Ask HE: How Much Vitamin D Do You Need?

All kinds of news reports are popping up saying we’re a vitamin-D deficient nation. Is this true? If so, what does it mean and what can we do about it?
All kinds of news reports are popping up saying we’re a vitamin-D deficient nation. Is this true? If so, what does it mean and what can we do about it?
Q: How much vitamin D do I really need and where can I get it?

A: It may difficult to meet your needs if you don’t eat certain foods. On the flip side, too much can be toxic.

As we discussed in our Nutrient to Know series, vitamin D is important for bone health (it allows for calcium to be absorbed). It’s critical for both children and adults to get enough of this nutrient to prevent the risk of bone diseases like rickets (in children) and osteoporosis (in adults). Vitamin D also helps protect against high blood pressure and certain forms of cancer. There's also some research to support that when deficiencies of this vitamin are corrected in athletes, muscle strength and endurance improve. This doesn’t mean that more is better, just that when deficiencies are resolved, benefits are seen.

The good news is your body makes some of its own vitamin D with exposure to sunlight. The bad news -- some people don’t spend enough time in the sun to make the vitamin D they need and it’s hard to come by in foods (especially if you don’t eat dairy). A blood test can determine if you’re meeting your needs. If you are falling short, a supplement may be helpful but be careful with the dosage – too much can cause nausea, vomiting, weakness and even heart arrhythmias due to too much calcium in the blood.

Food sources should be your first line of defense. Some naturally contain this vitamin while others are fortified (see list below).Vitamin D comes in two main forms. Vitamin “D2” is synthesized by plants and “D3” is the form humans produce when their skin is exposed to sunlight. You might find either listed on a food or supplement label.

Dietary Sources of Vitamin D

The daily recommendation for both children and adults is 400IU per day.

3-ounces cooked salmon = 795 IU (199%)
3-ounced canned tuna = 154 IU (40%)
1 cup of milk = 120 IU (30%)
1 cup of fortified orange juice = 100 IU (25%)
1 cup of fortified cereal = 40 IU (10%)
1 large egg = 20 IU (5%)

Bottom Line: You need vitamin D, but overdosing on supplements can have dangerous consequences. Try to get what you need with food. If you do have a deficiency, speak with your doctor or registered dietitian to establish a safe diet and supplement regimen.

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