The study authors point out that brain lesions of various sizes are not uncommon, even among healthy elders. However, the observation that the overall amount of brain matter affected by lesions goes up with vitamin intake is fuelling concerns about a possible connection.

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The first to examine the relationship
"This is one of the first studies to examine the relationship between diet and brain lesions," said study author Martha Payne, an assistant professor in the department of psychiatry and behavioural sciences with the Neuropsychiatric Imaging Research Laboratory at Duke University, North Carolina.

"Since our study only looked at diet and brain lesions at one point in time, we cannot conclude that calcium or vitamin D caused the brain lesions that we found," she cautioned. But she added that "our finding of a relationship between brain lesions and consumption of both calcium and vitamin D raises the question about a possible downside to high intakes of these nutrients."

However, one nutritionist said it's still far too early to warn people away from calcium and vitamin D, which is vital to bone health. "In general, the problem is that people don't have enough intake of vitamin D and calcium, not too much," said Susan Harris, a nutritional epidemiologist and scientist at the US Department of Agriculture Nutrition Center at Tufts University, in Boston.

Payne's team released its results Tuesday as part of an American Society for Nutrition presentation at the Experimental Biology 2007 meeting, in Washington D.C.

Higher intake recommended
The researchers conducted their work against the backdrop of public health messages that urge older people to take in calcium and vitamin D to ward off bone loss.

The authors note that calcium is also known to be important to proper nerve and muscle cell function.

According to the US National Osteoporosis Foundation, vitamin D3 and calcium deficiency is a global problem. The organisation's most recent scientific statement recommends that adults over the age of 50 consume 1 200mg of calcium daily. A daily total of 800 to 1 000 IU of vitamin D3 is also suggested, although the foundation cautions that supplementation at that level should only be taken with a doctor's supervision.

In addition to ingesting it in supplement form, calcium can be found naturally in milk, cheese and broccoli, and is often added to fortify foods such as orange juice, cereals and breakfast bars.

Vitamin D, key to good calcium absorption, is produced by the skin following exposure to the sun, although production decreases with age. Vitamin D is also found in foods such as saltwater fish, liver and dairy products.

Payne's current work follows her earlier exploration into a similar association between large brain lesions and high intake of high-fat dairy products.

Having ruled out fat as the link between diet and lesions, Payne shifted her analysis towards calcium and vitamin D.

How the research was done
The researchers looked at MRI brain scans from 232 men and women, aged 60 to 86, all of whom showed brain lesions of varying sizes.

The scans were taken as part of a larger study on late-life depression. As a result, nearly half the participants were diagnosed with depression.

In addition to mental health status, vitamin D and calcium intake habits were noted along with age and blood pressure readings.

The researchers found that, even after accounting for all other mitigating factors, a "strong relationship" seemed to exist between total lesion volume and vitamin D and calcium consumption.

Excess absorption of calcium
Payne and her associates believe the link may lie in an excess absorption of calcium by blood vessel walls. These could form bone-like deposits that narrow blood vessels and restrict elasticity. Excess vitamin D might exacerbate that process, they added.

In turn, blood vessel damage, if it were to occur in the brain, could lead to the development of brain lesions, they theorised.

Given that "higher intakes of calcium and vitamin D have been promoted in recent years as a way to prevent bone loss with ageing", Payne said that more in-depth study is urgently needed to further test such possible explanations for the observed vitamin-lesion link.

But Harris said that no one should be unduly alarmed by the current findings, at least for the time being.

"You wouldn't want to change your intake of calcium and vitamin D based on this study," she advised. "It may generate some hypotheses that are worth testing, but at this point the research can't really speak to whether the brain lesions were related to the calcium, vitamin D, or some other factor that people with high intakes of calcium and vitamin D also have." - (HealthDayNews, April 2007)

Read more:
Calcium, vit. D thwarts cholesterol
Colorectal cancer: calcium protects

 

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