How Much Vitamin D Do You Really Need?

Vitamin D plays a role in the inner workings of nearly every system in our bodies. As a result, supplementing with vitamin D has become common practice. But is it necessary?

April 8, 2016
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In recent decades, an emphasis on sun damage has led many of us to avoid the sun. But the other side of this coin is that without the sun you can become deficient in vitamin D, a nutrient that’s crucial to optimal health. In fact, vitamin D plays a role in the inner workings of nearly every system in our bodies. As a result, supplementing with vitamin D has become a common practice. But is it necessary? Let’s take a closer look at this critical nutrient.

What’s Vitamin D?

Unlike many other vitamins, the body can make its own vitamin D when it’s exposed to the sun. This is not true of vitamins such as A and C, which the body cannot make and therefore need to be obtained through diet. Once the body makes vitamin D it converts it to a hormone called calcitriol, which is important to many of the body’s systems. For example, vitamin D is critical to strong bones because it helps with the absorption of calcium and phosphorus. In fact, even if you get ample calcium from the foods you eat, without vitamin D, the body cannot properly absorb these minerals.

To a large degree, there’s a lot we don’t know about how vitamin D works in the body, but we do know that it’s found in nearly every cell and that it’s important for the optimal function of the muscles, heart, and lungs, as well as having important anti-cancer benefits. Research has shown that those who are deficient are at an increased risk of having a heart attack. Vitamin D has also been shown to help the body fight off infection.

How Much Vitamin D Do You Need?

The National Institutes of Health and the Health and Medicine Division of the National Academies of Science both currently state that number is around 600 international units (IU) for the majority of adults. It’s the same for pregnant and breastfeeding women. Infants from birth to one year only need 400 IU, and seniors age 71 and older need 800 IU. This is largely due to the fact that the elderly are at an increased risk of osteoporosis. Recent scientific evidence has shown that this number may be statistically flawed, however, because the recommendations were based on averages that were far too low and that the daily allowance may actually be more like 8,000 IUs. This is a wide range, so it’s best to get your blood tested and establish with your doctor what your safe levels should be.

How to Get Enough Vitamin D From the Sun

It’s difficult to quantify how much sun each individual needs to avoid a vitamin D deficiency because your skin’s pigment plays an important role. Sun strength is also important, based on the time of day. For example, if you’re fair skinned, being outside at noon for just a few minutes per day may be plenty. Experts say that for a fair-skinned individual, going out in the sun for just 10 minutes when the sun is strong can produce 10,000 IU of vitamin D, which can last you through cloudy and rainy days. Going beyond that time may be too much sun. But if you have a darker skin tone it may take around 15 minutes or more.

Can You Get Vitamin D From Foods?

It’s difficult to get enough vitamin D from your diet because it’s not found in very many sources. But there are a few foods that contain ample amounts. Fatty fish like mackerel and salmon contain between 400 and 600 IU, whereas eggs yolks and beef liver contain around 40 IU. Canned fish like tuna and sardines contain around 140 IU, and fortified foods like milk, almond milk, yogurt, orange juice, tofu, cereals, and oatmeal contain between 100 and 200 IU.

Can You Overdo Vitamin D?

Yes you can. Some doctors fear that too many people are over supplementing, taking in excessive amounts of the vitamin (another reason why you need to get tested). Too much vitamin D can cause overly high blood calcium levels, which lead to nausea, constipation, and even kidney stones.

The bottom line is that you can have too much of a good thing. Although there’s differing evidence when it comes to how much is too much, getting the vitamin through supplementation does put you at risk of overdoing it. If you are supplementing, talk to your doctor about how much you really need.

Vitamin D is an important nutrient for the optimal function of the body’s systems. But a little sunshine combined with a diet rich in fatty fish, eggs, milk, and tofu may be all you really need.

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