Voicing An Impatient Note On Vitamin D 

By Cathy Kristiansen

 

Scientists worldwide are singing vitamin D's praises con forza, but government health authorities are so far sticking to the same old refrains about the best vitamin D intake levels.

Millions of people unwittingly have too little of the hormone to optimize their long-term health, according to an increasing number of researchers and physicians who are assessing vitamin D data. Large chunks of Western populations are now identified as vitamin D-deficient.

"The lack of vitamin D is responsible for an incredible array of diseases," said Bruce W. Hollis, Ph.D., professor at the Medical University of South Carolina in Charleston. Insufficient levels have been linked to bone anomalies, various cancers, diabetes, depression, multiple sclerosis, autoimmunity, cardiovascular disorders, and other chronic diseases. People could protect themselves against these ailments by taking enough supplements; but without the encouragement of "official" health agencies, most won't take enough. "The major issue remains that the recommendations - still don't match what's really needed," said Dr. Hollis.

Taking a Shine to Supplements

Although the body's conversion of ultraviolet B (UVB) rays into vitamin D is the overwhelming source around the globe, many people do not have enough sun exposure. Reasons include higher latitudes in winter, darker pigmented skin, sunscreen use, cultural mores to cover much of the skin, and lifestyles that curb outdoor time.

Vitamin D supplements are cheap, easy to take, and fill the supply gap well, but how much of them is optimal or safe is controversial, with some of the research findings dramatic and relatively new. Moreover, some earlier studies found hypercalcemia at relatively low vitamin D levels; although debunked, they still cast a shadow on safety assessments of non-solar vitamin D intake.

Cloudy U.S. Advice

The "official" U.S. advisory body for vitamin D is the non-profit Institute of Medicine (IOM) of the National Academies. In 2008, it launched a study to assess vitamin D research and see if its 1997 recommended daily allowances are appropriate.1

The institute currently suggests, in conditions of "insufficient sunlight," 200 IU daily for newborns to 50-year-olds, including pregnant and lactating women; 400 IU for ages 50-70; and 600 IU above 70 years. Stated safe upper limits are 1,000 IU daily up to 1 year of age, then 2,000 IU.

The IOM lists food sources as "fish liver oils, flesh of fatty fish, liver and fat from seals and polar bears, eggs from hens that have been fed vitamin D, fortified milk products, and fortified cereals."1 The range is small, however, and problematic for people who dislike fishy tastes or who are lactose intolerant. Even with broad diets, food rarely contributes enough vitamin D, and most countries fortify food minimally if at all.

An IOM spokesperson said of the current review: "The point was to look and see, are any changes needed?" Asked if there's any indication yet that levels will be raised, she replied, "No comment. It's going to depend on what the body of science shows." Although the study is intended to wrap up in "summer this year," the target might slide, she said. "Frankly, one of the steps is to have a peer review; that can take time."

Many scientists remain skeptical that the panel will increase its recommendations by nearly enough. "Being they are very conservative, I don't get the feeling they are going to raise the levels to what they ought to be," said Dr. Hollis.

Spotlight on Children

A professional organization with sway in pediatricians' offices, the American Academy of Pediatrics (AAP), in 2008 raised its recommendations for vitamin D, last updated in 2003.2 The group now advises "a minimum intake" of 400 IU daily for children and adolescents (some babies receive this via formula), but this is still less than what many experts say is needed.

Some diseases linked to vitamin D deficiency affect children more than adults, including rickets and juvenile diabetes. Moreover, many adult diseases might be germinating in children with insufficient vitamin intake. Two studies last year in the AAP's Pediatrics highlighted that 70% of U.S. children have deficient 25-hydroxy vitamin D levels (9% < 15 ng/ml) or insufficient (61% 15-29 ng/ml).3, 4These children also had higher blood pressure, lower HDL cholesterol, and elevated parathyroid hormone that undermines bone mineral density.

Jared Reis, Ph.D., now at the U.S. National Heart, Lung, and Blood Institute, who led one of the studies, said, "It appears that the current recommendations are low. But particularly with cardiovascular disease, this is a relatively new area of research and there hasn't been a lot of time to generate a lot of data."

Pointing to AAP's recent raised recommendations, he said, "This provides evidence that people are starting to think more about what an adequate intake of vitamin D should be. We do need to reevaluate the most recent scientific evidence and make recommendations for all Americans."

Lighting their Own Way

Even with little change in official U.S. vitamin D advice, many patients are listening to the chorus of scientists advocating higher intake. Dr. Hollis noted, "Physicians are doing a lot of testing" and the supplement market has exploded, totaling $250 million in 2009 compared with $50 million the previous year.

John Jacob Cannell, M.D., executive director of the Vitamin D Council, a self-appointed group of experts working to increase global awareness of vitamin D deficiency, gives this advice at www.vitamindcouncil.org: "If you use suntan parlors once a week or if you live in Florida and sunbathe once a week, year-round, do nothing. However, if you have little UVB exposure, my advice is: healthy children under the age of 1 year should take 1,000 IU per day-over the age of 1, [add] 1,000 IU per every 25 pounds of body weight per day. Well adults and adolescents should take 5,000 IU per day."

Dr. Hollis, who is also on the council, volunteers that he takes 4,000 IU daily.

Dawning Worldwide Awareness

The United States is in the vanguard of vitamin D research and testing, so it is unsurprising that national recommendations elsewhere mostly focus on the minimum dose needed to avoid bone disease and do not yet incorporate discoveries about the hormone's long reach in other areas. Even governments now reviewing their advice are unlikely to decide on new levels for years, experts say.

Dr. Hollis singled out China as slow to focus'; similar are Middle Eastern countries, apart from the United Arab Emirates, which tests vitamin D levels fairly extensively. Australian public health authorities have greatly increased testing in the past 2-3 years, and France's public health system is one of the most proactive in combating deficiency. He rued the United Kingdom's particular slowness to adapt, with its financially restrained national health system.

Fog in England

Also bemoaning the lack of awareness in England is Benjamin Jacobs, M.B., a pediatrician at Northwick Park Hospital in Harrow. "I have been seeing patients for 22 years; in the first 10, I saw hardly any cases of rickets, but now see 2-3 cases every month. It has come right back as a common disease," he said.

Most children do not receive any vitamins, even though they are available without prescription. Physicians cannot widely prescribe vitamins under the government-funded health system. The only vitamin-D fortified food is simple margarine.

Regarding his patients, Dr. Jacobs advises parents to give them 400 IU per day-the current official recommendation- even though he believes double that would be safe and better for their health. "Higher doses seem to prevent a lot of other diseases. To have that sort of effect, you seem to need 800 or 1,000 IU/day ... I think it's a very safe supplement, not like vitamin A. You can give 10 times our recommended dose of D for many months, if not years, very safely. Overdose is extremely rare and, in such cases, everyone recovered."

Dr. Jacobs, like Dr. Hollis, cited studies that inaccurately attributed high serum calcium levels to vitamin D overdose, making authorities wary about recommending too much supplementation. He sees vitamin D deficiency becoming worse before it garners more government attention. Some recent factors working against sufficient intake are successful public health campaigns to promote sunscreen use and breastfeeding-good campaigns, he said, but lowering vitamin D intake.

"We are much more conservative in this area than in the U.S. On the other hand, experts here feel the evidence is strong that we should be taking more vitamin D," he said. "It's a difficult public health question, but one thing we can't do is continue to ignore the problem."

Official recommendations come from the Committee on Medical Aspects of Food and Nutrition Policy (COMA) and National Health Service?s National Institute for Health and Clinical Excellence (NICE).

COMA, in 2005, recommended dietary vitamin D supplements for pregnant and nursing mothers of 10 µg (400 IU) and 7 µg (280 IU) for children under 5 years of age. Vitamin D supplements of 10 µg/day are also recommended for older people to maintain good bone health and to reduce the risk of fractures. For many decades last century, but no longer, COMA recommended that children take cod liver oil daily, equating to about 400 IU vitamin D per teaspoon.

NICE, in 2008, was bolder, publishing guidelines, including for pregnant and lactating women, saying children "at risk" for vitamin D deficiency should intake 400 IU/day to age 5; but "the vague phrasing means many children still fall through the cracks," Dr. Jacobs said.

Winter's Tale in Finland

Recent studies have shown that roughly half the Finnish population lacks healthy vitamin D levels in winter, according to Christel Lamberg-Allardt, Ph.D., at the University of Helsinki in Finland. This is even with D3 fortification of all fluid milk products, margarines, and spreads, and generally adequate vitamin D levels in fish eaters.

"Supplementation with 10 µg is recommended for children up to the age of 2 years and close to 90% of children up to the age of 1 get this," she said. "However, older children have lower vitamin D status and adolescent girls are considered a risk group."

Nordic countries are collaborating on joint official recommendations, but work won't begin until the spring of this year, with results not ready until 2012.

For now, physicians and researchers singing the vitamin D song can hope their voices will be heard by authorities and that eventually the curtain will close on global vitamin D deficiency. 

References:
  1. Information about the IOM study is at www.iom.edu/Activities/Nutrition/ DRIVitDCalcium.aspx. To see the IOM?s 1997 recommendations, visit www.iom.edu/dris, click "Table of DRI Values," then click "Vitamins Table."
  2. Wagner CL, Greer FR, Section on Breastfeeding and Committee on Nutrition. Prevention of Rickets and Vitamin D Deficiency in Infants, Children, and Adolescents. Pediatrics, 2008:122;1142-1152.
  3. Reis JP, von Mühlen D, Miller ER, III, Michos ED, Appel LJ. Vitamin D status and cardiometabolic risk factors in the United States adolescent population. Pediatrics, published online August 3, 2009.
  4. Kumar J, Muntner P, Kaskel FJ, Hailpern SM, Melamed ML. Prevalence and associations of 25-Hydroxyvitamin D deficiency in children and adolescents in the United States: results from NHANES 2001-2004. Pediatrics, published online August 3, 2009.