"There is accumulating evidence from mostly experimental research to show the benefit of spices or their active components on human health," said Lu Qi, an associate professor at Harvard School of Public Health and co-author of the study published this week in the BMJ. But the evidence evaluating consumption of spicy foods and mortality from population studies was lacking, he said.
As a result, researchers from the Chinese Academy of Medical Sciences studied data collected from 2004 to 2008 as part of the China Kadoorie Biobank. Using self-reported questionnaires, they analyzed the spicy food consumption of nearly half a million people age 30 to 70 across 10 regions in China, excluding those with cancer, heart disease and stroke.
They then reviewed the records of 20,224 people who died over a seven-year followup period and found that those who ate spicy foods six or seven times a week had a 14% lower risk of premature death for all causes than people who ate spicy foods less than once a week. People who frequently consumed spicy food also showed a lower risk of death from cancer or ischemic heart and respiratory system diseases.
Fresh and dried chili peppers were the most common spicy sources, according to the study.
What is it about spicy foods? The study points to the benefits of capsaicin, a bioactive ingredient in chili peppers, which has been linked to health perks such as increased fat burning. Folk medicine practitioners also say capsaicin can help fight infection and stimulate the kidneys, lungs and heart.
The new research found an "association" between death and spicy food consumption, but an editorial published with the study cautions that this is not definitive. As a result, experts emphasize the need for more research before a connection between these ingredients can be scientifically established.
"It's an observational study within a single culture," said Daphne Miller, associate clinical professor at the University of California, San Francisco and author of "The Jungle Effect: The Healthiest Diets from Around the World, Why They Work and How to Make Them Work for You."
There are many variables associated with eating spicy food that haven't been accounted for, she said. The study itself cites limitations including the lack of information about other dietary and lifestyle habits or how spicy food was cooked or prepared. In addition, researchers note that although chili pepper was the most commonly used spice based on self-reports, the use of different spices tends to increase as the use of chili pepper increases. Consuming these other spices may also result in health benefits, independent of chilies.
However, Miller said the findings are still plausible, given the fact that spicy foods also have high levels of phenolic content, which are chemicals with nutritional and anti-inflammatory values.
Bio-psychologist John E. Hayes agrees. The fact that there seems to be an overall protective effect in chili intake is especially interesting, according to Hayes, an associate professor of food science and director of Sensory Evaluation Center at Penn State University. He has previously studied spicy food and personality association.
Now, scientists need to figure out why this benefit is occurring.
Hayes pointed out one significant question: "Is it a biological mechanism or a behavioral mechanism?"
A biological connection could mean that when you eat spicy food, thermogenesis occurs, increasing the basil metabolic rate, said Hayes, while a behavior mechanism could be that eating spicy food slows food intake, causing a person to eat fewer calories. A lower calorie consumption could indicate a more healthful diet, which would be an unaccounted variable not shown by the new study.
Qi, the author of this new study, believes the protective effect associated with spicy foods would indeed translate across cultures, but Hayes cautioned care.
"It's a very big study, a very controlled study," he said, that may not generalize to other countries. For instance, in the U.S., "spicy food is ubiquitously available but not ubiquitously consumed."
"You have to consider that when we talk about spicy food, we can mean vastly different things, with different health implications," Hayes said. "That spicy food could be low-energy-density vegetables, like kimchee. Or it could be a high-energy-density food like barbecue spare ribs."
So before you make a run for the hot sauce, more research is needed to qualify what spicy entails and the various ingredients, which the current study does not break down.
"This isn't an excuse to go out and eat 24 wings and then rationalize it by claiming they are going to make you live longer," Hayes said. "When you're looking at a whole food versus the individual component, we have to be very cautious."
This is the big caveat. "In science, we try to break things down into the simplest parts while still considering the context," Hayes said.
- Credit: Liza Lucas/CNN
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