A man in the UK was hospitalized after taking almost 400 times the daily recommended amount of vitamin D, highlighting once again the serious danger of taking unsafe doses of over-the-counter vitamins and supplements. "Vitamin D toxicity, also called hypervitaminosis D, is a rare but potentially serious condition that occurs when you have excessive amounts of vitamin D in your body," says Katherine Zeratsky, RD, LD. "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."
So what happens when too many vitamin D supplements are taken? "The main consequence of vitamin D toxicity is a buildup of calcium in your blood (hypercalcemia), which can cause nausea and vomiting, weakness, and frequent urination," Zeratsky says. "Vitamin D toxicity might progress to bone pain and kidney problems, such as the formation of calcium stones. Treatment includes stopping vitamin D intake and restricting dietary calcium. Your doctor might also prescribe intravenous fluids and medications, such as corticosteroids or bisphosphonates."
Vitamin D—in the correct amount—is crucial for good health. "We have known for a long time that vitamin D is important for bone health," says Marci A. Goolsby, MD. "One of the jobs of vitamin D is to help your gut absorb the calcium and phosphorus from your diet. These minerals in turn help build and maintain the strength of your bones. Low levels of vitamin D have been linked to stress fractures and other problems with the bones. But vitamin D has many other functions as well. I describe it to my patients as a delicate symphony of everything that goes on in your body. If one of the instruments — in this case, your vitamin D — is off, it can throw off the whole symphony."
Here is the official recommended daily amount of vitamin D, according to the National Institutes of Health.
Life Stage Recommended Amount
Birth to 12 months 10 mcg (400 IU)
Children 1–13 years 15 mcg (600 IU)
Teens 14–18 years 15 mcg (600 IU)
Adults 19–70 years 15 mcg (600 IU)
Adults 71 years and older 20 mcg (800 IU)
Pregnant and breastfeeding teens and women 15 mcg (600 IU)
Vitamin D is not the only vitamin that can cause serious health issues if incorrectly dosed: Here are five other supplements that can make you sick if you don't follow the recommended daily amounts. Read on—and to ensure your health and the health of others, don't miss these Sure Signs You've Already Had COVID.
Vitamin C
Adults should not take more than 2000 mg of vitamin C a day.
The good: "Vitamin C, or ascorbic acid (AA), is first and foremost an electron donor," says Bogdan Popa, MD. "This means it can directly donate electrons to function as an antioxidant. Functioning as an antioxidant allows it to neutralize harmful free radicals and act as a cofactor, also donating electrons to enzymes containing iron or copper. This donation is a critical step in keeping these enzymes 'active.' Enzymes that use vitamin C as a cofactor have widespread influence on our energy levels, structural integrity, and DNA. They are involved in maintaining methylation/demethylation balance (or turning on gene expression), making collagen, and furnishing L-carnitine and norepinephrine." There is also fascinating research about the impact of vitamin C and fasting in treating some cancers.
The bad: "Taking too much vitamin C can cause diarrhea, nausea, and stomach cramps," says the NIH. "In people with a condition called hemochromatosis, which causes the body to store too much iron, high doses of vitamin C could worsen iron overload and damage body tissues. Vitamin C dietary supplements might interact with cancer treatments, such as chemotherapy and radiation therapy. It is not clear whether vitamin C might have the unwanted effect of protecting tumor cells from cancer treatments or whether it might help protect normal tissues from getting damaged.
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