There was a recently published study focusing on the low levels of vitamin D in children. Researchers focused heavily on the fact that children need to be getting more vitamin D, citing the host of potential health problems that can arise from insufficient intake of this vitamin. A shocking 70% of children were characterized as being either deficient or insufficient in vitamin D. What’s been glossed over in this study though, is that vitamin D levels have been declining across the general U.S. population for the last 20 years. The question becomes, should you be worried about vitamin D levels, and if so, how best to increase vitamin D levels?
Why Worry About Vitamin D Levels?
Vitamin D is a fat soluble vitamin that exists in a variety of forms within the body. The primary “pre-vitamins” are D2 and D3. Vitamin D2 comes primarily from plant sources, while vitamin D3 is found in animals. These two are known collectively as calciferol. The active form of vitamin D (also known as calcitriol) is synthesized from these two “pre-vitamins” in the liver and kidneys. Altogether, these compounds function more as hormones than classic vitamins, and are known to be responsible for regulating the absorption of calcium and phosphorus from the small intestine. It has been known for some time that vitamin D is responsible for calcium absorption. But recent research on the subject of vitamin D has shown it may inhibit tumor growth, reduce the risk of dementia, and may even help prevent the common cold. There is a renewed interest in the scientific community toward this vitamin, for reducing the risk of a variety of immune and respiratory ailments, in addition to its classically known function at preventing rickets and osteoporosis.
How To Increase Vitamin D Levels
Sunlight To Increase Vitamin D Levels
Most of us know that sunlight enhances vitamin D production in the body. What’s less commonly understood is that all biological synthesis of vitamin D starts from a form of cholesterol, and requires exposure to UV light. Vitamin D3 (generally considered the more active pre-vitamin) is produced in the dermis, and later converted to calcitriol. Short wavelength light (UV-B) produces free radicals, which is responsible for the synthesis of pre-vitamin D3. Unfortunately, the wavelengths of light responsible for this conversion are the same ones filtered out by a good sunblock, melanin, and clothing. Conventional wisdom suggests that most people only need 10-20 continuous minutes of daily sunlight exposure to produce adequate amounts of vitamin D. However, more recent research suggests that as people (and kids) spend less time outdoors, it becomes difficult to attain that minimum threshhold for adequate production. This fact, coupled with lifestyle changes (such as the liberal use of good sunblock) and environmental conditions (smog, etc.) make it progressively more difficult to produce adequate amounts of vitamin D. Factor in the fact that UV-B exposure varies seasonally, with northern locales having less exposure, and the body’s production of adequate amounts of vitamin D seems less apparent.
The importance of locale in the production of vitamin D can be found in the following statement by Boston University researcher Michael Holick:
“…supplements are often the only option in winter: “If you live above Atlanta, Ga., you basically cannot make any vitamin D from November through February; for New York and Boston, it’s mid-October through mid-March.”
What Is An Appropriate Level of Vitamin D?
According to the Harvard School of Public Health, a fair skinned person can produce 15,000 International Units (IU) of daily vitamin D with just 30 minutes of optimal UV-B exposure. The extent of the problem becomes more apparent when you consider that the recommended Adequate Intake of vitamin D for people under the age of 50 is currently fixed at 200 IU (a mere 5 micrograms) per day. However, the growing body of evidence in favor of vitamin D recommended health benefits has prompted some experts to suggest drastically higher levels. With that in mind, it should be noted that the currently cited AI levels vary by age, as follows:
Under 50 years of age: 200 IU (5 micrograms)
Age 51-70: 400 IU (10 micrograms)
Age 71+: 600 IU (15 micrograms)
Dietary guidelines for Americans come up for review by the National Institute for Health in 2010. Many experts are expecting those recommendations to increase substantially, perhaps to as much as 1000 IU per day.
Foods To Increase Vitamin D Levels
A quick review of NutritionData.com shows that with just a few exceptions, the top sources of vitamin D products are almost exclusively coldwater fish and oysters. The exceptions are catfish, and soy-milks, and vitamin D supplements for infants. The leading source of vitamin D on their list is cod liver oil at 1350 IU per tablespoon. Good luck getting your kids to drink THAT. Some other sources of vitamin D include:
- Catfish (3 oz): 425 IU
- Salmon (3.5 oz): 360 IU
- Sardines (1.75 oz): 250 IU (canned in oil, drained)
- Tuna (3 oz): 200 IU (canned in oil)
- 1% Milk (1 cup): 127 IU (usually vitamin D2)
- Kellogg’s All-Bran Cereal (with extra fiber, 1/2 cup): 54.6 IU
- 1 cup white stir-fried mushrooms: 22.5 IU (see mushroom nutrition)
- 1 whole egg (vitamin D is in the yolk): 20 IU
What becomes painfully apparent is that for the majority of the U.S. population to reliably achieve even the currently recommended adequate intake of 200 IU per day (year-round) would require consuming about 2 cups of vitamin D fortified milk every day. Trying to achieve levels as high as 1000 IU reliably requires either cod liver oil or a supplement. If you decide to pursue the supplement route, be judicious in your selection. Most multivitamin supplements contain 400 IU of pre-vitamin D2, which is considered by experts to be the less active form. Furthermore, attempts to increase this level by taking more supplements may lead to dangerously high levels of vitamin A.
Do any of you remember being a kid and your grandparents keeping cod liver oil in the refrigerator? I guess we still have things to learn from our grandparents. I remember thinking that was kind of gross. Shows what I know… Guess its true that we turn into our parents, and then our grandparents too. While I can’t do straight cod liver oil, you can buy an orange-flavored emulsified oil that is tolerable, and will give the benefits of omega fats as well. If you can’t stomach fish oils, though (my wife can’t), then go for the tablets.