Regularly eating a lot of hot peppers may increase a person's risk of cognitive decline.
Many populations around the world add spicy peppers to their local dishes to enhance the taste and make for a more punchy culinary experience.
But are spicy peppers healthful, or do they pose any health risks? The spiciest peppers in the world, such as the Carolina Reaper, could cause serious, immediate damage.
However, most people will not reach for the extreme versions of this hot vegetable. Instead, most cuisines use much milder varieties — some of which are still very spicy — such as jalapeños, cherry peppers, cayenne peppers, Scotch bonnets, and habaneros.
Previous research into the potential effects of chili peppers on health has generally had positive findings. A large cohort study from 2017, for instance, found that eating hot red chili peppers was associated with lower mortality risk.
The main active ingredient in hot peppers, and the one that makes them spicy, is capsaicin, so it is most likely that this compound plays a lead role in hot peppers' potential effect on health.
In spite of encouraging findings about the association between chili peppers and mortality, no studies in humans had seriously evaluated how these hot vegetables might affect cognitive decline.
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Now, the findings of a longitudinal cohort study in a large Chinese population suggest that consistently eating a large amount of chili pepper could hasten cognitive decline, increasing a person's dementia risk.
The research — presented in a study paper that features in the journal Nutrients — involved 4,582 Chinese participants aged over 55. The research team was led by Zumin Shi, Ph.D., from Qatar University, in Doha.
Higher risk at over 50 grams of chili per day
"Chili consumption was found to be beneficial for body weight and blood pressure in our previous studies. However, in this study, we found adverse effects on cognition among older adults," notes Zumin.
The researchers found that people who ate more than 50 grams of chili per day on a regular basis had almost twice the risk of cognitive decline of people who ate less than this amount of chili.
"Derived from dietary surveys, chili intake included both fresh and dried chili peppers, but did not include sweet capsicum or black pepper," the researchers mention in their study paper.
The team also noted that participants who generally ate a greater amount of chili tended to have a lower financial income, as well as a lower body mass index (BMI). But they engaged in more physical activity, compared with people who ate a smaller amount of chili pepper, and the intake of fats was similar between the two groups.
The investigators suggest that people with a healthy BMI may have a more heightened sensitivity to capsaicin than those who are clinically overweight. The heightened sensitivity, the team adds, may also explain why these people may have a higher risk of cognitive decline.
Zumin and colleagues also saw that people who ate more chili tended to be younger than people who did not eat chili. "Furthermore," the researchers write, "there was no association between chili consumption and BMI or hypertension in this population, and therefore, it is possible that older people in this population avoided chili consumption due to chronic disease."
Another factor that seemed to play a role in how much chili participants ate was their education level. In the conclusion to the study paper, the researchers note:
"In our study, there was a significant difference in chili intake among people with different education levels. Therefore, it is possible that the confounding effect of education may still contribute to the relationship between chili intake and cognitive function."
For this reason, the investigators suggest that further trials should aim to assess the link between education level, chili intake, and the risk of cognitive decline.