Scientists have reported the latest evidence that chilli peppers are a heart-healthy food with potential to protect against the number one cause of death in the developed world. The report was part of the 243rd National Meeting and Exposition of the American Chemical Society (ACS), the world's largest scientific society.
The study focused on capsaicin and its fiery-hot relatives, a piquant family of substances termed "capsaicinoids." The stuff that gives cayennes, jalapenos, habaneros and other chilli peppers their heat, capsaicin already has an established role in medicine in rub-on-the-skin creams to treat arthritis and certain forms of pain.
How capsaicin boosts heart health
Past research suggested that spicing food with chillies can lower blood pressure in people with that condition, reduce blood cholesterol and ease the tendency for dangerous blood clots to form.
"Our research has reinforced and expanded knowledge about how these substances in chillies work in improving heart health," said Zhen-Yu Chen, Ph.D., who presented the study. "We now have a clearer and more detailed portrait of their innermost effects on genes and other mechanisms that influence cholesterol and the health of blood vessels. It is among the first research to provide that information."
The team found, for instance, that capsaicin and a close chemical relative boost heart health in two ways. They lower cholesterol levels by reducing accumulation of cholesterol in the body and increasing its breakdown and excretion in the faeces. They also block action of a gene that makes arteries contract, restricting the flow of blood to the heart and other organs. The blocking action allows more blood to flow through blood vessels.
Capsaicinoids beneficial to heart
"We concluded that capsaicinoids were beneficial in improving a range of factors related to heart and blood vessel health," said Chen, a professor of food and nutritional science at the Chinese University of Hong Kong. "But we certainly do not recommend that people start consuming chilies to an excess. A good diet is a matter of balance. And remember, chilies are no substitute for the prescription medications proven to be beneficial. They may be a nice supplement, however, for people who find the hot flavour pleasant."
Chen and his colleagues turned to hamsters for the study, animals that serve as stand-ins for humans in research that cannot be done in people. They gave the hamsters high-cholesterol diets, divided them into groups, and supplemented each group's food with either no capsaicinoids (the control group) or various amounts of capsaicinoids. The scientists then analysed the effects.
In addition to reducing total cholesterol levels in the blood, capsaicinoids reduced levels of the so-called "bad" cholesterol (which deposits into blood vessels), but did not affect levels of so-called "good" cholesterol. The team found indications that capsaicinoids may reduce the size of deposits that already have formed in blood vessels, narrowing arteries in ways that can lead to heart attacks or strokes.
Capsaicinoids also blocked the activity of a gene that produces cyclooxygenase-2, a substance that makes the muscles around blood vessels constrict. By blocking it, muscles can relax and widen, allowing more blood to flow.
(EurekAlert, March 2012)