London: It`s known that too much salt is bad for your heart. Now, a new study has found that it could also increase your risk of developing Alzheimer`s disease.
Researchers at the University of Toronto in Canada found that elderly people who have salt-rich diets and do little exercise suffer a quicker mental decline than those who are more prudent with their intake.
Worryingly, just over a teaspoon of salt a day could dull the mind and raise the risk of Alzheimer`s, they claimed.
For the study, the first to link salt consumption to the deterioration of brain health in the elderly, the researchers looked at the salt intake and levels of physical activity of 1,262 healthy men and women aged between 67 and 84 over a three-year period.
They also assessed their mental health at the start of
the study and once a year for the duration, using a battery of
tests more commonly used to diagnose Alzheimer`s.
"Our study showed that a diet high in sodium, combined with little exercise, was especially detrimental to the cognitive performance of older adults," said study author Dr Alexandra Fiocco.
"But the good news is that sedentary older adults showed no cognitive decline over the three years that we followed them if they had low sodium intake," Dr Fiocco said.
A high level was defined as more than 3,090mg of pure sodium a day, or just over a teaspoon of salt a day. This is the equivalent of 15 bags of crisps, three-and-a-half Big Macs or almost two full English breakfasts.
But some of those taking part in the study were eating almost three times this, the team reported in the journal Neurobiology of Ageing.
The researchers said that knowledge of the link between salt and declining brain power could help people age healthily.
"These findings are important because they help people know they can be proactive in retaining healthy brains as they age," said co-author Carol Greenwood, a professor at the University of Toronto.
"Baby Boomers especially need to know that sitting on the couch watching television for long periods of time and eating salty snacks is not good for them."
Deborah Barnes, a dementia expert at the University of California in San Francisco, said:
"This is one of the first studies that looks at sodium. It`s another important point about diet. You need to eat more fresh fruits and vegetables and stay away from processed foods."
According to the Food Standards Agency in the UK, adults should eat no more than 6gm of salt, or one teaspoon, per day.
Past research also suggested that people who reduce salt in their diet by about 3gm a day can reduce their chances of developing cardiovascular disease by a quarter.
A recent major review of the evidence on the dangers posed by salt created controversy by concluding that lowering consumption has little effect on health.
But other experts say that one in five strokes and heart attacks would be prevented if everyone just ate a third of a teaspoon less of salt a day.