CRUNCHING on just one bowl of your favourite cereal a day might raise your risk of dementia, research suggests.
Scientists have found a link between high levels of thiamine - a vitamin commonly added to breakfast cereals - and cognitive decline.
One in 10 people who experience mild cognitive impairment go on to develop dementia, according to .
Thiamine, also known as vitamin B1, helps turn food into energy and keep the nervous system healthy, the .
Your body doesn't make it by itself, but you can usually get all you need of the vitamin from your diet.
It's found naturally in some foods, added to others and sold in supplement form too.
Thiamine is often added to cereals like corn flakes and frosted flakes, as well as bread and baby formulas.
According to the , foods that commonly contain the vitamin are:
Research has previously linked a deficiency in thiamine to neurological problems like cognitive decline.
One form of thiamine deficiency is called Wernicke-Korsakoff syndrome and causes cognitive changes similar to Alzheimer’s disease.
Studies conducted on animals have suggested that a lack of thiamine may cause oxidative stress or the death of nerve cells, memory loss, formation of plaque, and reduced glucose metabolism, which are all risk factors for Alzheimer’s disease.
But research in humans has been limited.
Now, a new study published in the journal also linked higher thiamine intake to cognitive decline, especially in people who had high blood pressure or were obese.
Researchers at Anhui Medical University in Hefei, China, looked at data from the China Health and Nutrition Survey.
Some 3,000 adults, aged 63 on average, were asked to report their diets and repeat cognitive function tests - these included word recall and number pattern challenges.
As researchers followed up with participants after about five years, they found a link between thiamine consumption and a decline in cognitive test scores.
Too little or too much of thiamine can have adverse effects, but researchers pinpointed an ideal amount of thiamine between the two.
We speculate that high levels of dietary thiamine intake may lead to cognitive decline by inducing elevated levels of acetylcholine in the brain.
Anhui Medical University research team
On average, study participants consumed 0.93 mg per day.
Researchers' analysis found that the ideal amount was 0.68 mg per day, but between 0.6 mg and 1.00 mg per day had minimal risks.
However, every 1.0 mg per day above the safe limit of 0.68 mg was associated with a fall of 4.24 points in cognitive scores.
And an average bowl of most fortified breakfast cereals contains more than the sweet spot of 0.68 mg.
The National Institutes of Health report that one serving contains 1.2 mg of thiamine.
The study team wrote: "Beyond the inflection point of dietary thiamine intake, thiamine intake was significantly positively associated with cognitive decline.
"This finding is consistent with our recent studies, which found that long-term excessive intake of thiamine was associated with an increased risk of new-onset diabetes and new-onset hypertension in
the general population.
"This series of studies consistently shows that excessive intake of thiamine may have adverse health effects on Chinese adults."
They explained that thiamine can regulate levels of acetylcholine - a neurotransmitter that plays a role in memory, learning and attention - by inhibiting the activity of the enzyme cholinesterase.
"High levels of acetylcholine in the brain can adversely affect cognition," researchers said.
"Therefore, we speculate that high levels of dietary thiamine intake may lead to cognitive decline by inducing elevated levels of acetylcholine in the brain."
But they noted that more research is needed to confirm their results.
Researchers also noted that the link between thiamine intake and cognitive decline was stronger in individuals with hypertension - as high blood pressure is also known - and obesity.
"Hypertension and obesity are established risk factors for cognitive decline, which could impair cognitive function by affecting cerebrovascular structure and central inflammation, respectively," they said.
The study team said their findings emphasised the importance of avoiding excessive thiamine intake for people with high blood pressure or obesity.
WE all notice a natural decline in memory and thinking as we age.
This will be more pronounced in some people, as they experience memory and thinking problems that are mild but still noticeable.
This is described as mild cognitive impairment (MCI). Unlike dementia sufferers, people with MCI can still get on with day-to-day life.
Research suggests that two out of 10 people over the age
of 65 have MCI, according to Alzheimer's Research UK.
About one in 10 people who've received an MCI diagnosis will go on to develop dementia.
Symptoms of MCI include:
Memory - Misplacing items or having trouble
remembering recent conversations.
These symptoms may affect someone with MCI all the
time, or they might come and go.
There are steps we can take to keep our brains as healthy as possible. These include:
