The Neglected Nutrient Part 2: Vitamin D for Bones

Vital Choices newsletters in June 2005 contained a series of information-packed articles on the scientific research connection sunlight, vitamin D and human health.  Bone health in relation to vitamin D and sunlight is the focus of the second article.

 

The Neglected Nutrient Part 2: Vitamin D for Bones
Baby boomers face fractured futures, absent adequate “D” 
by Craig Weatherby 

 

Q:  What do 19th century London-dwellers and conservative Muslim women living in 21st century Scandinavia have in common?  

A:  Both display a tendency toward vitamin D deficiency.

Historical accounts indicate that rickets was common in 19thcentury English cities, probably because coal smoke was so thick it hid the vitamin D-producing midday sun. (Rickets is a disease in which developing bones soften and curve because they aren’t receiving enough calcium, uptake of which into bones requires adequate vitamin D.)

Modern research suggests that the traditional head covering called the hijab leaves Islamic women living in already sun-lacking northern latitudes prone to substantial vitamin D deficiency, which can promote cancer, depression—and osteoporosis.

 

Vitamin D and bone health

You can’t build bone without calcium, and you can’t absorb and utilize calcium without vitamin D.  This is why vitamin d was first identified as an essential anti-rickets nutrient.  (Omega-3s are also associated with better bone health.)

People with severe osteoporosis often exhibit low body levels of vitamin D. Vitamin D deficiency is fairly common among the house- or institution-bound elderly, who often receive less sun exposure.  It is also common among seniors and adolescents in northern latitudes. Aside from osteoporosis, the consequences of this deficiency include increased risk of hypertension, and several common types of cancer.

 

Millions face fractured futures

An estimated 1.5 million Americans—mostly elderly—suffer an osteoporosis-related bone fracture every year. Almost half of Caucasian women (i.e., women of European extraction) age 50 or older will experience a hip, spine, or wrist fracture, while about 15 percent of Caucasian men will suffer a similar fate. While the lifetime risk for non-Caucasian women is less, it seems to be rising among Hispanic women.

Fractures can have catastrophic consequences. For example, the risk of death is three to four times greater than normal among hip fracture patients during the first three months after the fracture.  And fractures often initiate a downward spiral that devastates quality of life, with many victims becoming isolated and depressed. Spinal fractures, which are not diagnosed and treated as easily, can disfigure and cause chronic pain.

Osteoporosis is the most important underlying cause of fractures in the elderly.  Some 10 million Americans over age 50 have osteoporosis, while another 34 million suffer from low bone mass (osteopenia) of the hip, which puts them at risk for fractures and attendant complications.

 

Getting enough D?

According to a 2004 report by the U.S. Surgeon General, “Relatively few individuals follow the recommendations related to the amounts of physical activity, calcium, and vitamin D that are needed to maintain bone health.”

Dietary supplements are often inferior to food, in terms of the effectiveness of their vitamin D. Instead of the D-3 form used by the body, and found in fish, most mass market brands contain 400 IU of the D-2 form, which is biologically inefficient.   In other works, it takes much less D-3 to equal the health effects of a given amount of D-2.

The distinction between D-2 and D-3 is similar to the difference between the “short-chain” or plant-source omega-3 called ALA, only 5-15 percent of which the body can convert to the long-chain forms it needs (e.g., EPA and DHA), and “long chain” omega-3s which are found only in fish and fish oil supplements.  

In addition, many multivitamins also contain vitamin A, which interferes with the body’s ability to absorb vitamin D.

The evidence concerning the effects of combined calcium-vitamin D supplements on bone density and fracture risk is mixed.  One study found that among 295 men and women 65 years of age or older, taking 500 mg of calcium plus 700 IU of vitamin D3 per day reduced bone loss in the neck, spine, and total body moderately over a three-year period, and reduced the incidence of non-vertebral fractures.  (The U.S. RDA for people aged 51-70 or older is 400 IU.)

However, other studies, including two recent ones from the UK, indicated that calcium and vitamin D supplements had fairly little impact on risk of fractures in the elderly.  These mixed results suggest the possibility that, for unknown reasons, whole foods are better sources.

 

Department of strange but revealing studies

This is a summary of the Danish study we alluded to in our opening Q & A.

Sixty veiled Arab women and 44 age-matched Danish women were randomly selected amongst patients contacting a health care center for various reasons. Ten ethnic Danish Moslem women were included as controls.

Dietary intake of vitamin D and calcium were estimated through a historical food intake survey. 

The veiled Arab women consumed very little vitamin D (42 IU) compared with ethnic Danish Moslems (540 IU) and non-Moslem Danish control subjects (300 IU.  

The researchers concluded that the veiled Arab women suffered very limited sunlight exposure and woefully insufficient dietary vitamin D.

But, while dietary vitamin D intake among the veiled, ethnic-Danish Moslems was relatively high—probably from the Danish staple food herring—they were still vitamin D-deficient in terms of body levels of the nutrient.

The researchers concluded that the daily intake of vitamin D in sunlight-deprived people—such as veiled women—should be at least 1000 IU.

 

Source: http://www.imakenews.com/vitalchoiceseafood/e_article000411952.cfm?x=b53jlSr,b1WDbhNQ,w

164 views

Tags: vitamin d