Podcast: Play in new window
If you like to use natural oils on your skin you’ll want to listen to this week’s show about the benefits of sesame oil. Plus, I try to stump Randy (and the audience) with a quiz about holiday foods in cosmetics.
Question of the week: Is sesame oil the best thing for your skin?
Amira asks…I read on The Food Babe website that sesame oil protects skin from bacteria, chlorine, UV rays, and cancer. And when it’s in your blood it prevents migraines, diabetes, and hepatitis. I’d love to hear your thoughts.
We hear claims like this about ingredients like this ALL the time. So we’re going to take this opportunity to give you the scientific scoop on sesame oil but we’ll also give you our step by step approach for assessing similar claims that you might encounter in the future. Sort of our blueprint for thinking skeptically about beauty science.
What the author actually say about sesame oil?
First step is make sure you understand what the author is actually claiming. It’s easy to mis read something or hear about it from a second hand source. So we went to the Food Babe website to see exactly what she said about sesame seed oil.
When you’re evaluating information from any source watch out for statements that appear to be generalizations or wild exaggerations. For example, the Food Babe says:
- “Don’t assume if you use a certain brand, your product is safe. Many companies have products across the spectrum from really safe and natural to horribly deadly.”
- “Your skin is your largest organ! What you put on your skin, is absorbed into your blood.”
If you want to learn more about skin penetration, check out our show #27, Can skin lotion make you fat.
In addition to wild assertions like these you should look for the specific claims the author makes. They say the devil is in the details and this is especially true when you’re looking into beauty science claims. Here are the claims verbatim:
“is considered one of the best because it contains several vitamins and minerals.”
“is naturally antibacterial.”
“is a natural sunscreen.”
“protects your skin from chlorine in a pool, radiation, and air pollution!”
“has been known to fight skin cancer.”
”when it is absorbed in your blood stream it can prevent migraines, diabetes and hepatitis.”
The second step is to look at the evidence provided for these statements.
Does the author provide sources of her information?
If I tell you that Stearamidopropyl dimethyl amine is an excellent hair conditioner, I don’t need to site any references because over the last 20 years I have personally formulated hair care products using this ingredient and have conducted hundreds of laboratory, salon, and consumer tests that generate data that indicates that formulas with this ingredient perform well on key hair conditioning attributes. But if I tell you a specific fact that involves research that I didn’t conduct, then you shouldn’t take my word for it and you should challenge me to document my sources.
So, does the Food Babe have the required expertise to back up her claims about sesame oil? Here’s her background:
She says that she was inspired to investigate “what is really in our food, how is it grown and what chemicals are used in its production. I had to teach myself everything…”
So, her experience involves about three years of self-directed study on healthy food choices. No indication of any kind of professional training or certification. Therefore, I think it’s reasonable to expect documentation on the kinds of skin care claims she’s making.
Does she site any external references that tell us where she gets her information about sesame oil? No, not all all. The ONLY reference she gives is to cite the EWG Skin Deep data base as proof that cosmetics contain dangerous ingredients but as informed listeners of our show already know, the EWG is known for driving a political agenda and doesn’t always present science accurately.
Since the Food Babe doesn’t have the background that makes her an expert and since she doesn’t provide references to support ANY of the claims she makes about sesame oil, we did some digging to see what kind of documentation we could find to support or refute these claims. Now we’ll break these down one by one starting with the claim that sesame oil contains several vitamins and minerals.
Sesame oil contains vitamins and minerals
To evaluate the first claim, about vitamins and minerals, we looked into the composition of sesame oil. (There’s a great paper titled simply “Sesame Oil” which appears in the 6th edition of Bailey’s Industrial Oil and Fat Products. Sesame Oil – ResearchGate.)
From that detailed paper we learned the following:
Sesame oil comes from sesame seeds – no surprise there. But the composition of the oil depends on what kind of sesame seeds. There are black seeds, yellow seeds, and brown seeds. But in general, sesame oil consists of about 80% oleic and linoleic acids. A lot of other vegetable oils are also rich in these two unsaturated fatty acids but sesame oil is unique because it contains approximately equal proportions of the two.
Compared to other vegetable oils sesame oil is relatively high in compounds such as sterols, triterpenes, tocopherols, and sesame lignans. Lignans which are complex molecules made of polyphenols. At least one of these lignans, called sesamol, is a powerful antioxidant. However, even though sesamol is found in sesame seeds only trace amounts are found in sesame oil. The concentration of sesamol also depends on how the seeds have roasted whether or not they were bleached, processed, deodorized, etc.
And finally, sesame seeds also contain a fair amount of protein and amino acids (about 25% total).
What does all this man? Since Vitamin E is a tocopherol it means the Food Babe is correct when she says that sesame oil contains a vitamin. However, as far as we can tell, it does NOT contain “several vitamins and minerals.” (And by the way, not all vitamins help your skin when applied topically anyway!)
Sesame oil is anti-bacterial
Let’s look at the second claim – that sesame oil is a natural antibacterial agent. A quick search in Pubmed revealed a paper “Antibacterial activities of the methanol extracts of seven Cameroonian dietary plants.” http://www.ncbi.nlm.nih.gov/pubmed/23961425 It says…”The results showed that Sesame seeds extract was active against 77.77% of the tested microorganisms.”
Note, however, that they tested an alcohol extract of sesame seeds, not actually sesame oil, and as we’ve seen the compounds in the seeds are not always present in the oil. So it’s probably more accurate to say that sesame oil has the potential to be antibacterial but I couldn’t find any other information confirming the efficacy of the oil itself.
So IF you’re applying pure sesame seed oil to your skin and IF that oil was processed in such a way as to maintain the properties of the seed extract, then yes, you might experience some anti-bacterial effect. Even if this is true I’m not sure what good that does you. If you’re just worried about casual protection from bacteria, your skin already does a good job of that with its acid mantle. And if you’re worried about disease transmission, you’re better off with a proven method of getting rid of bacteria like washing with soap and water.
Sesame oil is a natural sunscreen
This one is easy: I found a paper in Pubmed titled “In vitro sun protection factor determination of herbal oils used in cosmetics.” http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3140123/#!po=58.9286. One of which the oils evaluated was sesame oil and they found that it has an SPF of about 2 (1.77 to be exact.) Interestingly, olive oil and coconut oil were considerably higher with an SPF above 7. Of course proper sunscreens have an SPF of 20, 30, 50 or more. SPF in the single digits is NOT enough to protect you from damaging UV radiation.
So, if the Food Babe had said something like “sesame oil is a natural sunscreen but the value is so low that it can’t replace your sunscreen” she would have been correct. But she just said “it’s a natural sunscreen” implies that it CAN replace so called synthetic products. And furthermore, in the context of her article which is about the “best” natural oil, sesame doesn’t even come close to having the best SPF. No matter how you look at it, this claim is not true for all practical purposes.
Sesame oil protects from …chlorine in a pool, radiation, and air pollution
When you’re talking about this kind of protective effect on skin, for the most part, you’re talking about protection from oxidation. The antioxidant effect of sesame seed extract is well established because the sesame lignans we mentioned before work synergistically with the tocopherols.
There are two key measures used to determine how well an antioxidant functions: how many radicals it scavenges and how much lipid it stops from oxidizing. One study http://journal.scconline.org//pdf/cc2014/cc065n02/p00069-p00080.pdf says that sesamol has been tested in vitro and to be more effective than vitamin E at scavenging free radicals better less effective than vitamin E at stopping lipid oxidation.
The caveat once again is that the oil doesn’t contain very much of these magic lignans. You’d be better off rubbing crushed sesame seeds on your skin.
And finally, I couldn’t find any studies that directly assessed sesame oil for protection against chlorine but my guess is a good barrier cream that would prevent the chlorine from contacting your skin is probably the best defense.
Sesame oil fights skin cancer
Given the biological activity of some of the components of sesame seeds, it’s not all that surprising that there have been some benefits found in the anti-cancer research.
For example, when tested In vitro, Sesame seed oil has inhibited of human colon Cancer cells: ANTI Cancer RESEARCH 11: 209-216, 1992.
Sesame seed oil has inhibited the growth of malignant melanoma (a skin Cancer): PROSTAGLANDIN LEUKATRINES and ESSENTIAL Fatty Acids 46: 145-150, 1992.
The lignans we’ve been talking about have been shown to impact the production of prostaglandins which are influential factors for breast cancer.
And, when applied topically sesame oil components have been to inhibit the growth of certain artificially induced tumors.
So, there does seem to be some scientific basis for sesame oil components having the ability to affect certain types of cancers. However, once again I’m not sure what you do with this information. given the small amounts of the active lignans that are present in the oil it seems a bit foolish to rely on sesame oil for protection against skin cancer. If this is a real concern of yours I would suggest checking with your doctor.
I think making this kind of statement is particularly reckless: the implication is that using sesame oil will protect you from skin cancer. In reality it’s more nuanced…something like…some components of sesame seeds, which may or may not be present in the oil that you would buy for cosmetic purposes, have been shown to have an positive effect on some kinds of skin cancer when used at very high levels.”
Sesame oil treats migraines, diabetes, and hepatitis
Speaking of drug claims…the idea that sesame oil treats migraine, diabetes and hepatitis are CERTAINLY drug claims and we couldn’t find any evidence that topically applied sesame oil provides any of these benefits. However, I did find several studies on the nutritional benefits of sesame oil that did talk about about its impact on liver function and its ability to modify the way the body produces insulin. These are animal studies that evaluated the effects of ingesting high levels of these sesame lignans, so you certainly can’t assume that topically applied sesame oil will have the same effect.
Does sesame seed oil moisturize skin?
I’d like to talk about one more function of sesame oil that Food Babe didn’t bring up – moisturization. Oils moisturizer by preventing water from evaporating out of your skin. We call this occlusivity.Since sesame seed is an oil it makes sense that it could be a good moisturizer. But is it?
If found a paper (A new in vitro method for transepidermal waterloss:A possible method for moisturizer evaluation J. SCC 39, 1988) http://journal.scconline.org//pdf/cc1988/cc039n02/p00107-p00119.pdf
which measured the effect of sesame oil on water loss through the skin. Here’s what it found:
Negative control: With no oil applied to skin – lose about 400 micrograms of water per cm2 per hour initially, then levels off to about 300.
Positive control: Mineral oil, which we know to be an excellent occlusive agent, lowers water loss to about 80 to 100 micrograms of water per cm2 per hour.
With sesame oil on skin, skin loses about 250 to 300 micrograms of water per cm2 per hour.
So sesame oil isn’t much better than using nothing!
So it helps a little bit but no where near as effective as mineral oil.
And finally, by the way, at least one study says sesame oil is moderately to severely comedogenic: https://www.dowcorning.com/content/publishedlit/25-528-93.pdf
The Beauty Brains bottom line
So the bottom line for Amira is that sesame oil does appear to be a good source of antioxidants and it may help protect against some forms of skin cancer.
However, these benefits are highly dependent on the presence of sesame seed components that are not contained in the oil at a very high concentration which makes it unlikely that you’ll actually experience these benefits.
Sesame oil is a lightweight emollient and it feels good on your skin but there’s little to indicate that it’s “the best” natural oil to use.
Perhaps more importantly, we’ve explained the process you can use to evaluate similar claims that you find in the future. Of course, if you don’t have time to do the research yourself you can always ask the Beauty Brains so send us your questions!
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