Older women who are overweight or obese and lose more than 15 percent of their body weight could significantly boost their levels of vitamin D.

Since vitamin D is generally lower in persons with obesity, it is possible that low vitamin D could account, in part, for the link between obesity and diseases such as cancer, heart disease and diabetes. The study, conducted in Seattle, America indicates that the surge in vitamin D could help scientists explore new avenues for the prevention of these chronic diseases.

Vitamin D is fat-soluble nutrient that plays many important roles in the body, including promoting calcium absorption and is needed for bone growth and bone healing. Along with calcium, vitamin D helps protect older adults from osteoporosis. The nutrient also influences cell growth, neuromuscular and immune function, and reduces inflammation. Many gene-encoding proteins that regulate cell proliferation, differentiation, and apoptosis (programmed cell death) are modulated in part by the vitamin.

It’s found in certain foods, such as fatty fish, and produced naturally in the body through exposure of skin to sunlight. Just 10 minutes of sun a day is enough to trigger adequate vitamin D production. The estimated average requirement via diet or supplementation is 400 international units per day for most adults. The optimal blood level of vitamin D is thought to be between 20 and 50 ng/mL, Levels under 20 ng/mL are inadequate for bone health and levels over 50 ng/mL are associated with potential adverse effects, such as an increased risk of developing kidney stones.

Researchers conducted a year-long study to assess the effect of weight loss on vitamin D. They assigned 439 overweight or obese postmenopausal women to one of four regimens: exercise only, diet only, exercise plus diet and no intervention. About 70 percent of the participants had less-than-optimal levels of vitamin D when the study began; at baseline, the mean blood level of vitamin D among the study participants was 22.5 ng/mL. In addition, 12 percent of the women were at risk of vitamin D deficiency (blood levels of less than 12 ng/mL).

Women who lost up to 10 percent of their body weight (10 to 20 pounds) through diet and exercise saw modest increases in vitamin D, those levels were roughly three times higher in women who dropped more than 15 percent of their body weight, regardless of dietary intake of the nutrient.

The researchers were surprised at the effect of weight loss greater than 15 percent on blood vitamin D levels. It appears that the relationship between weight loss and blood vitamin D is not linear but goes up dramatically with more weight loss. It is thought that obese and overweight people have lower levels of vitamin D because the nutrient is stored in fat deposits. During weight loss, it is suspected that the vitamin D that is trapped in the fat tissue is released into the blood and available for use throughout the body.

The findings suggest the greater the weight loss, the more meaningful the surge in vitamin D levels. However, the researchers noted that the degree to which vitamin D is available to the body during and after weight loss remains unclear. They also cautioned that more targeted research is needed to understand any link between vitamin D deficiency and chronic disease.

via Weight loss in the obese boosts vitamin D levels.

A long-awaited report from a panel of independent scientists recommends tripling the amount of vitamin D most Americans should take and small increases in calcium levels for children to build and maintain strong bones, but some specialists warned that the recommendations were flawed.

The Institute of Medicine panel’s findings, being released today, carry considerable weight — government agencies rely on the recommendations to set food policy, everything from product labeling to requirements for school lunch programs. And a raft of health-related organizations, such as the National Osteoporosis Foundation, use the guidelines to set their policies for nutrient recommendations for specific groups of patients.

Some research has suggested that consumption of even higher amounts of vitamin D could protect against heart disease and various cancers, but the panel said that after scrutinizing nearly a thousand studies, it could not find sufficient evidence that more vitamin D would be beneficial and safe.

It said the best evidence it could find showed that the new recommended levels of vitamin D and calcium were the optimum ones for building strong bones without risking harmful side effects.

“More is not necessarily better for vitamin D,’’ said panel member Dr. JoAnn Manson, a Harvard Medical School professor and chief of preventative medicine at Brigham and Women’s Hospital.

“We need to consider the lessons of other nutrients, such as vitamin E and beta-carotene, as cautionary tales,’’ Manson said, referring to earlier popular wisdom that those nutrients held promise as weapons against illnesses. “Randomized clinical trials did not find benefit and suggested harm.’’

For vitamin D, the panel tripled the daily recommended allowance from 200 international units to 600 units for people aged 1 to 50. It also recommended that amount for people up to age 70. Previously, the amount for that group had been 400 units. Over age 70, it recommended 800 units.

The guideline changes for calcium were less dramatic: The panel suggested 700 milligrams daily for children 1 to 3 years old, up from 500 now; and 1,000 mg. for 4- to 8-year-olds, up from 800. For most adults, the daily intake remains at 1,000 mg. It kept the recommended 1,200 mg. for women over 50, but reduced the amount for men that age to 1,000.

The guidelines have not been updated by the institute since 1997, and in the interim various organizations have issued their own recommendations, producing confusing and sometimes conflicting advice for consumers.

The 14-member panel also concluded that most laboratories are setting the bar too high when they measure whether patients have adequate vitamin D in their bloodstream, a test that then prompts physicians to prescribe higher doses.

“We are not making any blanket statements that if your doctor recommends high dose supplements that you should stop taking them,’’ Manson said.
Instead, she said, the panel’s aim was to spur consensus among labs to create more uniform, lower guidelines.

Other specialists who were invited by the panel to review its work said its recommendations for adequate vitamin D levels fell short, and that older patients especially would lose out.

Dr. Bess Dawson-Hughes, director of the Bone Metabolism Laboratory at Tufts University, said that the panel’s recommendations for how much vitamin D patients over age 60 should have in their blood stream was too low.

She said her studies and those of other researchers have shown that older patients need higher levels of D in their blood stream than the panel recommended.

“The older population will have fewer fractures and falls, across the board, if they have higher (blood) levels,’’ said Hughes, who was a member of the 1997 panel that last updated the recommendations.

Otherwise, she said, she found the recommendations generally on target.

But Dr. Walter Willett, chair of the nutrition department at Harvard’s School of Public Health, said the panel’s recommendations for vitamin D were too low and its recommendations for calcium too high.

He said the panel’s conclusion that the “majority of Americans’’ are receiving adequate amounts of vitamin D is “flawed.’’ He said strong evidence indicates that most adults need nearly twice the amount of vitamin D that the panel recommended — at least 1,000 units a day, not 600. He said there is strong evidence that higher levels of vitamin D not only reduce the risk of fractures in older adults, they also reduce the risk for colon cancer.

Willett also said that other international panels of scientists, including the World Health Organization, recommend half the amount of calcium for adults, suggesting 500 milligrams daily, not 1,000. He said strong evidence suggested that elevated calcium levels increase the risk of fatal prostate cancer, and possibly ovarian cancer. He said that calcium is added to so many foods, such as orange juice, that Americans may unwittingly be consuming far too much calcium.

“These guidelines get translated to dietary policy . . . how many glasses of milk a day consumers should have . . . and schools have to conform to them, so they have a big downstream impact,’’ Willett said.

The federal departments of Health and Human Services and Agriculture are finalizing new daily guidelines, expected out by year’s end, on a broad array of nutrients.

A spokesman for the Agriculture Department said it is still studying the institute’s calcium and vitamin D recommendations.

A spokeswoman for the National Osteoporosis Foundation said her organization had not yet decided whether to change its recommendations for vitamin D intake. The foundation has recommended substantially higher levels of vitamin D for adults over 50 — as much as 1,000 units — than was included in the institute’s new guidelines.

via Calcium, vitamin D changes suggested – The Boston Globe.

Vitamin D promises to be the most talked-about and written-about supplement of the decade. While studies continue to refine optimal blood levels and recommended dietary amounts, the fact remains that a huge part of the population — from robust newborns to the frail elderly, and many others in between — are deficient in this essential nutrient.

If the findings of existing clinical trials hold up in future research, the potential consequences of this deficiency are likely to go far beyond inadequate bone development and excessive bone loss that can result in falls and fractures. Every tissue in the body, including the brain, heart, muscles and immune system, has receptors for vitamin D, meaning that this nutrient is needed at proper levels for these tissues to function well.

Studies indicate that the effects of a vitamin D deficiencyinclude an elevated risk of developing (and dying from) cancers of the colon, breast and prostate; high blood pressure and cardiovascular disease; osteoarthritis; and immune-system abnormalities that can result in infections and autoimmune disorders like multiple sclerosis, Type 1 diabetes and rheumatoid arthritis.

Most people in the modern world have lifestyles that prevent them from acquiring the levels of vitamin D that evolution intended us to have. The sun’s ultraviolet-B rays absorbed through the skin are the body’s main source of this nutrient. Early humans evolved near the equator, where sun exposure is intense year round, and minimally clothed people spent most of the day outdoors.

“As a species, we do not get as much sun exposure as we used to, and dietary sources of vitamin D are minimal,” Dr. Edward Giovannucci, nutrition researcher at the Harvard School of Public Health, wrote in The Archives of Internal Medicine. Previtamin D forms in sun-exposed skin, and 10 to 15 percent of the previtamin is immediately converted to vitamin D, the form found in supplements. Vitamin D, in turn, is changed in the liver to 25-hydroxyvitamin D, the main circulating form. Finally, the kidneys convert 25-hydroxyvitamin D into the nutrient’s biologically active form, 1,25-dihydroxyvitamin D, also known as vitamin D hormone.

A person’s vitamin D level is measured in the blood as 25-hydroxyvitamin D, considered the best indicator of sufficiency. A recent study showed that maximum bone density is achieved when the blood serum level of 25-hydroxyvitamin D reaches 40 nanograms per milliliter or more.

“Throughout most of human evolution,” Dr. Giovannucci wrote, “when the vitamin D system was developing, the ‘natural’ level of 25-hydroxyvitamin D was probably around 50 nanograms per milliliter or higher. In modern societies, few people attain such high levels.”

A Common Deficiency

Although more foods today are supplemented with vitamin D, experts say it is rarely possible to consume adequate amounts through foods. The main dietary sources are wild-caught oily fish (salmon, mackerel, bluefish, and canned tuna) and fortified milk and baby formula, cereal and orange juice.

People in colder regions form their year’s supply of natural vitamin D in summer, when ultraviolet-B rays are most direct. But the less sun exposure, the darker a person’s skin and the more sunscreen used, the less previtamin D is formed and the lower the serum levels of the vitamin. People who are sun-phobic, babies who are exclusively breast-fed, the elderly and those living in nursing homes are particularly at risk of a serious vitamin D deficiency.

Dr. Michael Holick of Boston University, a leading expert on vitamin D and author of “The Vitamin D Solution” (Penguin Press, 2010), said in an interview, “We want everyone to be above 30 nanograms per milliliter, but currently in the United States, Caucasians average 18 to 22 nanograms and African-Americans average 13 to 15 nanograms.” African-American women are 10 times as likely to have levels at or below 15 nanograms as white women, the third National Health and Nutrition Examination Survey found.

Such low levels could account for the high incidence of several chronic diseases in this country, Dr. Holick maintains. For example, he said, in the Northeast, where sun exposure is reduced and vitamin D levels consequently are lower, cancer rates are higher than in the South. Likewise, rates of high blood pressure, heart disease, and prostate cancer are higher among dark-skinned Americans than among whites.

The rising incidence of Type 1 diabetes may be due, in part, to the current practice of protecting the young from sun exposure. When newborn infants in Finland were given 2,000 international units a day, Type 1 diabetes fell by 88 percent, Dr. Holick said.

The current recommended intake of vitamin D, established by the Institute of Medicine, is 200 I.U. a day from birth to age 50 (including pregnant women); 400 for adults aged 50 to 70; and 600 for those older than 70. While a revision upward of these amounts is in the works, most experts expect it will err on the low side. Dr. Holick, among others, recommends a daily supplement of 1,000 to 2,000 units for all sun-deprived individuals, pregnant and lactating women, and adults older than 50. The American Academy of Pediatrics recommends that breast-fed infants receive a daily supplement of 400 units until they are weaned and consuming a quart or more each day of fortified milk or formula.

Given appropriate sun exposure in summer, it is possible to meet the body’s yearlong need for vitamin D. But so many factors influence the rate of vitamin D formation in skin that it is difficult to establish a universal public health recommendation. Asked for a general recommendation, Dr. Holick suggests going outside in summer unprotected by sunscreen (except for the face, which should always be protected) wearing minimal clothing from 10 a.m. to 3 p.m. two or three times a week for 5 to 10 minutes.

Slathering skin with sunscreen with an SPF of 30 will reduce exposure to ultraviolet-B rays by 95 to 98 percent. But if you make enough vitamin D in your skin in summer, it can meet the body’s needs for the rest of the year, Dr. Holick said.

Can You Get Too Much?

If acquired naturally through skin, the body’s supply of vitamin D has a built-in cutoff. When enough is made, further exposure to sunlight will destroy any excess. Not so when the source is an ingested supplement, which goes directly to the liver.

Symptoms of vitamin D toxicity include nausea, vomiting, poor appetite, constipation, weakness and weight loss, as well as dangerous amounts of calcium that can result inkidney stones, confusion and abnormal heart rhythms.

But both Dr. Giovannucci and Dr. Holick say it is very hard to reach such toxic levels. Healthy adults have taken 10,000 I.U. a day for six months or longer with no adverse effects. People with a serious vitamin D deficiency are often prescribed weekly doses of 50,000 units until the problem is corrected. To minimize the risk of any long-term toxicity, these experts recommend that adults take a daily supplement of 1,000 to 2,000 units.

Personal Health – What Do You Lack? Probably Vitamin D – NYTimes.com.

“It’s likely that more than one-third of older adults now have vitamin D levels associated with higher risks of death and few have levels associated with optimum survival,” said Adit Ginde, MD, MPH, an assistant professor at the University of Colorado Denver School of Medicine’s Division of Emergency Medicine and lead author on the study. “Given the aging population and the simplicity of increasing a person’s level of vitamin D, a small improvement in death rates could have a substantial impact on public health.”

Older adults are at high risk for vitamin D deficiency because their skin has less exposure to the sun due to more limited outdoor activities as well as reduced ability to make vitamin D.

The study analyzed data from the Third National Health and Nutrition Examination Survey conducted by the National Center for Health Statistics. The research team analyzed vitamin D in blood samples of more than 3,400 participants that were selected to be representative of the 24 million older adults in the United States. Compared to those with optimal vitamin D status, those with low vitamin D levels were 3 times more likely to die from heart disease and 2.5 times more likely to die from any cause.

Dr. Ginde says the findings suggest that current daily recommendations of vitamin D may not be enough for older adults to maintain optimal health. The research team has applied for research funding from the National Institutes of Health to perform a large, population-based clinical trial of vitamin D supplementation in older adults to see if it can improve survival and reduce the incidence of heart disease.

“Confirmation of these results in large randomized trials is critically important for advancing public health,” says Carlos Camargo, MD, DrPH, of the MGH Department of Emergency Medicine, the senior author of the study and an associate professor of medicine at Harvard Medical School.

The study looking at elderly death rates is the second of two studies by the same team of researchers on vitamin D and general health. The first study, published in Archives of Internal Medicine earlier this year, identified vitamin D as playing a significant role in boosting the immune system and warding off colds and flu.

“Vitamin D has health effects that go beyond strong bones,” says Ginde. “It’s likely that it makes a vital contribution to good health.”

via Insufficient levels of vitamin D puts elderly at increased risk of dying from heart disease.