Capsaicin’s Hot Benefits

Capsaicin, the compound in hot peppers that makes them spicy, is a chemical irritant and a neurotoxin. However, humans being humans, we decided to eat them for fun.

In contrast to many other ways in which humans recreationally enjoy things that are objectively poisonous, consuming capsaicin (in moderation) is considered to have health benefits, such as aiding weight loss (by boosting metabolism) and reducing inflammation.

Let’s see what the science says…

First: is it safe?

Capsaicin is classified as “Generally Recognized As Safe”. That said, the same mechanism that causes them to boost metabolism, does increase blood pressure:

Mechanisms underlying the hypertensive response induced by capsaicin

If you are in good cardiovascular health, this increase should be slight and not pose any threat, unless for example you enter a chili-eating contest when not acclimated to such:

Capsaicin and arterial hypertensive crisis

As ever, if unsure, do check with your doctor first, especially if you are taking any blood pressure medications, or otherwise have known blood pressure issues.

Does it really boost metabolism?

It certainly does; it works by increasing oxygen consumption and raising body temperature, both of which mean more calories will be burned for the same amount of work:

Dietary capsaicin and its anti-obesity potency: from mechanism to clinical implications

This means, of course, that chili peppers enjoy the status of being functionally a “negative calorie” food, and a top-tier one at that:

Chili pepper as a body weight-loss food

Here’s a good quality study that showed a statistically significant* fat loss improvement over placebo:

Capsaicinoids supplementation decreases percent body fat and fat mass: adjustment using covariates in a post hoc analysis

*To put it in numbers, the benefit was:

• 5.91 percentage points lower body fat percentage than placebo
• 6.68 percentage points greater change in body fat mass than placebo

See also: Difference between percentages and percentage points

For those who prefer big reviews than single studies, we’ve got you covered:

The Effects of Capsaicin and Capsiate on Energy Balance: Critical Review and Meta-analyses of Studies in Humans

Does it really reduce inflammation?

Counterintuitive as it may seem, yes. By means of reducing oxidative stress. Given that things that reduce oxidative stress tend to reduce inflammation, and in turn tend to reduce assorted disease risks (from diabetes to cancer to Alzheimer’s), this probably has more knock-on benefits too, but we don’t have room to explore all of those today.

Fresh peppers are best for this, but dried peppers (such as when purchased as a ground spice in the supermarket, or when purchased as a capsule-based supplement) still have a very respectable anti-inflammatory effect:

• Capsaicinoids, Polyphenols and Antioxidant Activities of Capsicum annuum: Comparative Study of the Effect of Ripening Stage and Cooking Methods
• A Review on the Effect of Drying on Antioxidant Potential of Fruits and Vegetables

How much should we take?

It’s recommended to start at a low dose and gradually increase it, but 2–6mg of capsaicin per day is the standard range used in studies.

If you’re getting this from peppers, then for example cayenne pepper (a good source of capsaicin) contains around 2.5mg of capsaicin per 1 gram of cayenne.

In the case of capsules, if for example you don’t like eating hot pepper, this will usually mean taking 2–6 capsules per day, depending on dosage.

Make sure to take it with plenty of water!

Where can we get it?

Fresh peppers or ground spice from your local grocery store is fine. Your local health food store probably sells the supplements, too.

If you’d like to buy it online, here is an example product on Amazon.

Note: options on Amazon were more limited than usual, so this product is not vegan, and probably not halal or kosher, as the capsule contains an unspecified gelatin.

As “trending” health products go, castor oil is enjoying a lot of popularity presently, lauded as a life-changing miracle-worker, and social media is abuzz with advice to put it everywhere from your eyes to your vagina.

But:

• what things does science actually say it’s good for,
• what things lack evidence, and
• what things go into the category of “wow definitely do not do that”?

We don’t have the space to go into all of its proposed uses (there are simply far too many), but we’ll examine some common ones:

To heal/improve the skin barrier

Like most oils, it’s functional as a moisturizer. In particular, its high (90%!) ricinoleic fatty acid content does indeed make it good at that, and furthermore, has properties that can help reduce skin inflammation and promote wound healing:

Bioactive polymeric formulations for wound healing ← there isn’t a conveniently quotable summary we can just grab here, but you can see the data and results, from which we can conclude:

• formulations with ricinoleic acid (such as with castor oil) performed very well for topical anti-inflammatory purposes
• they avoided the unwanted side effects associated with some other contenders
• they consistently beat other preparations in the category of wound-healing

To support hair growth and scalp health

There is no evidence that it helps. We’d love to provide a citation for this, but it’s simply not there. There’s also no evidence that it doesn’t help. For whatever reason, despite its popularity, peer-reviewed science has simply not been done for this, or if it has, it wasn’t anywhere publicly accessible.

It’s possible that if a person is suffering hair loss specifically as a result of prostaglandin D2 levels, that ricinoleic acid will inhibit the PGD2, reversing the hair loss, but even this is hypothetical so far, as the science is currently only at the step before that:

In silico prediction of prostaglandin D2 synthase inhibitors from herbal constituents for the treatment of hair loss

However, due to some interesting chemistry, the combination of castor oil and warm water can result in acute (and irreversible) hair felting, in other words, the strands of hair suddenly glue together to become one mass which then has to be cut off:

“Castor Oil” – The Culprit of Acute Hair Felting

👆 this is a case study, which is generally considered a low standard of evidence (compared to high-quality Randomized Controlled Trials as the highest standard of evidence), but let’s just say, this writer (hi, it’s me) isn’t risking her butt-length hair on the off-chance, and doesn’t advise you to, either. There are other hair-oils out there; argan oil is great, coconut oil is totally fine too.

As a laxative

This time, there’s a lot of evidence, and it’s even approved for this purpose by the FDA, but it can be a bit too good, insofar as taking too much can result in diarrhea and uncomfortable cramping (the cramps are a feature not a bug; the mechanism of action is stimulatory, i.e. it gets the intestines squeezing, but again, it can result in doing that too much for comfort):

Castor Oil: FDA-Approved Indications

To soothe dry eyes

While putting oil in your eyes may seem dubious, this is another one where it actually works:

❝Castor oil is deemed safe and tolerable, with strong anti-microbial, anti-inflammatory, anti-nociceptive, analgesic, antioxidant, wound healing and vasoconstrictive properties.

These can supplement deficient physiological tear film lipids, enabling enhanced lipid spreading characteristics and reducing aqueous tear evaporation.

Studies reveal that castor oil applied topically to the ocular surface has a prolonged residence time, facilitating increased tear film lipid layer thickness, stability, improved ocular surface staining and symptoms.❞

Source: Therapeutic potential of castor oil in managing blepharitis, meibomian gland dysfunction and dry eye

Against candidiasis (thrush)

We couldn’t find science for (or against) castor oil’s use against vaginal candidiasis, but here’s a study that investigated its use against oral candidiasis:

Rosemary, Castor Oils, and Propolis Extract: Activity Against Candida Albicans and Alterations on Properties of Dental Acrylic Resins

…in which castor oil was the only preparation that didn’t work against the yeast.

Summary

We left a lot unsaid today (so many proposed uses, it feels like a shame to skip them), but in few words: it’s good for skin (including wound healing) and eyes; but we’d give it a miss for hair, candidiasis, and digestive disorders.

Want to try some?

We don’t sell it, but here for your convenience is an example product on Amazon 😎

Take care!