Vitamin D is a vital part of our bone health, but how much is too much?

Published: September 12, 2022 | Updated: June 25, 2024

You know vitamins are good for you, and you might know humans get vitamin D from exposure to the sun’s warming rays. There are also vitamin D supplements sold over the counter. Can you overdose on vitamin D? How much vitamin D do you need?

What is vitamin D for?

“Vitamin D is an antioxidant and anti-inflammatory. It protects the brain cells and supports immune health. Vitamin D also regulates calcium and phosphate in the body,” said M. Nancy Fuller, APRN, nurse practitioner with Norton Community Medical Associates. “Anything that works on calcium is going to affect your bones, but the body only absorbs calcium when there is vitamin D present.”

How do you get vitamin D?

This essential nutrient is in some foods such as fatty fish (salmon, mackerel, etc.), and fortified milk and cereal.

“Your body makes some vitamin D when the skin is exposed to direct sunlight. A chemical in the skin converts sunlight to active vitamin D so it can be used,” Nancy said.

Children typically don’t have low levels of vitamin D, since they spend more time outdoors than adults. Since research has shown that prolonged exposure to the sun can damage DNA in the cells, cause skin cancer and prematurely age skin, adults shouldn’t stop taking precautions.

“Don’t skimp on the sunscreen or go without a hat to get more vitamin D,” Nancy said. “The benefits of protecting the skin from sun damage far outweigh any negatives, and you still can maintain healthy vitamin D levels without abusing your skin.”

Besides the sun and some foods, the best way to boost vitamin D is with supplements.

“Vitamin D is sold over the counter, meaning you don’t need a prescription,” Nancy said. “Adults ages 18 and older will need anywhere between 15 and 20 micrograms a day. It depends on your gender, pregnancy status and age.”

How can I tell if I have vitamin D deficiency?

Lack of vitamin D can lead to bone-related conditions such as softening of the bones (osteomalacia), weak or brittle bones (osteoporosis) and an increased risk for breaks. 

“A simple blood test will tell your doctor if you need a boost in vitamin D,” Nancy said. “Vitamin D is measured in nanograms per milliliter (ng/mL). We recommend between 20 and 50 ng/mL, roughly. Again, it depends on several factors. Your doctor can help you determine what is a good level for you.”