vitamin D

Kids’ Vitamins Often Exceed Recommended Doses

Young children who take vitamins may be consuming much greater levels than recommended of the nutrients, a new study suggests.

For the research, scientists reviewed the labels of nearly 200 dietary supplements marketed for children in two age groups: younger than 12 months, and 1 to 4 years old. The researchers determined the level of vitamins that children would consume if they used the product as directed. (Specifically, they looked at levels of vitamins A, C, D, E, K and B12, along with thiamin, riboflavin, niacin, folate, biotin and choline.)

Most products contained vitamin levels much greater than those recommended for children in a single day. For example, dietary supplements for children ages 1 to 4 contained, on average, about 300 percent of the daily recommended levels of vitamin A, thiamin and riboflavin, 500 percent of the recommended level of vitamin C and more than 900 percent of the recommended level of biotin

Vitamin D was the only vitamin that was present at or below recommended levels for both age groups.

It’s too soon to know whether these findings are concerning, said study researcher Michael Madden, an assistant professor at Lake Erie College of Osteopathic Medicine (LECOM) School of Pharmacy. That’s because few studies have explored the effects of greater-than-recommended levels of vitamins on infants and young children. So in many cases, the maximum amount of a vitamin that’s safe for a child to take is not known, the researchers said.

For this reason, the Institute of Medicine (IOM) recommends that young children not consume excess levels of certain vitamins, including vitamins K and B12, thiamin, riboflavin, folate, pantothenic acid and biotin. (Infants should not consume excess levels of most vitamins.) The IOM, part of the U.S. National Academies, is a national nonprofit that advised the nation on health.

There is also a concern that children’s bodies may lack the ability to handle excess amounts of certain vitamins, the IOM says.

The findings suggests that “much of the pediatric vitamin supplementation is not based on IOM recommendations and therefore represents wholesale over-supplementation,” the researchers wrote in the Jan. 27 issue of the journal JAMA Pediatrics.

Some studies have also shown that dietary supplements may contain levels of vitamins that are different from what’s listed on the label.

The American Academy of Pediatrics (AAP) says parents should speak with their pediatricians about whether their young child may need to take supplements. Toddlers who eat a balanced diet should be getting adequate levels of most vitamins and so should not need supplements, the AAP says. And very high doses of some vitamins, such as vitamin A, may even pose risks because they can accumulate in the body, the AAP says.

But some children may need supplements if, for instance, they have selective eating habits, and therefore don’t get adequate levels of vitamins through food, the AAP says.

In addition, the AAP recommends vitamin D supplements for infants, children and adolescents so that they consume 400 International Units (IU) of vitamin D per day.

Source: live science

Milk Drinking Still a Mystery

The mutation for milk-drinking evolved independently in different parts of the world over the last 10,000 years as a result of strong natural selection, but why was it so advantageous?

Among the more momentous developments in human evolution was the ability to digest milk beyond early childhood.

Milk: Does It Really Do A Body Good?
Add it to the list of things that are bad for you: milk!
Mutations that enabled lifelong milk drinking appeared independently in several parts of the world over the last 7,500 years, according to growing evidence. And those genes spread rapidly. Today, about a third of adults around the world can drink milk without stomach problems, a trait known as lactase persistence.

But why was milk drinking so advantageous to humankind?

A new study debunks one leading theory: that milk provided a valuable source of vitamin D, which would’ve helped people absorb its calcium.

Newly analyzed human skeletons from an ancient site in Spain show that the milk-drinking gene spread just as rapidly in that sun-drenched climate as it did in other places, suggesting that milk must have been beneficial there for some reason other than its vitamin D content.

“Throughout the years, I have heard so many evolutionary hypotheses about lactase persistence because they are so fun to coin,” said Oddný Sverrisdóttir, an evolutionary biologist at the University of Uppsala in Sweden. “For decades now, people have hypothesized that it was because of lack of sunlight in the north of Europe that people would have had to supplement the lack of calcium and vitamin D by drinking milk.”

“Now, looking at this picture from Spain,” she said, “the calcium-assimilation hypothesis either didn’t affect the evolution of lactase persistence at all, or other forces were there as well.”

Sverrisdóttir has long been interested in how and why Europe’s early farmers began drinking milk, so she was excited when she got her hands on well-preserved samples of skeletal remains from eight people who lived in northeastern Spain about 5,000 years ago. That was well after the milk-drinking mutation had appeared in northern Europe, and she was eager to find out if those ancient Spaniards were drinking milk, too. So the first thing she did was test their DNA for lactase persistence.

“I thought at least one would have the mutation,” since so many of today’s Spanish adults can drink milk without health consequences, Sverrisdóttir said. “None did.”

To figure out whether the recent and rapid spread of lactase persistence in Spain was a fluke or if natural selection was at play, Sverrisdóttir and colleagues compared the mitochondrial DNA of modern Spaniards with the ancient samples. Mitochondrial DNA changes very slowly, making it ideal for tracing family trees over time.

And, the researchers report today in the journal Molecular Biology and Evolution, analyses showed that the ancient cave dwellers were indeed ancestors of people who live and frequently drink milk in Spain today.

Source; discovery news

How vitamin D controls blood pressure

A research team has decrypted the one of the biological mechanisms about Vitamin D deficiency triggering a range of diseases.

Vitamin D regulates the elasticity of blood vessels and thus also affects blood pressure amplitude.

The two primary authors, molecular biologist Olena Andrukhova and medical doctor Svetlana Slavic, of the Institute of Physiology, Pathophysiology and Biophysics at the Vetmeduni Vienna, found that prolonged vitamin D deficiency can stiffen blood vessels.

Examining the aorta, an elastic blood vessel that expands with each pulse of blood and then constricts again, the researchers showed that vitamin D deficiency makes the vessel less flexible.

Andrukhova explained that Vitamin D enhances the production of the enzyme eNOS (endothelial nitric oxide synthase) in the inner layer of blood vessels, the endothelium. This is critical for the regulation of blood pressure.

She said that the enzyme produces a molecule called nitric oxide (NO), an important factor for the relaxation of smooth muscles in the blood vessels.

Andrukhova explained added that when too little NO is formed, the vessels become less flexible, which ultimately leads to higher blood pressure which can give rise to other circulatory diseases, asserting that indirectly, vitamin D controls blood pressure.

The results have been published in the journal Molecular Endocrinology.

Source: sify

Vitamin D Deficiency Linked to Brain Damage, Says Study

A recent study, published by researchers from the University of Kentucky, in the journal Free Radical Biology and Medicine, suggests that low levels of vitamin D may cause brain damage.

Vitamin D is a fat-soluble vitamin present in few natural foods, including fatty fish, cheese and egg yolks; a variety of foods, meanwhile, are artificially fortified with vitamin D, including milk, cereals and margarine. Vitamin D manufacture can also be achieved endogenously, when rays of light strike the skin. This photochemical process triggers the production of vitamin D3 (a.k.a. cholecalciferol) from its precursor, 7-dehydrocholesterol.

Vitamin D confers a number of benefits, ranging from promotion of calcium absorption in the gut, maintaining serum calcium and phosphate levels, as well as bone growth and remodeling. On top of this, vitamin D regulates a number of genes that are involved in cell division, differentiation and an essential form of programmed cellular death (apoptosis). It is thought that vitamin D serves a variety of roles in inflammatory processes and could even serve neuromuscular and immune functions.

The Rat Research Models
The latest scientific research suggests that the vitamin may serve a critical role in protecting the brain from free radical-induced damage. The researchers used a series of rat models to test the influence of differing concentrations of dietary vitamin D. A total of 27 male rats were divided into three separate groups; one group was fed a diet that contained low concentrations of vitamin D (100 IU/kg food), another was used as a control (1000 IU/kg food) and the final group received a diet enriched in the vitamin (10,000 IU/kg food).

The trial began as the rats hit middle-age and lasted for a period of four to five months. The research group measured the level of oxidative and nitrosative stress in a specific part of the rat brains, located in the posterior cortex.

Intriguingly, the group found an elevation in the level of a reactive nitrogen species, called 3-nitrotyrosine, in those rats that had received inadequate levels of vitamin D. Nitrotyrosine is considered a marker of cellular damage and inflammation and has been found to be elevated in a number of pathologies, including inflammatory diseases, lung disease, sepsis and atherosclerosis.

The researchers believe that the increase in nitrotyrosine is caused by disruption of a protein complex (NF-?B) that is recruited during cellular stress. In addition, after performing redox proteomics, a number of proteins in this region of the brain were found to be damaged in those rats that were provisioned low vitamin D diets.

When examining the real-world affect that this vitamin D deficiency had on the rats, the research team established that subjects provided with an abundance of the sunshine vitamin excelled in cognitive performance tests. Specifically, when investigating learning and memory capacity, rats given diets consisting of 100 IU/kg of food were found to lag behind the other two groups, significantly.

The Future
Allan Butterfield was the lead author of the latest study, who works as a professor in the UK Department of Chemistry and as the director of the Center of Membrane Sciences, faculty of Sanders-Brown Center on Aging. Also acting as the director of the Free Radical Biology in Cancer Core of the Markey Cancer Center, Butterfield briefly discussed his research endeavors and what they could mean for elderly populations.

“Given that vitamin D deficiency is especially widespread among the elderly, we investigated how during aging from middle-age to old-age how low vitamin D affected the oxidative the oxidative status of the brain… Adequate vitamin D serum levels are necessary to prevent free radical damage to the brain and subsequent deleterious consequences.”
This problem is exacerbated in developing countries, where food nutrition is problematic. Likewise, individuals that inhabit regions that receive little sunlight and those who work indoors for long periods are also prone to deficiency, as are elderly people who lead sedentary lifestyles.

In the past, prior scientific studies have implicated hypovitaminosis D in Alzheimer’s disease, with a number of researchers suggesting its use as a biomarker of disease progression. A recent study, published in the Journal of Alzheimer’s Disease, entitled Low serum vitamin D concentrations in Alzheimer’s disease: a systematic review and meta-analysis, found there to be low serum vitamin D levels in Alzheimer’s patients, relative to controls.

Meanwhile, a study produced by Lu’o’ng and Nguyen, which explored the beneficial role of vitamin D in Alzheimer’s patients, found that its absence could trigger mood problems and cognitive impairment. They also point to evidence that links vitamin D deficiency to a number of proteins that are adversely affected in Alzheimer’s disease pathology.

Aside from neurological disease, a number of studies have linked deficiency of the vitamin to the development of cancers and cardiovascular pathologies. Osteomalacia and rickets, witnessed in adults and children, respectively, are commonly documented complications of vitamin D deficiency, causing softening and bowing of bones.

In concluding, Butterfield recommends people consult their general practitioners to determine their vitamin D levels, eat food enriched in vitamin D and get a minimum of 10 to 15 minutes of sun exposure every day; he also suggests individuals prone to deficiency should ask their doctor for advice about taking vitamin D supplements.

Source: Guardian express