Most vitamins are useless, but there's one you could probably use
Not exactly. While it may be enticing to reach for that vitamin-C packed drink when feeling under the weather, your body can't actually process it all. Plus, a balanced diet typically carries enough B, C, and E vitamins to keep your body running smoothly.
But there is one that may be worth taking in supplement form: Vitamin D.
Though how much of this vitamin the body is actually able to use is still up for debate, vitamin D is tricky to get simply from foods. In that case, a supplement can be helpful.
Why we need vitamin D
Technically two different vitamins - D2, which mainly comes from supplements and food and D3, which comes from the sun - the fat-soluble vitamin D works to help build up bone strength. It's also used by our muscles for movement and by our immune system to fight infections.
Vitamin D often pairs off with calcium, because it helps our bones absorb the mineral.
Studies have found that people who consistently took vitamin D supplements lived longer, on average, than those who did not take them. Other studies suggest vitamin D is also helpful in preventing osteoporosis, a condition in which bones become weak and brittle.
How to get it
The suggested daily dose of vitamin D for most healthy adults is 600 IU (the measurement tool for fat-soluble vitamins), of which a serving of milk has about 25% of the daily amount.
Just don't go too far. Vitamin D overuse is linked with symptoms like vomiting, constipation, weakness, and weight loss, and it's almost always because of overused supplements, not from getting too much sun (your body knows how to regulate how much Vitamin D it makes). But that's typically when you hit daily levels of 4,000 IU, or almost seven times the recommended daily amount.