Regardless of where you live—in a hot, sunny climate or further north—it’s quite possible that you aren’t getting enough of the sunshine vitamin. It’s estimated that 80 percent of Americans are deficient in vitamin D. To test your knowledge of this essential nutrient, take our quiz.
1. The safe upper limit for daily amounts of vitamin D supplements is:
a) 1,000 IU
b) 2,000 IU
c) 3,000 IU
d) 4,000 IU
e) 5,000 IU
2. Which of these fish contains the most vitamin D in a typical serving?
a) Sardines (2, canned)
b) Tuna (3 oz., canned)
c) Sockeye salmon (3 oz.)
3. Vitamin D supplements are best absorbed when taken with food that contains:
4. Vitamin D is necessary for the absorption of which mineral?
5. Sunscreen blocks UV rays if the SPF is high enough. How high does it need to be?
a) SPF 8
b) SPF 15
c) SPF 20
d) SPF 30
6. It’s possible to produce vitamin D if sun is shining on you through a window.
7. It’s impossible to get enough vitamin D from the sun in northern climates.
8. Which of these conditions can be relieved or improved with adequate vitamin D?
a) High blood pressure
b) Diabetes risk
c) Chronic pain
d) High blood pressure and diabetes risk
e) All of the above
9. If you don’t get a sunburn or tan, you aren’t getting enough sun to make vitamin D.
The dminder app can estimate how much vitamin D you’re getting from food and sun exposure, and uses your phone’s GPS to calculate your optimum sun time anywhere in the world. Get it from app stores or check it out at dminder.ontometrics.com.
1. d) The Institute of Medicine, at the National Academy of Sciences, recommends an upper limit of 4,000 IU daily, but some deficient individuals may need more, based on blood tests. Nutritionally oriented health practitioners often recommend taking 1,000–2,000 IU daily.
2. c) Salmon contains 447 IU, tuna contains
154 IU, and sardines contain 46 IU.
3. b) Fatty food increases absorption.
4. c) Calcium. Without sufficient vitamin D, bones can become brittle, thin, or misshapen.
5. a) UV rays are blocked with SPF 8 or higher sunscreen, if it is applied properly and often enough.
6. b) UVB rays, which produce vitamin D, do not penetrate glass.
7. b) With enough sun exposure during spring, summer, and fall, it’s possible to produce enough vitamin D for the whole year, because the vitamin is stored in the liver and fat. This is true even in far-north climates. However, most people don’t get enough sun exposure to meet their vitamin D requirements.
8. e) Adequate vitamin D can reduce high blood pressure, reduce risk of diabetes, and provide some relief from chronic pain. It can also reduce risk for heart disease, osteoporosis, rheumatoid arthritis, and some cancers.
9. b) To make vitamin D from sun exposure, it isn’t necessary to stay out long enough to get a burn or tan.