind that your body can only absorb 600 mg of calcium at a time—so if you're taking more, have one dose in the morning and one in the evening.
Vitamin C may destroy vitamin B12 (avoid large doses of vitamin C within one hour of taking oral vitamin B12). All B vitamins act synergistically and excess levels of one may lead to imbalance or deficiency in others. It is advisable to take B vitamins as a complex rather than as single substance supplements.
However, taking your supplements at night isn't a good practice because your digestion and metabolism slow down when you're asleep. This means that when you take vitamins at night, they are not absorbed as efficiently as during the day.
Neil Levin, a clinical nutritionist at NOW Foods, agrees that morning is best for multivitamins and any B vitamins. “Multivitamins tend to do best when taken earlier in the day, as the B vitamins in them might stimulate metabolism and brain function too much for a relaxing evening or before bed,” Levin says.
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.
Certain medications (bile acid sequestrants such as cholestyramine/colestipol, mineral oil, orlistat) can decrease the absorption of vitamin D. Take your doses of these medications as far as possible from your doses of vitamin D (at least 2 hours apart, longer if possible).
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].