Ancient Greeks used to pray to Apollo, the sun god, to stop epidemics and cure diseases. Turns out they weren’t far wrong: sunlight is vital to human health, as modern Canadians have learned to our cost.
For a whole generation—on doctors’ advice—we have slipped on shirts, slapped on hats, slopped on sunscreen and shirked the sunshine to avoid skin cancer. We have cut back on eggs and milk to reduce risk of heart disease, and we have curbed our appetite for cod-liver oil, mackerel and wild salmon.
We have cut ourselves off from the sources of vitamin D.
Result? It is estimated that 97 per cent of Canadians are vitamin D deficient in winter and most of us have insufficient levels even in summer. Some researchers believe lack of the “sunshine vitamin”—so-called because our bodies make it when summer sun hits our skin—causes some scourges of modern civilization. If they are right, a nutrient costing pennies a day could dramatically cut risks of scores of diseases and debilitating conditions. If they are right, it is a public health blunder—one that has resulted in ballooning health-care costs and affected the health of millions.
“If you can lower the cost of treating so many chronic diseases by addressing one simple issue,” says Rapson, “think of all the money you save. And it’s dirt cheap to treat it.”
“If I had a child with autism and my theory is true, I’d be furious,” says Dr. John Cannell, a psychiatrist and executive director of the U.S. Vitamin D Council. His controversial theory proposes declining levels of vitamin D in pregnant women and young children could be a factor explaining the rise in autism. Proof could take years, he says, but he expects research will show autism rates increase in higher latitudes.
You do not expect high emotion in a scientific debate about vitamins, but it does not take long to find it in the controversy over vitamin D.
“I feel guilty myself,” says Cannell. “I was a GP (general practitioner) in the 1980s and did the same thing—told people to avoid the sun and didn’t tell them about vitamin D. Once you tell someone to stop making vitamin D—which is exactly what you did if you told them to stay out of the sun—you have an affirmative duty to ensure they can make up for the loss,” he says.
Given increasing weight of scientific evidence, some nutritionists, doctors, and D researchers are anxious to see a dramatic adjustment in the dietary reference intakes for vitamin D—to cut down on incidence of diseases that could be prevented or ameliorated by supplementing with D. Others want to wait for results of further research.
Health Canada’s daily adequate intake of vitamin D is 200 IU (international units) for people under 50 years of age; 400 IU for those 51 to 70; 600 IU for people over 70. People over 50 are also advised to take a 400 IU supplement daily. The tolerable daily upper intake is 1,000 IU for infants and 2,000 for everyone else.
And that is not about to change soon.
“Health Canada is aware of the growing body of evidence on the role of vitamin D,” says spokesman Paul Duchesne. “But we believe recommendations issued by other organizations are premature” and a comprehensive review of benefits and safety is needed before any revisions.
Such a review could be done by the Institute of Medicine (IOM), based in Washington, D.C., which sets dietary reference intakes (DRIs) for vitamins and minerals for Canada and the United States. Due to the volume of work involved, this process can take a considerable amount of time.
The IOM has begun examining what needs to be changed for the next DRI process and is waiting for the U.S. and Canada to ask for, and fund, a review. “We’re ready,” says Linda Meyers, director of IOM’s Food and Nutrition Board. She estimates it would take about a year from the time a committee is formed to investigate vitamin D and related nutrients to the time a new recommendation is made.
Since vitamin D DRIs were last set in 1997, that is too long a time for some. “We’ve looked at over 60 studies published since 2001 just on cancer alone and vitamin D,” says Heather Chappell, senior manager of cancer control policy with the Canadian Cancer Society. “We felt there was enough evidence.” Vitamin D deficiency has been linked to a score of different forms of cancer. One study showed people rich in vitamin D have up to a 77 per cent lower overall cancer risk. The society recommends 1,000 IU daily for adults in fall and winter (year-round for those at risk), plus a few minutes daily unprotected summer sun exposure.
The Canadian Pediatric Society recommends pregnant and breastfeeding women take 10 times Health Canada’s daily adequate intake—2,000 IU—and full-term infants be given 800 IU in fall and winter, plus a few minutes of daily sunshine exposure. Adequate D status in mothers and infants “may have lifetime implications,” it says.
Vitamin D deficiency is “so widespread it’s not a question of each person going to a physician and getting treatment,” says Susan Whiting, a University of Saskatchewan nutrition professor who has been telling scientific conferences for years that it is critical to raise DRIs and begin educating the public. Public health initiatives are common whenever effects of disease can be lowered for the whole population—that is why we have public sewage systems, treated drinking water, vaccination programs and campaigns to urge people to stop smoking or take up exercise. Vitamin D is a natural for such a campaign.
Raising the DRIs is an important public health issue because those numbers are supposed to reflect adequate amounts of nutrients to avoid deficiency diseases, reduce chronic diseases and keep us from taking toxic amounts. They are the basis of government policies, like Canada’s Food Guide, and are used to determine how much D will be put into the nation’s milk supply and vitamin capsules, nutrient labels on food packages in supermarkets, menus for long-term care homes, day-care centres and school cafeterias.
Doctors are finding the amount of D circulating in Canadians’ blood streams falls short of that associated with optimal health. People who work in the sunshine have circulating levels of 25 dihydroxyvitamin D of up to 150 nmol/L (nanomoles per litre, a measure of a substance concentrated in a liquid), and those with rickets and osteomalacia have levels below 27.5 nmol/L. At 80 to 100 nmol/L there is a dramatic decline in risks of various cancers, heart disease, multiple sclerosis, lupus, autism, Alzheimer’s disease, influenza, depression, muscle pain and fatigue, pain, high blood pressure, tuberculosis, influenza, the common cold, periodontal disease, schizophrenia—and the list is growing.
Yet it is rare for physicians to find patients who reach 80 nmol/L, says one doctor who has been testing patients regularly for three years. “The lowest I’ve ever recorded is 11 nmol/L,” says Dr. Linda Rapson, a pain specialist in Toronto and chair of the Ontario Medical Association’s complementary medicine section. “I’ve come to see anything below 100 as not a good thing.” She’s seen dramatic improvements in patients’ pain when their D levels increase. “The best diagnosis you can make is to find a really low level because you know there’s a whole lot of help you can give a person just by giving them vitamin D.”
“Roughly four per cent of people in Edmonton are in the rickets range (about 25 nmol/L),” says Dr. Gerry Schwalfenberg, family medicine lecturer at the University of Alberta, who has tested D levels for a study to be published later this year. For years Schwalfenberg, also a family doctor, has recommended patients take cod-liver oil daily, which has about 400 IU, but still found “67 per cent were not in normal range.” He said doses of 1,000 IU daily will raise about half the population from the average of 60 nmol/L, but it takes “closer to 2,000 IU to get people into the optimal range.”
“If you can lower the cost of treating so many chronic diseases by addressing one simple issue,” says Rapson, “think of all the money you save. And it’s dirt cheap to treat it.” The cost of vitamin D deficiency to the Canadian health-care system is a minimum $9 billion annually, says Dr. William Grant of the Sunlight, Nutrition and Health Research Centre.
Consider the savings if incidence is lowered of just one disease targeted by researchers. Diabetes costs $13.2 billion annually, a cost expected to rise to $19.2 billion by 2020. At least five per cent of Canadians have diabetes, up from three per cent just a decade ago. Diabetics cost our health-care system two to three times as much as non-diabetics. Diabetes can lead to heart disease, kidney disease, eye disease, nerve damage (each with their own costs). About 80 per cent of diabetics die from heart disease or stroke, which in turn cost $18.5 billion annually, and their lives are five to 15 years shorter, time when many could have been working and paying taxes.
Studies indicate vitamin D might reduce diabetes risk. In Finland, 10,366 children were given 2,000 IU of vitamin D daily for a year after they were born, reducing their type 1 diabetes risk by 80 per cent over the next 31 years. A 17-year U.S. study of about 4,000 adults showed people with higher blood levels of D had a 40 per cent lower risk of developing type 2 diabetes.
The Health Council of Canada puts the diabetes ‘epidemic’ down to aging, inactivity and obesity. Overweight people have lower D levels partly because excess body fat locks in D, which is used to produce leptin, a hormone that signals people to stop eating. So, the more fat you carry, the less full you feel. Increasing D can reboot leptin production, the “full” signal is received and it is easier to lose weight. Vitamin D also helps determine whether the body uses calories as energy or stores them as fat. Eating less and using more energy are both key to weight loss, and one study shows every kilogram of body weight lost reduces diabetes risk by 16 per cent.
Treatment costs could go down, too. Another study showed increasing diabetics’ blood levels of D to 75nmol/L improves insulin sensitivity by 60 per cent; that is more than some prescription drugs—and cheaper. Prescriptions can run $150 monthly; a daily dose of 1,000 IU vitamin D costs as little as $16 a year. But this research doesn’t mean anyone should swap their medication for vitamin D.
The Canadian Diabetes Association takes a cautious position on the debate. “We’d be happy to recommend anything that would prevent the onset of diabetes or (its) complications,” says Sharon Zeiler, registered dietitian in charge of nutrition for the Canadian Diabetes Association. “But we’re waiting for very strong evidence. Our concern is protecting the health of people with diabetes; we don’t want to put them at risk.” The association follows the Canada Food Guide recommendation of a 400 IU supplement for people over 50. “Initial studies are interesting and we would like to see more in terms of long-term studies on the relationship between vitamin D and diabetes,” adds spokesman Jeremy Brace.
Many are cautious about jumping on the bandwagon.
“I think you have to have the right science before you can go forward,” says Dr. Stephanie Atkinson, a pediatrics professor at McMaster University in Hamilton, Ont. She chaired the IOM panel on calcium and related nutrients that set the vitamin DRI in 1997. “It’s very hard to take epidemiological evidence and turn it into nutrient requirements because there are so many confounding variables. I know there are a lot of people impatient about it, but they just don’t understand to be responsible you need a good body of science (and) good methodology in place.”
“The upside is so huge, it’s incredibly frustrating,” says Joseph Levy, executive director of Canada’s Vitamin D Society, formed to encourage public debate. He blames inaction on politics—and the fact there is little money to be made from vitamin D. “Sunlight is free, and vitamin D is very inexpensive.”
Critics “look at vitamin D as the latest ‘hot nutrient’ and recall how other hot nutrients fell out of favour,” says Reinhold Vieth, nutritional sciences professor at the University of Toronto. But other vitamin trials used artificially high doses of substances the body
normally uses in minuscule amounts. “The vitamin D story is putting into human beings the amount of vitamin D they should have had all along.”
Vitamin D is actually a hormone that humans manufacture and store in their own bodies. In contrast to other vitamins, the body needs large amounts of it: vitamin D receptors are found in all organ systems and in most cells in the body; it facilitates absorption of nutrients in the digestive system, builds a strong skeleton, promotes muscle strength, maintains an effective immune system, turns genes on and off.
Unlike other vitamins, the list of Canadian foods containing vitamin D is short: fatty fish, egg yolks and fortified foods like milk. To get enough D, Canadians need food, supplements and the sun.
When ultraviolet B radiation (UVB) in sunshine hits the body, a cholesterol under the skin is converted into previtamin D, which is metabolized by the liver and kidneys into the hormone calcitriol. However, UVB is easily screened by clouds, smog and moisture in the air, so the sun needs to be more than 45 degrees above the horizon for enough UVB to reach the earth. That means the sun is at the wrong angle anywhere in the Canadian sky for at least six months a year. If you sit out in a bathing suit under summer sun between 10 a.m. and 3 p.m. for five to 30 minutes (depending on skin colour) “you make more vitamin D in your skin than exists in 200 glasses of milk,” says Cannell. Yet no one overdoses because the body regulates how much D is made from sunshine.
“Fifteen minutes a day should be OK,” says Dr. Youwen Zhou, a skin oncologist with the B.C. Cancer Agency and spokesman for the Canadian Melanoma Foundation. But he warns when that is not enough to top up D levels, more sun is a bad idea, because it damages skin and raises risk of skin cancer. “It’s better to stay away from excessive skin exposure and take vitamin D supplements.”
Sun is our best vitamin D source, explains Whiting, who was on the IOM committee on DRIs and nutrition labelling. But adequate sun exposure “is a complicated message” because individuals’ needs vary depending on latitude, skin colour, weight, age, season and amount of clothing worn. Increasing the amount in fortified food, and fortifying more foods would help, but choosing which foods to fortify is not easy, either, because many people have food intolerances. People with a darker skin tone have the highest need for extra D (melanin in their skin hampers D production) and they are also more likely to be unable to digest milk. It might look easy to move on to other foodstuffs, but which ones do most people actually eat? “It’s a slow process,” she says.
Supplements could provide universal coverage, said Whiting, but Canadians have a bad record in keeping to supplement regimes, and some people just cannot afford it. “We need guidelines that don’t require every single person to think about what they have to do” to get enough D every day. Also, “we don’t want people to take huge supplement amounts” for fear of toxicity. “There’s a point at which calcium starts to deposit in soft tissue like blood vessels and kidneys.”
Recent research by Dr. Armin Zitterman of Germany’s Westfalia Heart Center shows it is much more common for calcification to occur with very low doses of vitamin D. Lacking enough D to usher it into bones, calcium combines with cholesterol to form plaque in blood vessels. He says it takes “many hundreds of thousands of IUs” daily for calcification to occur from overdose of vitamin D.
“It’s quite a safe compound,” adds Vieth. “The safe level extends well beyond what you would normally imagine yourself taking from an over-the-counter product.” He knows of doctors who have prescribed 40,000 IU per day over months with no ill consequence.
Yet Health Canada recommends that Canadians not exceed the 2,000 IU tolerable upper intake level “from all sources of vitamin D, including milk and over-the-counter supplements.” There have been no deaths attributed to vitamin D overdose in Canada, and only nine suspected overdoses—‘suspected’ because the victims had taken massive doses of other substances as well.
“I’m at one end of a pendulum,” says Vieth. “The people who actually do the research, who are very close to the numbers, are entirely convinced” vitamin D is safe and beneficial to just about everybody (save for those with a few rare health conditions).
The debate is far from over, and there will be more high emotion and argument before the issue is resolved. “I’ve been lucky to hear the wild disagreement,” says Whiting. “If you don’t know the whole spectrum of ideas, you can’t see how we really need people to think long and hard about this.”
But while the experts debate the issue, what are ordinary Canadians to do in the interests of their own best health?
Schwalfenberg wants doctors to start acting now. “We should be doing far more blood levels,” he says. “I think it should be part of a complete physical, though it’s not been adopted as standard of care.” Most provinces pick up the cost of a vitamin D test, he says. “It’s expensive—$50 a test—but you’re going to prevent a lot of (deficiency) problems.” He advises family doctors to have “a high index of suspicion that people are not getting enough” vitamin D.
And people can take matters into their own hands. The Vitamin D Society recommends regular, moderate summer sun exposure, intelligent supplementation and having vitamin D levels tested. “Dietary allowances are not the end point in vitamin D health,” says Levy. “Blood levels are.” And those can be measured by family doctors. Patients can request a test (known as a 25-hydroxyvitamin D test) and develop a plan with their doctors to bring up their blood levels if needed. The society says the optimal level is 125 nmol/L.
Prayers to Apollo are not necessary.
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