…people who like spicy foods tend to consume less salt and have lower blood pressure than those who dislike spicy foods. Obviously, eating spicy foods usually triggers the acute desire to drink more water and people hardly look for salt shakers to appease the hot sensation.


Introduction

Plants do not have the benefit of running away from their predators or the privilege to move towards benefical seed dispersals. Like most plants, chili peppers attract birds with their bright fruits and uniquely ward off mammals through a pungent irritant compound called capsaicin. Chili seeds retain the integrity to germinate after consumption and defecation by birds. However, these seeds cannot survive the chewing and grinding when consumed by mammals. Therefore, the capsaicin compound is seed protective and acts to “inflict” hot and burning sensations on contact with the mouth, eyes and skin of all mammals. Interestingly, the birds lack the receptor for capsaicin and are not affected by the pungent sensation felt by rodents and man.

To buttress the protective effects of capsaicin on peppers’ survival, a 2001 study performed a feeding trial involving rodents and birds on hot and non-spicy peppers. While the birds consumed the spicy fruits like “candy”, the mice avoided the hot peppers altogether. This study was in agreement with my experience in rural Nigeria, where peppers are usually dried in the sun for long term storage. Parents and neighbours often asked kids to keep an eye on the drying peppers, and the concern was never about the stubborn village goats and sheep but to watch out for the persistent roaming hens and cocks who would gleefully feed on the pepper fruits.

In addition, it has been observed that hot and high humid environments increase the pungent intensity of chili peppers in the wild. This ensures that fungi and moulds are unable to thrive on the fallen fruits, as the chili “heat” protects the seeds from infections prior to germination.

Peppers and Scoville Scale

The intensity of chili “heat” is subjectively measured in Scoville heat units. This measurement simply refers to the number of times a pepper extract must be mixed with water for it to lose the heat. At the low end, bell peppers measure 0 to 25 on the Scoville scale and Jalapenos have 1,000 to 10,000 Scoville heat units. At the very intense levels, Habanero and Carolina Reaper have up to 350,000 and 3.2 million Scoville heat units respectively.

Health Benefits of Chili Peppers

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Although chili peppers originated from South America, there are lots of African proverbs that recognise the health benefits of peppers. In my Yoruba language, there is a proverb that loosely translates to the fact that a pepperless soul is an unviable living spirit.

Humans can feel the spiciness of chili peppers because they have what is called a transient receptor potential vanilloid 1 (TRPV1). This receptor is abundantly present in pain carrying nerves, the linings of blood vessels called endothelium and in other organs like the kidneys, brain, fatty tissue and heart. A 2016 review reported that more than 80 percent of capsaicin is passively absorbed in the stomach and upper part of the small intestine. Therefore this active compound in peppers can easily be transported to various organs and tissues where it exerts varying beneficial health effects, which include blood pressure and weight control.

Hypertension: Briefly, when dietary capsaicin from chili peppers docks on TRPV1 found in blood vessel lining, it mimics the shear stress associated with exercise by activating and increase production of an enzyme called eNOS. This enzyme produces anti-hypertensive gas that relaxes the blood vessels and prevents the narrowing of the vascular tree over a period of time. In the kidney, capsaicin interacts with TRPV1 to decrease the so called (epithelial) sodium channels and interfere with the optimal functioning of the existing channels. This reduces sodium reabsorption and increases urinary sodium excretion with clinical low blood pressure.

In addition, a 2017 study in a Chinese population showed that capsaicin tricks the brain to raise salt sensitivity and reduces the individual’s salt preference. In other words, people who like spicy foods tend to consume less salt and have lower blood pressure than those who dislike spicy foods. Obviously, eating spicy foods usually triggers the acute desire to drink more water and people hardly look for salt shakers to appease the hot sensation. As a matter of fact, the study reported a decrease of eight points in the upper blood pressure and a five-point lowering in the bottom of blood pressure numbers for those who enjoyed spicy foods.

Weight Control: Activation of TRPV1 by capsaicin increases the production of certain protein transporters called uncoupling protein 2 (UCP2) in the blood vessel lining, heart and liver. Chronic levels of blood glucose and excessive food consumption lead to a “sluggish” metabolic rate as ATP generation is much slower than the available oxidation molecules. This results in pent-up energy and excessive formation of superoxide, otherwise called oxidative stress. Capsaicin chili triggers the increased presence of UCP2, which helps to dissipate this metabolic energy to heat and thus reduces excessive superoxide radicals that may cause the stiffening and narrowing of blood vessels.

In compliance with the law of thermodynamics, energy not used will be stored. This action of UPC2 assists in energy expenditure and weight control as it burns off the energy that otherwise would have been stored to heat – a process called thermogenesis. Specifically, the chronic presence of dietary capsaicin prevents fat deposition in the liver and generally reduces pot belly. Several studies have reported that dietary capsaicin in peppers also increase the sensation of fullness and therefore increase satiety. This makes sense in a lot of ways because as enjoyable as spicy foods could be, it is quite unlikely for one to overeat in the presence of capsaicin “heat”. This is particularly important as eating less is the primary short-term weight control. Capsaicin acts on the fatty tissue to facilitate the increased production of a hormone called adiponectin, which also contributes to increased fat burning and opposes weight gain.

Conclusion

Generally people have different responses to the same food. Oftentimes, a plate of food may elicit strong and opposite reactions, as someone’s yammy food is another’s yuck stuff! Understandably, some individuals cannot tolerate spicy foods, not necessarily because of the heat sensation but due to pepper allergy and genuine stomach troubles. However, for those who can stand the heat, raising the “spicy kick” is a good addition to very many healthy behavioural choices.

Mukaila Kareem, a doctor of physiotherapy, writes from the USA.