Low vitamin D status associated with cognitive decline: Study

Inadequate dietary intake of vitamin D is associated with higher levels of cognitive impairment; however it remains unclear if the link is causal, according to a new study.

The study, published in Neurology, suggests that a weekly intake of less than 35 micrograms of vitamin D is associated with a greater incidence of cognitive impairment. However the researchers noted that the association could be causal in either direction, stating it is possible that low vitamin D is a result of, rather than the cause of cognitive impairment.

“The main finding of this population based study …was that the weekly dietary intake of vitamin D was significantly associated with the global cognitive performance in both linear and logistic regression models, even while considering the effects of all potential confounders,” said the researchers, led by Dr Cédric Annweiler from Angers University Hospital, France.

D and cognitive decline

Cognitive performance declines naturally as we age, but it has been suggested that vitamin D status could impact on cognitive function among older adults.

It is suggested that vitamin D binds to neuronal receptors in the brain, and develops an anti-neurodegenerative action through, anti-inflammatory and antioxidative. Many people have therefore recommended that maintaining an adequate vitamin D status is essential to avoid vitamin D deficiency– induced cognitive decline.

Data from David Llewellyn and colleagues at the University of Exeter, England, indicated that insufficient levels of vitamin D may accelerate cognitive decline . The scientists analyzed vitamin D levels from blood samples of 858 adults and found that severe vitamin D deficiency was associated with a 60 percent increase in the risk of substantial cognitive decline.

Annweiler and colleagues said the benefits of vitamin D intake in treating or preventing cognitive impairment remain unknown, adding that, to date no randomized controlled trials have explored the benefits of vitamin D supplementation to treat or prevent cognitive impairment.

But, before conducting such a trial, they said it would be of benefit to determine whether dietary, non-supplemented, intake of vitamin D could be associated with cognitive performance in older adults.

“We had the opportunity to examine the association between dietary intakes of vitamin D and global cognitive performance in a large representative community survey of older women,” said the researchers.

Study details

A total of 5,596 women, not taking vitamin D supplements were divided into 2 groups according to their baseline weekly staus: either inadequate (less than 35 micrograms per week) or recommended (more than 35 micrograms per week).

Compared to women with recommended weekly vitamin D dietary intakes, women with inadequate intakes were reported to have lower scores on the SPMSQ mental state questionnaire.

The researchers observed that inadequate intakes were more often associated with cognitive impairment, as defined by an SPMSQ score of less than 8.

“We found an association between weekly vitamin D dietary intake and SPMSQ score. Inadequate weekly vitamin D dietary intakes were also associated with cognitive impairment,” wrote the researchers.

Causation

Exactly how low dietary intakes of vitamin D and decreased cognitive performance are associated remains unclear. Annweiler and co workers noted that it is yet to be clarified whether the of association is causal, and if so, in what direction the causation may be.

They stated that it remains a possibility that low vitamin D status may be a result of poor diet, due to cognitive decline. But, emphasized that vitamin D insufficiency has been suggested as a contributing factor to hypertension, which itself is a major risk factor in the development of cerebrovascular diseases and cognitive decline.

Annweiler and colleagues added that nutrients are not consumed in isolation, “but rather as components of an overall diet, which is precisely considered as a modifiable risk factor for cognitive decline.”

Moreover, they said that as a component of diet, low vitamin D intake may be a surrogate measure for other nutritional abnormalities, which in turn may lead to cognitive decline.



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Milk Strike

Infant Feeding

Health experts say the best source of nutrients for a baby is breast milk. Breastfeeding has benefits for the baby and for mom. For the baby, breast milk contains the right amount of nutrients to support the infant’s growth and development. For the mom, breast milk is readily available (no mixing formula or heating bottles). Breastfeeding also provides a close bond between mom and baby.

The American Academy of Pediatrics recommends breastfeeding until a baby is at least six months old. Women who don’t breastfeed can use iron-fortified infant formula. At about four to six months, many infants can be introduced to baby cereals. Other baby foods are slowly offered starting around six months.

Milk is an important source of nutrition for children as they grow older. It provides calcium, vitamin D and minerals needed by the body. Whole milk is recommended for most children until they reach two because most children need the extra fat and calories. After two, parents can switch to low-fat or nonfat milk.

Experts warn parents should avoid giving cow’s milk until a child reaches his/her first birthday. Tyrala says cow’s milk is a great source of nutrition for calves, but not for humans. A baby’s digestive system can’t handle the extra protein in cow’s milk. Adding it too early to a child’s diet can cause liver and kidney damage and increase the risk for an allergic reaction.


Transition Troubles

Most children take the change from breast milk or formula to cow’s milk in stride. But sometimes babies become very fussy and don’t want to accept cow’s milk. Occasionally, a baby will refuse to drink cow’s milk and go on a “milk strike.”

Eileen Tyrala, M.D., Pediatrician at St. Christopher’s Hospital for Children in Philadelphia, says taste is probably the biggest obstacle for babies when parents try to transition to cow’s milk. Human milk and formulas are much sweeter than cow’s milk and there are differences in the thickness and temperature of the milks. For breastfed babies, the change to a bottle or cup can trigger a loss of bonding associated with breastfeeding.


Tyrala offers some tips for parents who are having trouble with infants on a “milk strike”:

•Offer cow’s milk in a sippy cup. This helps the baby make the association between the new drink and the different taste and texture.

•Go slowly. If the child is very resistant to the change, try just one serving of cow’s milk a day. Then gradually increase the number of servings of cow’s milk. It can take several days to two weeks for the child to reach the goal of drinking all cows’ milk.

•Dilute the familiar drink. Use three parts breast milk or formula to one part water. This will slightly alter the taste and texture of the “familiar” drink and, hopefully, enable the child to gradually accept a different drink (cow’s milk). Tyrala says it should only take a few days for a child to accept cow’s milk using this technique, so the temporary loss of calories won’t have any great affect on the infant.

•Add some low-sugar flavor. Tyrala doesn’t like the idea of adding sugar-laden flavorings to make cow’s milk as sweet as formula or breast milk. If taste appears to be an issue, she suggests adding powdered flavorings with less sugar.

•Try a substitute. Try an alternative to cow’s milk, like soy milk, rice milk or potato milk. Make sure these substitutes are pasteurized and are supplemented with calcium and vitamin D. If a child continues to refuse to drink cow’s milk, try yogurt, soft cheeses or calcium fortified orange juice.

If you have any specific questions or concerns about feeding your children, talk with your health care provider. For general information:

• American Academy of Pediatrics

• National Institute of Child Health and Human Development

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Vitamin D: A potential role in cardiovascular disease prevention

Inadequate levels of vitamin D are associated with an increase in the risk of cardiovascular disease and death, a new observational study has found. Dr Tami L Bair (Intermountain Medical Center, Murray, UT) reported the findings here at the American Heart Association 2009 Scientific Sessions.

Bair and colleagues followed more than 27 000 people 50 years or older with no history of cardiovascular disease for just over a year and found that those with very low levels of vitamin D (<15>30 ng/mL). Those deficient in vitamin D were also twice as likely to develop heart failure as those with normal levels.

"We concluded that even a moderate deficiency of vitamin D was associated with developing coronary artery disease, heart failure, stroke, and death," said coauthor Dr Heidi May (Intermountain Medical Center). However, "it is not known whether this is a cause and effect relationship," she told heartwire. Because this study was observational, more research is needed "to better establish the association between vitamin D deficiency and cardiovascular disease," she noted.


Evidence so far suggestive of benefit of vitamin D

Vitamin D was the subject of much discussion in a general session on vitamins at the AHA scientific sessions. Although the evidence supporting the benefits of vitamin D in cardiovascular disease is probably stronger than for any other vitamin, there have been only a few randomized clinical trials, and previous observational studies "show no robust effects," said Dr Harald Dobnig (Medical University of Graz, Austria). The latter suffer from limitations, such as doses of vitamin D supplementation that are too low, low compliance rates, and short study duration, he noted.

There are some large randomized trials underway looking at outcomes with vitamin D; it is hoped that they will provide definitive answers in five to seven years, Dr Eric Rimm (Harvard School of Public Health, Boston, MA) explained.

"I think there's promise for vitamin D. We know that most people have insufficient vitamin D levels in their blood," Rimm told heartwire. "So although it will take five years until some of the trials that are adequately powered to look at cardiovascular disease with vitamin D will report, the epidemiology right now is suggestive that people should have 1000 or 2000 IU of vitamin D a day," he said.


Vitamin D: How do we get it, and how much is enough?

Rimm discussed vitamin D at length, explaining that there are two sources: sunlight in the form of UVB rays, and diet (foods and supplementation). "Many tissue types and cells in the body have vitamin D receptors, and the active form of vitamin D is modulated by calcium and parathyroid hormone," he explained, with potential downstream effects on a number of bodily systems—inflammatory markers and the renin angiotensin system to name just two—he said.

People at highest risk of vitamin D deficiency include those with darker skin, those living at high altitudes, the elderly (because there is less of the precursor for vitamin D in the blood as people age and older people tend to spend less time outside), the obese, those who avoid the sun or cover the skin in the sun, those who are the immobilized or institutionalized, and pregnant and breast-feeding women.

Deficiency in vitamin D is generally agreed to be a blood level of <20>150 ng/mL indicating excessive vitamin D.

Data suggest that many people are likely getting inadequate vitamin D, he said, with studies showing that black Americans have blood levels ranging from 6-18 ng/mL and that white Americans have levels ranging from 16-25 ng/mL.

In general, a supplement of 100 IU of vitamin D per day will increase blood levels of vitamin D by 1 ng/mL, Rimm said. Those taking 1000 IU per day should have blood levels in the range of 25-32 ng/mL and those taking 4000 IU should have levels of 40-50 ng/mL.


Diet and sunshine good sources of vitamin D

However, Rimm stressed that vitamin D need not just come from supplements. "I think for vitamin D, it's a shame just to count on supplementation because, during the right times of year, five to 10 minutes a day of sunlight is sufficient is to make enough vitamin D. I do hear the concerns about skin cancer and I think people should wear suntan lotion, but it's probably better to put it on 10 minutes after you've been in the sun."

He cautioned that "in northern climes, even if you go out in the sun in January, you're not going to make much vitamin D, so there you would need supplementation to get adequate levels."
One of the best dietary sources of vitamin D is fish.

People should remember that diet is an important source of vitamin D, too, he noted. "One of the best dietary sources of vitamin D is fish. We already suggest people eat a couple of servings a week, but having three or four servings a week of fish can get you a fair bit of vitamin D, and would represent an additional 300 to 500 IU of vitamin D. This still might not be sufficient so you might need a little bit of sunlight or to take a vitamin D supplement. It's really a combination of things, that's probably the best approach."

Both Rimm and Dobnig said it is nearly impossible for anyone to suffer adverse effects from too much vitamin D. Those who spend whole days in the sun, such as lifeguards, have vitamin D levels ranging from 45 to 65 ng/mL, said Rimm. "Vitamin D is safe. Hypercalcemia is not a problem, with the rare exception of granulomatous disease," said Dobnig. He added that because vitamin D is a fat-soluble vitamin, it can be given weekly, or even monthly.


Results of two large randomized trials eagerly awaited

Rimm said he hopes ongoing research will inform the vitamin D debate. Data are needed on intermediate end points, such as inflammatory markers and parathyroid hormone, and on "hard" end points, such as coronary artery disease, sudden death, and heart failure, both in primary prevention and in high-risk populations, including those with chronic kidney disease and heart failure.

The results of two large randomized trials are eagerly awaited, he said, including the National Institutes of Health-sponsored VITAL study looking at whether 2000 IU vitamin D and/or 1 g of fish oil (omega-3 fatty-acid supplementation) can reduce the risk of developing heart disease, stroke, or cancer in 20 000 men and women, which is slated to begin in January 2010.

The Thiazolidinedione Intervention with Vitamin D Evaluation (TIDE) study is being coordinated by researchers at McMaster University, Hamilton, ON. This trial is looking at rosiglitazone versus pioglitazone in people with type 2 diabetes at risk of heart disease, but also has a vitamin D versus placebo arm. The primary outcome for the vitamin D arm will be cancer, but there are a number of secondary cardiovascular end points, said Dobnig. Right now, I think the evidence for vitamin D probably is stronger than the evidence for other vitamins.

"The evidence for vitamins is not great," Rimm said. "The best thing we can say now is to stop smoking, eat a good diet, and don't be overweight. I think people sometimes lose touch with the most important message of prevention, and jump right to the vitamins thinking that's going to sustain them, so doing what we know first and best is probably the best place to start."

"After that, right now, I think the evidence for vitamin D probably is stronger than the evidence for other vitamins," he concluded.



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Study Suggest Vitamin D Levels Too Low for 1 in 5 U.S. Children, Daily Dose is 4 cups of milk

1 in 5 kids get little vitamin D, study says....

At least one in five U.S. children aged 1 to 11 don’t get enough vitamin D and could be at risk for a variety of health problems including weak bones, the most recent national analysis suggests.

By a looser measure, almost 90 percent of black children that age and 80 percent of Hispanic kids could be vitamin D deficient — “astounding numbers” that should serve as a call to action, said Dr. Jonathan Mansbach, lead author of the new analysis and a researcher at Harvard Medical School and Children’s Hospital in Boston.

The findings add to mounting evidence about vitamin D deficiency in children, teens and adults, a concern because of recent studies suggesting the vitamin might help prevent serious diseases, including infections, diabetes and even some cancers.

While hard evidence showing that low levels of vitamin D lead to disease or that high levels prevent it is lacking, it’s a burgeoning area of research.

Exactly how much vitamin D children and adults should get, and defining when they are deficient, is under debate. Doctors use different definitions, and many are waiting for guidance expected in an Institute of Medicine report on vitamin D due next year. The institute is a government advisory group that sets dietary standards.

The new analysis, released online Monday by the journal Pediatrics, is the first assessment of varying vitamin D levels in children aged 1 through 11.

Previous studies in the journal this year found low levels were prevalent in U.S. teens, and also showed kids with low levels had higher blood pressure and cholesterol levels, and were more likely to be overweight.

The new analysis uses data from a 2001-06 government health survey of nearly 3,000 children. They had blood tests measuring vitamin D levels.

Using the American Academy of Pediatrics’ cutoff for healthy vitamin D levels, 6.4 million children — about 20 percent of kids that age — have blood levels that are too low. Applying a less strict, higher cutoff, two-thirds of children that age, including 90 percent of black kids and 80 percent of Hispanics, are deficient in vitamin D.

A Pediatrics editorial says the strongest evidence about effects of vitamin D deficiency in kids involves rickets, a bone disease common a century ago but that continues to occur.

Rickets can be treated and prevented with 400 units daily of vitamin D, the editorial says. The pediatricians’ group recently recommended that amount for all children, saying that most need vitamin supplements.

Mansbach says his study, funded by the National Institutes of Health, supports that recommendation.

Children can get 400 units daily by drinking four cups of fortified milk, or eating lots of fish, but many don’t do that.

The body also makes vitamin D when sunlight hits the skin, but many children don’t spend enough time outdoors. That’s one reason why lower vitamin D levels are found in children living in colder climates and those with darker skin, which absorbs less sunlight.



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CDC Targets Vitamin D in Preventing Childhood Asthma

The Center for Disease Control and Prevention has identified asthma as the most common chronic childhood illness. A five-year research study has been launched among pregnant women to determine whether Vitamin D supplements will prevent children from developing asthma. The Vitamin D Antenatal Asthma Reduction Trial (VDARRT) is funded by the National Institutes of Health.

According to recent studies, Vitamin D plays some role in developing an infant’s lungs during the later part of pregnancy. Children have an increased risk of beig born with asthma if one or both parents have asthma. Researchers want to determine if the correction of Vitamin D levels prior to or during the pregnancy will lower the rates of asthma in children.

Recent studies have shown that fortification of food and multivitamin intake has not prevented Vitamin D deficiency in children and adults. Although most pregnant women take prenatal vitamins, pregnant women are at high risk for Vitamin D deficiency. That risk extends to lactating women and the children they breastfeed.

The lead investigator of the trial, Robert C. Strunk, M.D., wants to know if simply supplementing Vitamin D during pregnancy could impact children’s health by decreasing the prevalence of asthma. Dr. Strunk is a Washington University pediatric asthma and allergy specialist at St. Louis Children’s Hospital.

The study targets 870 women nationwide between 10-18 weeks of pregnancy. The women will be randomly divided into groups. One group will receive a standard prenatal vitamin containing 400 units of Vitamin D while the other group will receive the same prenatal vitamin and a 4,000-unit vitamin D supplement. Participants will continue regular obstretrician visits. Blood and urine samples will be collected, and questionnaires will be completed concerning diet, sunlight exposure, medications and other matters. The children born will be evaluated at ages 1, 2, and 3 for asthma signs and recurrent wheezing.

Members of the collaborating team on this project include Washington University School of Medicine in St. Louis, Boston University and Brigham and Women’s Hospital in Boston, as well as Kaiser Permanente Medical Center, located in San Diego.



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