The term “vitamin D” is a bit misleading, because it isn’t actually a vitamin at all. Vitamin D is a hormone that is synthesized by the body for a variety of functions. One of these is to help the body absorb calcium for strong bones, which is why so many calcium supplements also include vitamin D. Adequate vitamin D stores can help to prevent osteoporosis in adults and rickets in children. It ensures proper brain development and bolsters immune function. It may also provide protection from high blood pressure, some cancers, and other autoimmune conditions.
AM I GETTING ENOUGH?
Vitamin D is not plentiful in the food supply.* Unlike other vitamins, however, the body can manufacture vitamin D when exposed to natural sunlight. Just 15 minutes each day in adequate sunshine is sufficient for maintaining a healthy level and there is no risk of overdose because the body will only make as much vitamin D as is needed. In many locations, however, there is not sufficient sunlight year-round to ensure adequate vitamin D. For anyone living north of the line between San Francisco and Baltimore, it is impossible to rely on the sun for vitamin D during 6 months of the year. Even south of that line, many people do not spend sufficient time outdoors with enough skin exposed to synthesize the amount of vitamin D they need.
Vitamin D is not plentiful in the food supply.* Unlike other vitamins, however, the body can manufacture vitamin D when exposed to natural sunlight. Just 15 minutes each day in adequate sunshine is sufficient for maintaining a healthy level and there is no risk of overdose because the body will only make as much vitamin D as is needed. In many locations, however, there is not sufficient sunlight year-round to ensure adequate vitamin D. For anyone living north of the line between San Francisco and Baltimore, it is impossible to rely on the sun for vitamin D during 6 months of the year. Even south of that line, many people do not spend sufficient time outdoors with enough skin exposed to synthesize the amount of vitamin D they need.
At higher risk for deficiency are people with darker skin tone, the elderly, obese persons, and anyone with a fat absorption condition such as cystic fibrosis or irritable bowel disease. While wearing sunscreen is recommended for preventing skin cancer and wrinkles, it prevents vitamin D absorption. Those who wear sunscreen regularly are also at higher risk for deficiency.
SIGNS OF DEFICIENCY
The signs of a mild vitamin D deficiency are ambiguous. Most Americans are unaware that they have inadequate vitamin D stores. They may experience increased risk of fracture, muscle weakness, fatigue, or low mood. The best way to determine if you are vitamin D deficient is with a simple blood test.
SUPPLEMENTATION
If you have low bone density or muscle weakness resulting from a vitamin D deficiency, add regular physical exercise to your daily routine, along with any supplementation. This should include some form of weight bearing activity to build bone and muscle, such as walking/jogging, lifting weights or yoga.
*Note: Some people aim to increase vitamin D by consuming “vitamin D milk.” This is another term for “whole milk” which is very high in saturated fat and cholesterol. Whole milk does not contain more vitamin D than fat-free (skim) milk. All milk and milk substitutes (soy, rice, almond, etc.) are fortified with vitamin D. It is not nutritionally advised, however, to consume enough of these products to supply the full daily requirement of vitamin D.
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