Introduction

I first came across culinary medicine as a child. We were on a family holiday and befriended a family of Indian descent who had been displaced from their farmland in Uganda by Idi Amin. At selected times during the day, the family would take specific spices and herbs to balance their doshas.

It fascinated me to think that health was something that you crafted by everyday conscious choices and not something that the medical profession monopolized.

Nowadays, culinary medicine is gaining popularity outside of Indian Ayurvedic and Traditional Chinese Medicine. Spices are a cornerstone of culinary medicine. They are generally low or no calorie condiments that sometimes also offer health benefits.

They also taste great which is a major plus with some of the more bland health foods (yes, tofu, I am talking about you).

One of the most commonly used culinary spices are chilli peppers. Up to 25% of the worlds population use chilli peppers on a daily basis. Cayenne peppers are one of the more popular of the chilli peppers.

In this article, we will review the data behind the use of cayenne pepper as a form of culinary medicine. Though as we will see, it is hard to separate out the effects of ‘cayenne’ peppers versus other forms of chilli peppers because of similarities in their make-up.

What Is Cayenne Pepper?

Chilli peppers have been used since 7000 BC. Cayenne pepper is a type of Capsicum annuum pepper of the Solanceae family. Cayenne is the name of a town in French Guiana and it is unclear if the town gave the chilli its name or if the chilli have the town its name.

Capsaicin ( trans-8-methyl-N-vanillyl-6-noneamide) is the pungent principle of the Capsicum red pepper meaning the main source of taste or smell of the pepper. This is a fat soluble substance which is classified as a vanilloid. Interestingly capsaicin is probably produced as a defence mechanism by chillis to protect them against herbivores and fungi. 

In addition to capsaicin, cayenne also contains dihydrocapsaicin norhidydricapsaicin homocapsaicin and homodihydrocapsaicin (1). These are collectively called capsaicinoids.

Capsaicin was first identified and extracted from chilli peppers in 1816 and it got its name in 1846. Topical chilli was first formally recommended for medicinal use in the western world in 1850 (2).

This report came from my home town of Dublin. While the Irish may have formally codified the medicinal properties of chilli, ancient civilizations had already been using chilli peppers therapeutically for ages.

Sadly,I think we can all agree that while the Irish may have talked about chilli peppers,  it was all talk and chilli never made its way into Irish cuisine (which is one of the great tragedies of Irish history if you ask me).

Like many spices, cayenne pepper contains no calories, no fats and no carbohydrates (3). It does contain some vitamin A- approximately 50,000IU per 100gms.

Cayenne peppers are small (10-25 cm), red, curved peppers which have a Scoville score of 30,000 to 50,000 (4).The Scoville score measures how hot a chilli pepper is. To put this into context, the habenero chilli has a score of 350,000.

There are over 8000 cayenne related products on sale on Amazon. A 500mg cayenne pepper pill costs approximately $0.20.

Is There Any Research?

There are 4800 papers and 100 clinical trials on cayenne pepper. There are almost 15000 papers and 860 clinical trials on capsaicin.
For the purposes of this review, we will include data on cayenne and capsaicin.

Does Cayenne Pepper Prevent Blood Clots?

There are no human clinical studies showing that cayenne pepper can prevent blood clots.

There are two positive non-human studies.

One study showed that capsicum can prevent platelet aggregation (platelets sticking together which can cause clots) (5).

This study was done on blood samples.

A second study showed that capsicum inhibited platelet aggregation in 6 beagle dogs (6)

Bottom Line

There is no human clinical evidence to support a role for cayenne pepper in the prevention of clots.

Does Cayenne Pepper Relieve Migraine Pain?

Italian investigators found that a 0.1% capsaicin gel was statistically significantly better than vaseline at relieving arterial tenderness between and during migraine attacks (7).  The study was done in 23 migraineurs which was a small number of patients.

The following is definitely not something to be tried at home. Italian investigators randomized 8 migraineurs to either placebo or 100 µl of an emulsion containing capsaicin 300 µg dissolved in 80% saline solution, 10% paraffin oil, and 10% polyethylene glycol sorbitan monooleate (Tween® 80, Sigma-Aldrich), applied in both nostrils once a day for 7 days (8).

Even though the study subjects reported a burning nasal sensation, none of the study subjects dropped out of the study. The capsaicin group reported a 50-80% improvement in their symptoms while the placebo arm noted a 20% improvement.

This difference was statistically significantly different in favor of the capsaicin arm of the study. Again the numbers in the study are really small.

Bottom Line

There is very limited data which is based on 29 study subjects which does suggest that capsicum may help migraine.

Does Cayenne Pepper Help Treats Psoriasis?

A double-blind study randomized 98 patients with psoriasis to capsaicin 0.025% cream and 99 patients to a placebo vehicle four times a day for 6 weeks in this double-blind study (9). Patients in both arms of the study reported a burning sensation.

Thi again shows the power of the mind. Why else would the placebo vehicle burn? There was a statistically significant difference in itch and psoriasis severity score in favor of the capsaicin arm of the study.

A study done over 30 years ago looked at the effect of topical capsicum in 44 patients with psoriasis (10). All patients had psoriasis on both sides of their body and just applied the capsicum to just one side of their body.

They then compared the appearance of the skin in the treated side of their body to the untreated side of the body.

The final study conclusion was that capsicum helped with psoriasis. The fact that this study is over 30 years old and has not been followed up by larger and more in-depth studies suggests to me that the academic world was underwhelmed by the results of this study.

Just in case you are as nerdy as me, the first psoriasis study that I mentioned was done in 1993 and has had no major follow up either (9).

Bottom Line

There are very limited short-term data suggesting that capsicum may help with psoriasis.

Does Cayenne Pepper Helps Fight Cold and Flu?

There are no pre-clinical or clinical studies evaluating cayenne pepper to flus and colds.

Bottom Line

There are no studies linking cayenne pepper to treating flus and colds.

Does Cayenne Pepper Prevent Allergies?

There are no studies showing that cayenne pepper can prevent allergies.

In fact, cayenne pepper by its very nature is an irritant which goes against it preventing allergies. On the other hand, there is some theoretical basis to suggest that capsicum receptors may play a role in inflammation.

This is very theoretical and not even something that we can provide a credible reference for at this stage. Anaphylaxis has been reported to capsicum annum in a patient with latex-fruit allergy (11).

Bottom Line

There are no studies showing that cayenne pepper can prevent allergies.

Does Cayenne Pepper Support Weight Loss?

A very popular drink among my friends is water with added lemon, cayenne pepper and ginger. It tastes great and is supposed to help with weight loss. True or false?

A review paper this year from Iran looked at capsicum for metabolic syndrome (high BP, high glucose, high cholesterol and high BMI)
(12). The review included preclinical and clinical studies. Overall the paper concluded that red pepper was beneficial for hyperlipidemia, obesity and diabetes.

Specifically in relation to weight loss, the paper concluded that ‘Taken together, red chilli pepper containing capsaicin could play beneficial effects in weight management via increase energy expenditure, satiety, fat oxidation and thermogenesis which are the main mechanisms of anti-obesity effect of capsaicin’.

The problem here is that the article mostly summarised studies as opposed to doing a full meta-analysis

A 2017 Chinese review focused on dietary capsaicin as an anti-obesity tool (13).They first looked at data from 9 preclinical studies (fat cells mice and rats).

They also looked at 5 clinical trials. The clinical trial data came from 311 people with very diverse backgrounds ( college students, healthy adults, overweight adults and post menopausal women).

The longest study was still quite a short study and only lasted 12 weeks. Overall they concluded that capsaicin could promote weight loss in obese individuals.

I really respect the quality of data that comes from meta-analysis. On the other hand, I like to look at the actual studies (especially clinical trial data) to get a better feel for the science. Here are some details on relevant clinical trials.

University of Maryland researchers randomized 40 men and 40 women to either 6 mg/day of capsaicinoids or placebo for 12 weeks (14). There was no significant difference in weight or overall adiposity between the groups. A statistically signifiant reduction in abdominal adiposity was noted in the capsaicinoid arm of the study.

A 2009 study looked at the effect of capsaicin on energy expenditure and satiety at lunch in the postprandial state (15). A total of 30 subjects took part in this study in a cross-over design.

This meant that the 30 subjects had a lunch with capsaicin and then one week later had lunch without capsaicin (or the other way around for some of the study subjects). The results of the study showed that the capsaicin had no effect on satiety or energy expenditure.

Bottom Line

There are no large robustly designed clinical trials proving that cayenne can help with weight loss. A hodge-podge of related studies suggest that cayenne pepper may help with weight loss.

Does Cayenne Pepper Help Digestion?

There is really just one (vaguely) relevant study to consider here.

Firstly, a paper published in 2016 stated that the salivary gland has capsicum receptors (transient receptor potential vanilloid subtype 1) and can increase saliva production (16). As saliva aids the digestive process, could it be inferred that cayenne can help with digestion? Possibly. However, this is an extrapolation and is not based on an actual clinical trial.

Bottom Line

There is no convincing clinical data to show that cayenne pepper can aid digestion.

Does Cayenne Pepper Help Relieve Joint and Nerve Pain?

Chilli pepper has been used as an analgesic since antiquity.  We used to think that capsaicin worked by depleting the reserves of substance P in nerve cells which is the neurotransmitter that usually sends pain signals to the brain. That theory has now been debunked.

The current theory behind the analgesic effects of chilli is as follows. Topical capsicum from chilli peppers binds to receptors including the transient receptor potential vanilloid subtype 1 (TRPV1 receptor) which causes a burning sensation and blocks other sensations for sometime. This is known as the counter-irritation theory.

Put another way, the capsicum acts as a placeholder and prevents other causes of pain from registering. Scientifically, this is referred to as ‘defunctionalization’ of nociceptor fibres.

As such, capsaicin can induce opposite effects depending on the dose and duration of use ie burning skin with short term use or pain relief with longer term use (1).

In 2009, the FDA approved a capsicum patch for pain relief in patients with post-herpetic neuralgia which is a specific type of nerve pain that can be a consequence of herpes infections (17).

A 2017 study reviewed data from 6 post-herpetic neuralgia  trials involving 1347 study participants and found that all studies showed favorable results and the literature review found that topical capsicum was effective as a sole agent in the management of pain (18). However, there were two big problems with the papers.

Firstly, the significance of these results could not be calculated due to inter-study methodological differences. Secondly, two of the studies included in the review were funded/sponsored which raises the issue of conflict of interest. The reviewers concluded that they could not conclude anything. Oops.

An ongoing study is comparing the efficacy of on-steroidal anti-inflammatories to capsicum in people with arthritis (19). The study protocol was published in 2016 by the osteoarthritis trial bank consortium but the analysis is still ongoing.

Bottom Line

Capsicum is recognised as beneficial for certain types of nerve pain eg post-herpetic neuralgia.

Is Cayenne Pepper Safe?

Cayenne pepper is generally recognised as safe by the FDA (20). This is referring to small amounts of cayenne being sprinkled on food. Like anything else, common sense has to prevail.

Capsaicin is also the main ingredient in pepper spray (21). Have you even chopped chillis and then rubbed your eye?

The scientific literature agrees with this. A 2007 review paper  reported on studies in mice rats and rabbits and found that capsaicin is safe but can be irritant to the eyes and skin (22). 

The paper also commented on the fact that the irritant properties of capsaicin means that it  can also increase the absorption of agents though human skin means that care should be exercised if using capsaicin in cosmetics or as part of any topical treatments.

Capsicum can result in increases in blood pressure and special care is recommended when suggesting this as an analgesic in people with hypertension ( 23 ).

A 2014 review noted that capsicum has been reported as a possible causative factor in gastric cancer (24). The study found that low to moderate intake of capsaicin offered protection against stomach cancer while high intake was possibly associated with a higher than average risk of stomach cancer.

In 2012 Turkish emergency room physicians reported an unusual case of a heart attack in a 25 year old man (25). This man had no risk factors for heart disease. He had been taking cayenne pepper supplements for weight loss. Usually heart attacks happen in people with diseased heart vessels.

 This young man had perfectly normal heart vessels on coronary angiography. It seems that the cayenne pepper caused his blood vessels to go into spasm.

Another theoretical concern with capsicum is that it may permanently block pain perception and actually lead to neuropathy.

Conclusion

It is difficult to specifically comment on cayenne pepper versus any other kind of pepper. Most of the research relates to the ‘pungent principle’ which are the capsaicinoids.

Overall, capsaicinoids may help relieve pain and migraines but are not without side effects. 

That being said, I suspect that capsaicinoids are safer when used in culinary medicine doses where the sheer burning of the chilli usually limits how much people consume on any given sitting.

Nature has an in-built safety check when it comes to chilli peppers. The problems may well just be an issue when we apply our ‘supersize me’ approach to life and try to ingest industrial grade amounts of capsicum or spray capsicum into our opponents eyes.