How to Get Your Daily Dose of Vitamin D
Important Reasons to Soak Up the Sunshine Vitamin
-- By Becky Hand, Licensed & Registered Dietitian
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Why Vitamin D Matters
Vitamin D is best known for its role in bone health; it helps your intestines more efficiently absorb the bone-building minerals calcium and phosphorous that you get from food. Vitamin D then helps to deposit these minerals in your skeleton and teeth, making them stronger and healthier. Therefore, vitamin D helps prevent the fractures associated with osteoporosis, the bone deformation of rickets, and the muscle weakness and bone aches and pains of osteomalacia (the softening of bones).
But a deficiency of vitamin D goes beyond bones—it can cause numerous health problems. Because it's a hormone, and your body is full of receptors for this hormone, it plays a role in the prevention of many ailments. A lack of vitamin D may lead to:
- Cancer. Emerging research suggests that vitamin D has an anti-cancer benefit. It may stop the growth and progression of cancer cells and be beneficial during cancer treatment, too. Vitamin D is most strongly associated with colon and prostrate cancers, but it may also protect against breast, lung, ovarian, stomach, bladder, esophageal, and kidney cancers.
- Hormonal problems. Vitamin D influences the functions of insulin, rennin, serotonin and estrogen—hormones involved with health conditions such as diabetes, blood pressure, heart disease, stroke, depression and premenstrual syndrome.
- Obesity. Some research shows that a vitamin D deficiency can interfere with the "fullness" hormone leptin, which signals the brain that you are full and should stop eating.
- Inflammation. Vitamin D helps control the inflammation involved with periodontal disease, rheumatoid arthritis and osteoarthritis.
- Weakened immune system. Vitamin D plays a role in a strengthening your immune system, especially in autoimmune disorders (when the body attacks itself) like multiple sclerosis and rheumatoid arthritis.
The current Dietary Reference Intake (DRI) for adults, as set by the Institute of Medicine, varies by age:
- Ages 19-50: 200 IU (International Units) daily
- Ages 51-70: 400 IU daily
- Ages 71 and older: 600 IU daily
Are you deficient on D?
Because vitamin D is a fat-soluble vitamin, the body can store it for long periods. Tracking your intake from foods or supplements alone won't determine if you're truly deficient in vitamin D. Moreover, even if you appear to get enough vitamin D from foods or supplements, there is no guarantee that your body is absorbing or using all the D that you appear to be consuming. The only way to know your vitamin D status is to ask your health care provider for a vitamin D test. (It is best to have the test preformed about a month before the beginning of winter.) Your doctor will check your blood level of 25-hydroxyvitamin D. A desirable result for this test is 30 ng/ml (nanograms/milliliter) or higher. A reading of 20-29 is considered insufficient, and less than 20 ng/ml is deficient.
The ABC's of Getting Your D
Whether deficient or not, vitamin D is a key nutrient for everyone. There are three possible ways to get it: from the sun, food or supplements. Here's the lowdown on all three.
Sunlight is an excellent source of vitamin D. It is free and abundant. The ultraviolet B (UVB) rays from the sun convert a precursor into vitamin D, which becomes 25-hydroxyvitamin D in the liver and is then activated to 1, 25-hydroxyvitamin D in the kidneys. A person sitting outside in a bathing suit in New York City gets more vitamin D in 20 minutes than from drinking 200 glasses of milk. In fact, many experts suggest getting 10 minutes of unprotected sun on the arms and face or arms and legs, three times weekly and before applying sunscreen. But getting vitamin D from the sun isn't that simple. UVB rays vary greatly depending on latitude, cloud cover, time of year and time of day. Above 42 degrees north latitude, the sun’s rays do not provide sufficient D from November through February, for example. Remember too, that UVB rays do not penetrate glass or sunscreen with a sun protection factor (SPF) of 8 or more. The elderly and people with darker skin also produce less vitamin D. Talk to your health care provider about unprotected sun exposure; not everyone in the scientific community thinks that even a little sun is a good idea, because of the risk of skin cancer.
Food can provide vitamin D, but it's difficult to get 1,000 IU of vitamin D from your diet alone. Only a few foods (fatty fish, liver and egg yolks) contain vitamin D naturally. Other foods, such as milk and cereal, are fortified with vitamin D.
| Food Source | Vitamin D (IU) |
| Cod liver oil+, 1 tablespoon | 1,360 |
| Salmon, 3.5 oz cooked | 360 |
| Mackerel, 3.5 oz cooked | 345 |
| Sardines, 1.75 oz canned in oil | 250 |
| Tuna fish, 3 oz canned in oil | 200 |
| Milk, 1 cup (fortified*) | 100 |
| Orange juice, 1 cup (fortified) | 100 |
| Soymilk, 1 cup (fortified) | 100 |
| Yogurt, 6 oz (fortified) | 60-80 |
| Pudding, 1/2 cup (made with fortified milk) | 50 |
| Ready-to-eat cereal, 3/4 cup to 1 cup (fortified) | 40 |
| Egg, 1 whole (vitamin D found in yolk) | 20 |
| Margarine, 1 teaspoon (fortified) | 20 |
| Beef liver, 3.5 oz cooked | 15 |
| Swiss cheese, 1 oz | 12 |
*Check food labels; not all products are fortified with vitamin D and amount per serving varies by brand.
+Before trying the potent supplement cod liver oil (or any fish oil), check with your doctor because of fish oil's vitamin A content and possible toxicity.
Supplements may also be necessary. A multivitamin-mineral supplement typically contains 400 IU of vitamin D. Many supplements contain ergocalciferol, called D2, which is a less potent form of vitamin D derived from the irradiation of yeast; it's also less expensive. You are better off using a supplement that contains cholecalciferol, or D3, made from fish oil, the fat of lamb’s wool (lanolin) or the chemical conversion of cholesterol. This form is much better absorbed by the body, but it can be harder to find and more expensive. (Check the supplement label or inquire with supplement manufacturers to find out whether they use D2 or D3 if the label doesn't specify.) Vitamin D is often added to calcium supplements, or you can also buy a vitamin D supplement by itself. Vitamin D is a fat-soluble vitamin, so take your supplement with a meal containing some fat to enhance absorption.
Spark Action!
It is far too early to call vitamin D a wonder drug, but evidence of its importance is mounting. Therefore, you may want to consider this Spark of advice:
- Aim to get 800-1,000 IU of vitamin D daily.
- Talk to your health care provider about the need for a vitamin D test, and discuss your test results.
- Talk to your health care provider about careful sun exposure—10 minutes on the arms, face, and/or legs, three times weekly—before you slather on the sunscreen.
- Talk to your health care provider about a vitamin D supplement or a multivitamin-mineral supplement that contains vitamin D. If you take one, make sure it is the vitamin D3 form, cholecalciferol.
- Eat foods rich in vitamin D each day.
- Maintain a healthy weight.
- Talk to your doctor if you are using the weight loss drug, Orlistat (brand names include Xenical and Alli). This drug may decrease the absorption of vitamin D.
- Antacids, some cholesterol lowering drugs, some anti-seizure medications, and steroids (like Prednisone) interfere with the absorption of Vitamin D, so discuss your vitamin D intake with your doctor or pharmacist if you take any of these drugs.
