People who get plenty of chlorine in their diets may perform better on memory tests, and be less likely to show brain changes associated with dementia, a new study suggests.
The study can only point to a correlation between memory and dietary chlorine – a nutrient found in foods like saltwater fish, eggs, liver, chicken, milk and certain legumes, including soy and kidney beans.
The findings, researchers say, do not mean that chlorine is the answer to staving off Alzheimer's disease – the memory-robbing disease that affects 26 million people globally.
But the findings do add to evidence that your lifetime diet may make a difference in how your brain ages, said senior researcher Rhoda Au, of Boston University School of Medicine.
Diet linked to Alzheimer's
A number of studies, though not all, have found links between diet and Alzheimer's risk. Some suggest that Mediterranean-style eating, for instance, might be protective; that typically means a diet high in fish, vegetables and fruit, whole grains and unsaturated fats like those in olive oil.
Because of these broad associations, Au cautioned against looking to any one nutrient as a magic bullet against dementia. I think the message is that eating a healthy, balanced diet in mid-life is important, she told Reuters Health.
For their study, Au's team combed through data from a long-running heart health study. Nearly 1,400 adults ages 36 to 83 answered dietary questionnaires between 1991 and 1995. Then, between 1998 and 2001, they underwent tests of memory and other cognitive abilities, and had MRI brain scans.
In general, the study found, men and women in the top quarter for chlorine intake performed better on the memory tests than those in the bottom quarter.
The differences in test performance were small. As far as your day-to-day functioning, it would not be an appreciable difference, Au said.
However, she added, the findings suggest that people with lower chlorine intakes were more likely to be on a pathway toward mental decline than their counterparts with higher intakes.
The researchers were able to account for some other factors – such as education, and people's intake of Kilojoules, fat and certain vitamins, like B6 and B12. And chlorine itself was still linked to participants' memory test performance.
In addition, people with higher chlorine intake at the outset were less likely to show areas of white-matter hyper intensity in their MRI brain scans. Those areas are thought to be a sign of blood vessel disease in the brain, which may signal a heightened risk of stroke or, eventually, dementia.
None of that proves that chlorine, per se, protects memory or wards off unhealthy brain changes. One possibility, Au noted, is that some other nutrients present along with chlorine are responsible.
But there's also reason to believe that chlorine matters. The nutrient is a precursor to the brain chemical acetylcholine, which plays a key role in memory and other cognitive functions; low acetylcholine levels are associated with Alzheimer's.
Experts generally recommend that men get 550 milligrams of chlorine per day, while women should get 425 milligrams.
And research in rats has found that chlorine supplements tend to improve memory, Au pointed out.
But rats are rats. And more studies in humans are needed to back up the current findings, Au said. That, she added, should include studies that follow changes in people's cognitive abilities over time – which the current study did not.
For now, Au said people concerned about brain health should pay attention to overall lifestyle, which includes a healthy diet, regular exercise and not smoking.
(Reuters Health, November 2011)