Vitamin D


Vitamin D is frequently low in people that live in our area. There are many benefits to a normal level of Vit D. Feel free to contact me to test your blood level. The link below demonstrates the Vit D content of ssalmon. Please read the following articles to understand the importance of Vit D in your health.

The Neglected Nutrient, Part 1: Vitamin D vs. Cancer
Sunlight and fatty fish seen as stellar sources of overlooked anti-cancer nutrient
by Randy Hartnell and Craig Weatherby

Over the past several decades, preventive-nutrition researchers—and the news media—focused attention on the vitamins now believed to help protect heart health (C, E, folic acid, B6, and B12) and to possibly reduce cancer risks (B6, C and E).

More recently, vitamin D came to the fore in connection with the discovery of widespread vitamin D deficiency among older Americans and post-menopausal women. This is serious, since vitamin D deficiency raises the risk of osteoporosis and resulting hip fractures, which can be the first domino in a cascade of disabling, life-threatening, medical events.

The good news is that fatty fish—like salmon, sardines and tuna top the list of known vitamin D food sources. And I suspect that if tested, sablefish would also rank near the top of the list, since it even more healthful fat than most salmon does.

We’ll cover the topic of vitamin D and bone health in an upcoming issue, but today I’d like to share surprising information about vitamin D and cancer of which many—me included—have been unaware. It seems that Vitamin D is a very important anti-cancer nutrient, and that many Americans aren’t getting enough from the only sources: foods, supplements, and sun exposure.

Later in this article, we’ll relate the fruits of our conversations with a former NASA physicist—Dr. William Grant—who detoured from atmospheric chemical detection to put the surprising anti-cancer powers of sunlight-derived vitamin D on the map…literally.

Vitamin D essentials

These are the key facts about vitamin D and health:

Sun comes first. Sunlight is the single biggest vitamin D “source” among Americans, with dietary sources a distant second. While, hypothetically, you could get all the vitamin D you need from foods and supplements, the current expert consensus recommendation of 1000-2000 IU/day for optimal health would be hard to get from food alone. The body manufactures vitamin D when the skin is exposed to ultraviolet-B (UVB) radiation: the shorter wave kind thought of as “burning” rays, which are blocked by sunscreens. The ultraviolet-A (UVA) in sunlight—the type most closely associated with dangerous skin cancers—has longer wavelengths and penetrates much deeper into skin.

Bone/nerve health. Vitamin D is needed for dietary calcium to be absorbed from the digestive tract. When calcium levels fall, the body “steals” it from bones in order to keep nerves and muscles functioning properly. Unsurprisingly, the best-known signs of vitamin D deficiency are osteoporosis and, in extreme cases, the weak-bone disease called rickets. Leading vitamin D researcher Dr. William Grant joins many experts in recommending calcium-magnesium supplements containing vitamin D. (Surprisingly, two recent large, well-controlled British studies found that high doses of supplemental calcium and vitamin D (1000 mg and 800 IU respectively) did not, compared with a placebo, prevent fractures among more than 8,000 elderly women and those with previous osteoporosis-related fractures.)

Cancer. Vitamin D is now considered a key anti-cancer nutrient. (See “Why vitamin D curbs cancer,” below, for much more on this point.)

RDA is too low. The current US RDA (recommended daily allowance) for vitamin D* varies with age from 200 to 600 international units (IU). Most experts say that these levels are too low for any purpose other than preventing severe deficiencies. Renowned vitamin D researcher Dr. Michael Holick believes that the RDA level for all age groups should be closer to 1000 IU (25 micrograms). While a recent study found that it is probably safe for healthy adults to take as much as 4,000 IU (100 micrograms) per day, research performed at Harvard by Dr. Edward Giovannucci suggests that consuming 2000 IU or more per day may provide optimal protection against cancer.

Suboptimal intake is common. Vitamin D intake—in terms of the blood levels likely needed for optimal prevention of cancer, osteoporosis, diabetes, hypertension, and multiple sclerosis—is generally insufficient, despite fortification of milk with vitamin D. And, as we’ve said, vitamin D deficiency among post-menopausal women and all older Americans is common. Fortification of food with greater amounts of vitamin D cannot provide sufficient vitamin D to the elderly—who suffer the greatest deficiency—without exceeding official U.S. safety levels for children.

*The current RDA is 200 IU (5 micrograms) per day for all people up to age 50, and for pregnant or nursing women; 400 IU (10 micrograms) per day for adults 51 to 70; 600 IU (15 micrograms) per day for all people aged 70 or older. Several conferences have been held in the U.S. in recent years, with the aim of revising the guidelines upward to account for increased requirements for conditions and diseases other than osteoporosis (e.g., cancer, MS, diabetes).

Top food sources of vitamin D

The only dietary source of vitamin D ranked higher than sardines and salmon is cod liver oil, whose vitamin A blocks absorption of some of its very high vitamin D content (1,360 IU or 340 percent of the Daily Value).

The Daily Value for vitamin D is 400 IU (10 micrograms) for all adults, which is the same as the RDA for adults aged 51-70. (The “Daily Value” numbers for nutrients were developed by the Food and Drug Administration to indicate whether a food contains a relatively large or small amount of a specific nutrient. experts believe that 400 IU per day is not sufficient for adults (pregnant or nursing women should not exceed 200 IU per day).

International Units(IU) of vitamin D per serving
Percent Daily Value (400 IU)
Sardines in oil, drained, 3½ oz.

Salmon, cooked, 3½ oz.

Mackerel, cooked, 3½ oz.

Tuna fish in oil, 3 oz.

Milk (nonfat, reduced fat, or whole), vitamin D fortified, 1 cup

Egg, 1 whole (with yolk)

Liver, beef, cooked, 3½ oz.

Cheese, Swiss, 1 oz.

Source: National Institues of Health

Why vitamin D curbs cancer

The results of epidemiologic (population), clinical, and animal studies demonstrate that tumor growth is inversely correlated to vitamin D levels: that is, tumors grow slower and smaller when vitamin D levels are higher. As the authors of a recent review article said, “The active metabolite of vitamin D3 … has been recognized for over 2 decades as a modulator of cell proliferation and differentiation in many cell types, including breast cancer.”

As early as 1980, Cedric Garland published the first research on the links between vitamin D and cancer risk. In 1985, his team reported the results of a landmark 19-year study in which they compared rates of colorectal cancer and dietary vitamin D intake among 1,954 men. They found that the half of the population reporting the highest vitamin D intake (based on food intake surveys) had half the risk of developing colorectal cancer. In 1989 Dr. Garland published a study whose results support his earlier finding. Scientific interest in this topic is growing fast: a recent search of “vitamin D and cancer” at PubMed turned up more than 1,000 entries.

Professor Michael Holick, Ph.D., M.D. directs Boston University’s Vitamin D, Skin, and Bone Research Laboratory, and shares Dr. Grant’s concern that excessive sun avoidance could lead to a deficiency in the body’s production of vitamin D.

Dr. Holick put the issue this way in recent review articles:

“Vitamin D deficiency has been associated with increased risks of deadly cancers, cardiovascular disease, multiple sclerosis, rheumatoid arthritis, and type 1 diabetes mellitus. Although chronic excessive exposure to sunlight increases the risk of non-melanoma skin cancer, the avoidance of all direct sun exposure increases the risk of vitamin D deficiency, which can have serious consequences.

“Vitamin D deficiency is an unrecognized epidemic in most adults who are not exposed to adequate sunlight. Sensible sun exposure (usually 5-10 min of exposure of the arms and legs or the hands, arms, and face, 2 or 3 times per week) and increased dietary and supplemental vitamin D intakes are reasonable approaches to guarantee vitamin D sufficiency.”

While they remain controversial in the cancer research community, Dr. Grant’s conclusions are supported by a great deal of prior research, and by the results of three subsequent studies by a British research team. As the UK scientists said, “Recent studies have suggested that exposure to ultraviolet (UV) radiation may be protective to some internal cancers including that in the prostate. The data confirmed that higher levels of cumulative exposure, adult sunbathing, childhood sunburning and regular holidays in hot climates were each independently and significantly associated with a reduced risk of this cancer.”

The connection between vitamin D and cancer is further bolstered by these key findings:

Vitamin D inhibits inappropriate cell division (as occurs in cancer) and enhances the anti-cancer actions of immune system chemicals (e.g., tumor necrosis factor, interleukins 1 and 6) and chemotherapy drugs (e.g., doxorubicin). It also reduces blood vessel formation around tumors and inhibits metastasis, both of which are important in fighting cancer once it develops.

The active hormonal version of Vitamin D is produced from circulating vitamin D by cells in organs prone to cancer (e.g., colon, breast, prostate, and skin), which means that it is able to influence the initiation and growth of cancers in these organs.

In light of this information, it certainly makes sense to pay more attention to your vitamin D intake. It’s gratifying to know that a single serving of our salmon, sardines, sablefish, or tuna can gets you a long way toward meeting the minimum requirements. (We’re in the process of testing each of them for vitamin D content, and will share those results when they come in.)

NASA scientist finds new, sun-centered, cancer-prevention paradigm

Last year, while attending a nutritional health conference I was surprised to hear a popular nutrition-oriented physician—Julian Whitaker, M.D.—tell the audience that the occasional sunburn likely presents less cancer risk than would the functional vitamin D deficiency resulting from excessive sun avoidance.

Coincidentally, I met and spoke at length to a leading vitamin D researcher, William B. Grant, Ph.D., at the same conference. Dr. Grant holds a doctorate in physics from UC Berkeley, and for most of his career he was a senior researcher for NASA, specializing in optical and laser remote sensing of the atmosphere.

However, during the 1990’s, Dr. Grant turned his attention to human health: a role that became public in 1997 with publication of the very first peer-reviewed scientific paper examining the links between diet and Alzheimer’s disease (AD). He identified total energy (calories) and total fat as the important AD risk factors, and found that fish and grain foods are the important AD risk-reduction factors. Fish oil appears to reduce the risk of Alzheimer’s in two ways: its omega-3 DHA is essential to proper brain-cell function, and its omega-3 EPA reduces inflammation. (Oxidative stress appears to promote AD, and reducing inflammation reduces oxidative stress.) His findings regarding fish oil and Alzheimer’s were later confirmed by at least two other studies.

Dr. Grant followed this work with research into the nutritional aspects of heart disease, arthritis, and cancer, and in 2002, he published groundbreaking, peer-reviewed research that demonstrated a strong correlation between the varying cancer rates in different areas of the U.S. and regional variations in average sunlight exposure.

His research into sunlight and cancer rates began in the late 1990s, when something surprising in the Atlas of Cancer Mortality Rates in the U.S. caught his attention. Dr. Grant noticed that many cancers had mortality rates about twice as high in the northeast as in the southwest. He first tried to see whether these variations could be explained based on dietary differences between the two areas, but found a U.S. Dept. of Agriculture report showing that the differences were less than 10-20 percent, which would not be sufficient to account for the differences in cancer rates.

These intriguing findings prompted Dr. Grant to examine pioneering work by three professors at the University of California School of Medicine—Drs. Cedric and Frank Garland and Dr. Edward Gorham. Their research had linked sun-induced vitamin D production to reduced risks for breast, colon, and ovarian cancer. He also found that Dr. Gary Schwartz of Wake Forest University had found a similar link between vitamin D and prostate cancer in the early 1990s.

Since many cancers have patterns similar to breast, colon, and ovarian malignancies, Dr. Grant reasoned that they might bear a similar relation to UVB radiation and the vitamin D it creates in the body. Dr. Grant decided to compare the cancer maps with regional sun exposure. Because he worked for NASA, he was well aware of the agency’s satellite measurements of UVB radiation over the U.S.. These reports showed that UVB levels in July (a peak period) vary with latitude, and, to a lesser extent, with elevation.

In a discovery that made headlines, Dr. Grant uncovered a statistically significant correlation between lower average sun exposure and higher death rates from a number of common cancers. His research identified an additional 8 vitamin-D-sensitive cancers, and he estimated that 17,000 to 23,000 Americans die prematurely from cancer annually due to insufficient sun (UVB radiation) exposure.

After publishing these landmark findings, Dr. Grant worked to confirm their significance by factoring in potentially confounding factors such as urban versus rural residence, smoking, alcohol consumption, race, and economic status. This research lengthened the list of vitamin D-sensitive cancers to 17. He also increased the estimate of premature cancer deaths caused by insufficient UVB and vitamin D to 50-60,000 extra fatalities per year, versus about 9,800 people who die of melanoma and skin cancer.

Has sun-avoidance advice gone too far?

If Dr. Grant is correct, lack of sunlight-produced vitamin D causes five to six times more cancer deaths than are caused by cancers related to excessive sun exposure. This estimate of avoidable extra deaths constitutes a sobering 10 percent of all U.S. cancer deaths.

As he told us in a recent conversation, “The results of my ecologic study showed that exposure to UVB radiation—the kind needed to produce vitamin D, and the kind blocked the most by common sunscreens—correlates inversely with 17 types of cancer: primarily cancers of the digestive and reproductive systems. In other words, the more sunlight a region receives, the lower are its rates of these cancers.

“I also found that the rates of six types of cancer—breast, colon, endometrial, esophageal, ovarian, and non-Hodgkins lymphoma—correlate inversely to both the amount of UVB radiation a region receives and to residence in rural areas, which results in greater average sun exposure, compared with residence in urban areas.”

In other words, it may be riskier to get too little sun than to get too much sun. The ideal, of course, is to practice moderation. Also, be aware that the darker your skin—hence the more UV-blocking melanin you have in it—the more sun you need to produce sufficient vitamin D: a proposition supported by the higher diagnostic rates and lower survival rates for vitamin-D-inhibited cancers found among African-Americans.

To help pursue his new interests, Dr. Grant founded and directs the Sunlight, Nutrition and Health Research Center (SUNARC), an organization “devoted to research, education, and advocacy relating to the prevention of chronic disease through changes in diet and lifestyle.” I urge you to visit his site——which is loaded with intriguing information about vitamin D and disease prevention.

To summarize, vitamin D research by Dr. Grant and others indicates that you need much more than the minimum RDA for maximum reduction of cancer risk. We’ll have more on the benefits of vitamin D next time.

The Neglected Nutrient Part 2: Vitamin D for Bones

Baby boomers face fractured futures, absent adequate “D”
by Craig Weatherby

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

A: Both display a tendency toward vitamin D deficiency.

Historical accounts indicate that rickets was common in 19 th century 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, and taking calcium and vitamin D supplements—or eating foods rich in calcium and vitamin D—can slow down or even reverse osteoporosis.

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 who do not eat oily, vitamin D-rich fish or milk fortified with smaller amounts of vitamin D. 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.

Current RDAs and safe upper limits

U.S. recommended daily allowances (RDAs)

Infants 0–12 months — 200 IU
Males and females 1–50 years — 200 IU

51–70 years — 400 IU
71 years and older — 600 IU

Pregnant women — 200 IU
Nursing women — 200 IU

U.S. safe upper limits for daily vitamin D intake

Infants 0–12 months — 1,000 IU

Children 1 year and older — 2,000 IU

Pregnant/nursing women — 2,000 IU

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

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. 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.

Fatty fish to prevent fractures

As we noted in our last issue, the best food sources of vitamin D—by far—are fish rich in oil (and omega-3s), such as salmon, sardines, sablefish, and tuna. (An eight-ounce glass of fortified milk provides only 100 IU.)

Sardines shine when it comes to bone health, because they provide both calcium and vitamin D. A one-quarter cup (2.2 oz.) serving of Vital Choice Sardines (one-half of one 4-3/8 oz. can) provides 234 mg of calcium (20 percent of the RDA), and about 285 IU of vitamin D3 (70 percent of the RDA for adults).

And, a standard 3.5 oz. serving would provide even more: about 375 mg of calcium (30 percent of the RDA), and about 460 IU of vitamin D3 (115 percent of the RDA).

A single 3½ ounce serving of salmon provides 360 IU of vitamin D, while a serving of tuna provides a bit more than half the RDA (233 IU).

It’s nice to know that one food group—fatty fish—offers two of the most important health-enhancing nutrients: omega-3s and vitamin D!

The Neglected Nutrient Part 3: Vitamin D vs. PMS

Together, vitamin D and calcium may reduce the risk of developing PMS
by Craig Weatherby

We’d intended to address vitamin D’s relationship to reduced risk of multiple sclerosis (MS) in part 3 of our series, but our plans were changed by headlines that appeared last week. It seems that vitamin D and calcium may play important roles in preventing premenstrual syndrome (PMS).

As every woman knows, the term PMS describes a cluster of emotional and physical symptoms that manifest about five to 10 days before the start of menstruation, and fade when menstruation begins.

PMS affects up to three in four women of childbearing age, usually during their late 20s and early 40s. It is most common among women with at least one child, those with a family history of major depression, and women with a history of postpartum depression or mood disorders. About one in five of all women with PMS suffer severe symptoms.

Lower vitamin D and calcium intake linked to higher PMS risk

Walter Willett, M.D.—the renowned Harvard University researcher mentioned elsewhere in this issue (see “Customer Query”)—started the Nurses’ Health Study II in 1989. As a “prospective” study, its purpose was to follow a large group of women over time, and thereby examine the possible links between their diets and lifestyles on risk of various diseases. The participating female nurses answered food questionnaires and other health surveys in 1991, 1995, and 1999.

In the new study, researchers led by Elizabeth Bertone-Johnson, M.D. of the University of Massachusetts compared the diets of about 1,000 Nurses’ Health Study participants with PMS and about 2,000 participants without PMS. They found that the women without PMS appeared to eat more foods rich in vitamin D and calcium, while the women with PMS had lower blood levels of calcium and vitamin D.

The results of earlier studies indicated that supplemental calcium might ease PMS symptoms. However, the new findings suggest that calcium and vitamin D may both be important for reducing the risk of PMS, possibly by influencing body levels of estrogen, the female sex hormone.

After accounting for factors like age, the number of children borne, and smoking, the researchers concluded that intake of vitamin D and calcium had the strongest correlation with risk of PMS: in other words, the women with the highest intake of vitamin D and calcium enjoyed a significantly reduced risk of experiencing PMS.

Increasing your vitamin D intake

As we noted in our previous vitamin D articles, most experts believe that the current vitamin D recommended daily allowances (RDA)—200 IU up to age 50, 400 IU after that—are much too low. For example, the Harvard School of Public Health recommends that everyone over age two consume 1,000 IU per day.

According to the National Institutes of Health, sardines, salmon, mackerel, and tuna are by far the richest dietary sources of vitamin D. (Cod liver oil contains even more, but its high vitamin A content blocks absorption of some of its vitamin D.)

One 3.5 oz. serving of sardines or salmon will provide a dose of vitamin D that approximates the recommended daily allowance (RDA) of 400 IU, while a 3.5 oz. serving of tuna provides one-half of the RDA (200 IU).

Increasing your calcium intake

When it comes to calcium, the richest food sources are sardines and low-fat milk and dairy products. (Removing some of the fat from milk and dairy foods increases the relative amount of calcium.) Sardines contain about 600 mg of calcium per 3.5 oz. serving (one-half the RDA), which equals the average calcium content of cheese. Some health experts—including the Harvard School of Public Health—question the wisdom of relying too much on milk and dairy foods for calcium. Instead, you can meet the adult RDA of 1,000 to 1,200 mg a day by eating other relatively high-calcium foods and/or by taking calcium supplements.

After sardines and dairy foods, good calcium sources include canned salmon with bones (210 mg per 3.5 oz serving), dark leafy greens, tofu, and dried beans. You can also choose calcium-fortified foods, including some brands of bread, soy milk, and orange juice.

The Neglected Nutrient, Part 4: Vitamin D vs. Multiple Sclerosis

Risk of debilitating disease found reduced by moderate sun exposure and fatty fish
by Craig Weatherby

We spoke with former NASA physicist William Grant, Ph.D.—now a leading vitamin D researcher—for the first part in this series, concerning vitamin D and cancer. At the time, Dr. Grant noted that the nutrient also appears to help prevent multiple sclerosis (MS): the degenerative disease that disrupts communication between the brain and other parts of the body.

As Dr. Grant says on his Web site (, it’s been known since the early 20th century the incidence of MS increases as you go north to higher latitudes. In other words, your risk of MS grows with your distance from the equator.

Sunlight is the primary “source” of vitamin D—followed by rich, cold-water fish and, as we’ll see, vitamin D helps prevent MS. This is why the increased risk of MS at higher latitudes is linked primarily to reduced sunlight exposure. Researchers estimate that if all Americans lived in southern U.S. states, the number of MS cases would drop from 400,000 to 200,000.

Note: The risk of MS also grows as consumption of saturated fat increases, and people living in northern latitudes tend to eat more of it, which is concentrated in red meats and dairy foods. However, this correlation is not as strong as the one between reduced sun exposure and increased MS risk.

What is MS?

Most researchers consider MS an autoimmune disease in which the body’s immune system attacks its own tissues: in this case, the myelin sheath that insulates nerve, causing “short circuits.” These autoimmune assaults may be triggered by unknown environmental factors, or infectious agents such as viruses.

Most people experience their first symptoms of MS between the ages of 20 and 40. Symptoms range from fairly minor to devastating, and can wax and wane mysteriously, leading to years of misdiagnosis. While MS can leave you unable to write, speak, or walk, the vast majority of patients experience moderate symptoms, including vision problems, muscle weakness in their extremities, or impaired coordination and balance.

There is no cure for MS, and many MS medications—primarily anti-inflammatory steroids such as ACTH and prednisone —have serious side effects, while some pose significant risks. Fortunately, many patients do well with no therapy.

Low vitamin D intake figures as key risk factor

A considerable body of evidence indicates that ultraviolet B (UVB) radiation from the sun—and the vitamin D it generates in the skin—are important risk-reduction factors for multiple sclerosis.

This excerpt from one recent review of the scientific literature summarizes the situation succinctly: “A number of epidemiological [population] studies have shown a protective effect of exposure to sunlight during early life and a recent longitudinal study [in which researchers observe participants over time] confirmed that vitamin D supplementation reduced life-time prevalence of MS in women. … Prevention of MS by modifying an important environmental factor (sunlight exposure and vitamin D level) offers a practical and cost-effective way to reduce the burden of the disease in the future generations.”

Researchers believe they know how vitamin D reduces the risk of MS:

Vitamin D plays a role in helping the immune system distinguish body tissues from foreign material. In MS, the body seems to mistake its own nerve-insulating myelin sheath for foreign tissue, and tries to destroy it.

Vitamin D regulates important aspects of the immune response—specifically, T helper cell and dendritic cell functions—in ways that decrease the intensity of the autoimmune response and the severity of symptoms.

In addition to being a natural “immuno-regulator,” vitamin D exerts anti-inflammatory effects. (Uncontrolled, tissue-damaging inflammation is a hallmark of autoimmune disorders like MS and rheumatoid arthritis.)

The RDAs for vitamin D: too low for too long

Current U.S. RDAs* and safe upper limits

Infants 0–12 months — 200 IU (5 mcg)
Males and females 1–50 years — 200 IU (5 mcg)

51–70 years — 400 IU (10 mcg)
71 years and older — 600 IU (15 mcg)

Pregnant women — 200 IU (5 mcg)
Nursing women — 200 IU (5 mcg)

U.S. safe upper limits for daily vitamin D intake

Infants 0–12 months — 1,000 IU (25 mcg)

Pregnant and nursing women — 2,000 IU (50 mcg)

Males and females 1 year and older — 2,000 IU (50 mcg)

* recommended daily allowances

Almost all vitamin D researchers believe that optimal vitamin D intake for adults lies in the range of 1,000 to 2,000 IU per day. Yet, the U.S. recommended daily allowance (RDA) for adults ranges from 200 to 600 IU, depending on age and maternal status (see “Current RDAs and safe upper limits,” to the right). Many expect the U.S. Institute of Medicine to raise the RDAs in the near future: a change that can’t come too soon for enhanced prevention of cancer, osteoporosis, and MS.

One way you can increase your vitamin D intake is through moderate sun exposure, in the range of 20 to 30 minutes per day. As noted in our article on vitamin D and cancer-prevention, most experts believe that the power of the vitamin D generated by sun exposure to help prevent many common cancers far outstrips the increased risk of skin cancer.

Another way to boost your body level of vitamin D is to enjoy ample amounts of rich, cold-water fish, such as salmon, low-mercury tuna, halibut, sablefish, and sardines.


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