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Are you getting all the vitamins and minerals you need? When you ponder this question, your mind will immediately turn to your diet. Vitamin D is an exception. Though this vitamin can indeed be found in certain foods, its most important source is sunlight. Not everyone can harvest enough vitamin D from the sun, and some groups of people are advised to take a daily supplement to protect their health.
What is vitamin D, what do we need it for, and should you be taking a supplement or increasing your exposure to sunlight?
What Is Vitamin D?
Vitamin D is a vitamin, but not an essential dietary one. Though vitamin D can naturally be found — in relatively small quantities — in some foods, and though it is artificially added to many other foods, sunlight is the main source of vitamin D for humans. A healthy and balanced diet will provide people with most vitamins and minerals they need in sufficient amounts, but vitamin D is a different story. The simple fact that vitamin D is widely available through sunlight doesn't mean that everyone gets enough through spending time outside, either.
Food sources of vitamin D can be divided into three groups: meat sources of vitamin D (D3 or cholecalciferol), plant sources of vitamin D (D2 or ergocalciferol), and foods that are artificially fortified with vitamin D.
Sources of vitamin D3 include various kinds of fish (like salmon, mackerel, sardines and herring), cod liver oil, oysters, caviar, salami, ham, liver and sausages. Eggs are a good source of vitamin D3 for lacto-ovo vegetarians. Cereals, milk, yogurt and orange juice are often fortified with vitamin D3.
Natural sources of vitamin D2 include shiitake and portobello mushrooms and alfafa.Like vitamin D3, vitamin D2 is also produced synthetically. Research suggests that vitamin D3 is much more beneficial than vitamin D2, however, because it is more easily absorbed by the body.
Both types of supplements have about the same cost, so vitamin D3 is a better choice unless you are a strict vegan. Jews who keep kosher can take vitamin D3 supplements but need to look out for a hechsher. Halal vitamin D supplements are also available for Muslims.
Why Do We Need Vitamin D?
We need vitamin D for lots of different things, and research about its role in the human body is always ongoing but sometimes controversial and though it is recommended for a variety of diseases, adequate scientific evidence to support the effectiveness of supplements is often lacking.
Here's what we know at the moment. Humans need vitamin D for strong bones and teeth throughout life, even before birth.
Vitamin D is, in combination with sufficient amounts of calcium, important for the prevention of osteoporosis or brittle bones. Children up to four years old need vitamin D to prevent rickets, a bone condition caused by a vitamin D deficiency.
A lack of vitamin D can cause low muscle tone in people of all ages, and recent research further suggests that higher vitamin D levels in mothers during pregnancy lead to a better muscle tone in babies. A child's grip is stronger if his mother's vitamin D levels were sufficient while he was in utero. It should come as no surprise that vitamin D is prescribed to people with muscle weakness, then.
Now for the controversial bit. Vitamin D may also be used by people with a variety of other ailments and conditions, and may or may not be beneficial for them. Conditions for which vitamin D is sometimes taken include bone conditions, cardiovascular diseases, multiple sclerosis, rheumatoid arthritis, lung diseases, and even premenstrual syndrome (PMS).
Finally, you might be advised to take vitamin D if you have skin conditions such as vitiligo, scleroderma, or psoriasis, if you have a weak immune system for a range of reasons, or if you are deficient in phosphorous or calcium. In that case, boosting your vitamin D levels will aid the absorption of these minerals.