The ABCs of Vitamin D
From the NHLBI website; recommended by
Heidi Beer and Cindy Salmon,
WIN for Alaska, Inc. Wellness Consultants
What is vitamin D and where do we get it?
Vitamin D is a fat-soluble vitamin found in some foods which is made in your body after exposure to ultraviolet rays from the sun. The summer months are the best time to benefit from the sun’s rays in making vitamin D. You only need about 15 minutes of sun exposure several times a week. The following foods are good sources of vitamin D:
• 3.5 oz of salmon (360 IU)
• 3.75 oz of sardines (500 IU)
• 5 oz of canned tuna (235 IU)
• 1 cup milk (100 IU)
• Vitamin D fortified orange juice (100 IU)
• 1 cup soy milk (100 IU)
Why is vitamin D important?
Vitamin D helps the body maintain normal blood levels of calcium and phosphorus. It also promotes calcium absorption into our bones, which helps to form and strengthen bones and regulate blood pressure and heart rhythm. Therefore, it helps prevent the softening of bone, a condition called rickets in children or osteomalacia in adults. Low levels of vitamin D may contribute to developing certain types of cancer, such as colon, breast, and prostate cancers.
Low levels may also contribute to heart disease and diabetes.
Who's at risk for a vitamin D deficiency?
• Older adults: The skin of adults aged 50 and older does not synthesize vitamin D efficiently and the kidney is less able to convert vitamin D to its active hormone form.
• People with darker skin color: The melanin content is higher in people with darker skin which reduces the skin's ability to produce vitamin D from sunlight.
• People with fat malabsorption: Because vitamin D is a fat-soluble vitamin, people with a reduced ability to absorb dietary fat, such as those with Crohn's disease, cystic fibrosis, celiac disease or liver disease, or those who have had part or all of their stomach or intestines removed (as a result of gastric bypass surgery, for example), may not adequately absorb vitamin D.
• People with limited sun exposure: Homebound individuals, people living in northern latitudes like New England and Alaska, and those who wear protective clothing are at risk for vitamin D deficiency. (Alaskan sunshine is only strong enough from May to October to produce vitamin D in the body.)
How much do we need?
The recommendations are in question. Many experts advise those from 1-50 years of age to get 2000 IU (50 ug) a day. This is the current tolerable upper intake level–the safest maximum amount. It is 10 times more than the current minimum amount. If you want to know your level, ask your health care provider to test the vitamin D in your blood.
How much is too much?
Ingesting more than 2000 IU (50 ug) a day of vitamin D is too much for most people. Vitamin D toxicity raises blood calcium levels, which can calcify soft tissues, create kidney stones, and abnormal heart rhythms. Other symptoms are mental confusion, nausea, vomiting, poor appetite, weight loss, constipation, and weakness. If you have pre-existing kidney problems, ask your provider how much vitamin D is right for you in the winter.
What about a supplement?
It's difficult to get your daily recommended amount just from foods containing vitamin D, and most multivitamins contain only 400 IU of vitamin D. If you need an additional vitamin D supplement, look for vitamin D3 (cholecalciferol) and the USP (U.S. Pharmacopeia) Logo. Products with the USP logo have been verified for:
1. Contents
2. No harmful contaminant levels
3. Ability to dissolve and release in the body
4. Good manufacturing practices
Sources: National Institutes of Health Office of Dietary Supplements. Dietary Supplement Fact Sheet: Vit D.; D Vitamin. (2008).; Lawrence, Jeremy. The Virtues of Vitamin D. (2007).; “Position of the American Dietetic Association and Dietitians of Canada: Vegetarians diet,” Journal of the American Dietetic Association 106:7 (2006).; Agency for Healthcare Research and Quality. (2007). Effectiveness and Safety of Vitamin D in Relation to Bone Health. |
WIN for Alaska, Inc.