Why eating too much chilli could lead to memory loss

One of the world’s most commonly used spices, chilli, may result in memory loss if you eat too much of it, according to a new study.

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Chilli lovers who can’t get enough of the hot tingle produced by their favourite spicy foods should proceed with caution.

Although chilli is thought to be effective in battling obesity and hypertension, a new study involving University of South Australia (UniSA) shows that a spicy diet rich in chillies could be linked to memory decline.

The 15 year-study, published in the journal Nutrients this week, examined the dietary habits and cognitive capacities of almost 5,000 Chinese adults aged between 55 and 71 to determine the impact of long-term chilli consumption on memory. 

After running several cognition tests and evaluating participants' diet, BMI and socioeconomic status, researchers saw that people who ate the most chillies, daily, experienced the biggest drop in memory quality.

In fact, these chilli-loving seniors had almost double the risk of self-reported poor memory and memory decline.

The research, led by Dr Zumin Shi from Qatar University, found that adults aged over 55 who ate consistently more than 50 grams (around 3.5 tablespoons) of chilli a day showed evidence of faster cognitive decline. In fact, these chilli-loving seniors had almost double the risk of self-reported poor memory and memory decline.

“The prevalence of self-reported poor memory and memory decline increased with the increase of chilli intake,” the study reads.  

Chilli intake as defined by the study included both fresh and dried chilli peppers but not sweet capsicum or black pepper.

BMI, chilli intake and your memory

Capsaicin is the active component in chilli that gives it its intense heat. To-date it’s been reported that this pigment speeds up metabolism, fat loss and inhibits vascular disorders. But this study is the first to discover an association between chilli intake and cognitive function.

“Whenever we are looking at blood pressure or diabetes or cognition function, what we do know as a general rule is that we can’t eat all foods as much as possible and [be unaffected],” says UniSA epidemiologist Dr Ming Li, who was involved in the study.

“All foods can be beneficial in the right quantities and too much of any food can be poison.”

The study also revealed a positive association between chilli intake and cognitive decline, which was stronger among those with a low BMI. On the flip side, many Chinese adults with obesity did not eat as much chilli or suffer such a decline in their memory.

“Participants with a high chilli consumption had a lower income and BMI, and were more physically active compared with non-consumers,” the study reads.

All foods can be beneficial in the right quantities and too much of any food can be poison.

No matter where you're from, eating chilli in excess may be a problem

Although chilli is believed to have originated from South America, the spice is now used in cuisines all across the world from China to India and Spain to the USA.

Due to the widespread popularity of chilli, Dr Li expects the research results to hold true for all adults who eat a lot of the ingredient - not just Chinese adults.

“In this study, we quantify that if chilli intake is more than 50 grams a day, it’s associated with a cognitive poor cognition function," she says. "So the impact of eating chilli depends on the chilli intake and the amount consumed.”

As Chinese culture dictates, chilli is used heavily in various regional cuisines.

“In certain regions of China such as Sichuan and Hunan, almost one in three adults consume spicy food, including chilli, daily,” the study reads. “Among the chilli consumers [in the Chinese study], about 30 per cent had chilli intake above 50 g per day.”

One thing we think [it might be] is that capsaicin may be neurotoxic if too much is consumed.

Although the mechanism behind the association between chilli and cognitive function is not clear, Dr Li says one hypothesis relates to toxicity in the brain.

“One thing we think [it might be] is that capsaicin may be neurotoxic if too much is consumed,” explains Dr Li.

“…Generally, we should always aim to have a balanced diet that includes all kinds of foods combined.”

The study observed an association and did not prove cause and effect. More research is needed to understand the link between chilli intake and cognitive function.