Dear Mark: Fruit Wax, Placentophagy, and Second Hand Smoke

Fruit WaxFor today’s edition of Dear Mark, I’ll be covering several topics. First, I cover fruit wax, that lovely layer of ultra-thin sheen applied to many fruits and vegetables in the grocery store. Is it harmful or innocuous? Find out below. Next up is one that makes most people extremely squeamish: placentophagy, or the consumption of the placenta by the mother following birth. Does it do anything? Should people do it? What’s the deal with it? Finally, I field a question from a guy who hangs out in a bar for a few hours a week with his friends. All good, right? Unfortunately, this particular bar allows smoking, so he’s wondering whether or not he’s doing any real damage to himself from exposure to second hand smoke.

Let’s go:

How about an article on the effects of wax that is put on apples and other fruits and vegetables at supermarkets?



The idea of wax on your food sounds a little unsettling, but I don’t think it necessarily poses a health risk. Let’s look at the various sources used:

Carnauba wax, drawn from the carnauba tree, seems quite safe. Toxicology studies on rats and dogs found it to be non-toxic, even to developing fetuses.

According to European officials (who, compared to the FDA, tend to be less lax when it comes to approving food additives), candelilla wax is also non-toxic.

Shellac wax comes from a kind of beetle, and officials are still trying to determine its safety. It’s probably not a big issue, though.

Though it’s more expensive, food producers sometimes use beeswax. Beeswax is safe (as anyone who’s ever chewed on honeycomb could tell you).

Besides, they’re just replacing the natural wax that gets removed during processing. From what I can tell, all fruits produce a thin layer of wax as a protective barrier between them and their environment, mostly to repel water and prevent moisture from escaping the fruit. In fact, the major component of natural apple wax is ursolic acid, a powerful water repellant (PDF). If you’ve ever plucked an apple from a tree, rubbed it, and gotten white powder on your hands, that’s the natural wax rubbing off. Our attempts to replicate, replace, or modify natural components of foods often get us into trouble, but I don’t think fruit wax is one of these instances. Just peel the fruit, if you’re worried, and be on your way.

One caveat: some conventionally-grown fruits may have a petroleum-based wax. I would avoid those if I were you, so be sure to ask the head of the produce department what kind of wax was used on the fruit you’re considering. They should have that information.

One more caveat: conventional fruit that travels a great distance – like, say, from Chile to California – may be treated with a fungicide in addition to a wax to prevent contamination. If that’s the case, you’ll probably want to peel your fruit, or give it a light wash with a vinegar-hydrogen peroxide-water solution. Or, just, ya know, buy local when possible. Produce at farmers’ markets generally doesn’t have wax on it.

Love the few topics recently on babies (co-sleeping etc).

I am wondering what your thoughts are on Placenta Encapsulation? Do you think our primal ancestors ate their placentas? How beneficial could this be to new mothers?


Most mammals eat their placenta after giving birth. Primates (both high and low), carnivores, rodents. Not just the carnivores, either. Herbivorous cows will readily eat the placenta, perhaps the only time in a cow’s life that she ever feels the need to eat animal flesh. Only marine mammals and certain semi-aquatic mammals do not for obvious logistical reasons. Marsupials don’t do it (the placenta is resorbed upon birth), but they do avail themselves of the birth fluids.

Opponents of placentophagy dismiss the relevance of other animals consuming their placentas with claims that they only do it to “hide the smell” from predators. Even if that were the primary motivation (and I doubt it is, seeing as how firstly, top predators with no hope of being prey themselves also practice it and secondly, all the other birth fluids that aren’t eaten are just as likely to attract attention), just because a trait appears to be selected for its benefit to immediate, direct survival doesn’t preclude it from offering other benefits. Monkeys aren’t drawn to sweet fruits because of a conscious desire for vitamin C and flavonoids. They just like the sugar. Evolution can be tricky and devious, and I strongly suspect there are other, deeper reasons for the ubiquity of placentophagy.

There’s actually not a ton of research. In 1980, a review of the literature (PDF) contains some interesting stuff:

  • Otherwise herbivorous mammals aren’t driven to placentophagy because of the sudden proximity of free (organ) meat; you can present other types of meat to mammals immediate after delivery and they’ll still prefer the placenta.
  • Very little evidence of placentophagy exists in the anthropological literature. In fact, many cultures explicitly forbade placentophagy. One exception is China, where placentophagy has been used in traditional medicine for over 2,000 years.
  • Among virgin rats given the opportunity to eat a placenta, placentophagy is extremely rare. They’re just not that into it. After their first delivery of a pup, however, they become “enthusiastic placenta-eaters.”
  • A 1954 human study found that 86% of new mothers given placenta experienced a boost in milk production and flow, while just 33% of the mothers given an identical preparation of beef experienced improved lactation.
  • Placenta-deprived rats showed no difference in postpartum estrus when compared to rats who were allowed to eat the placenta.
  • In rare cases, mothers experience an immunological rejection of the fetus, which can have obviously negative effects on its viability. Placenta eating may improve the mother’s immune response to the presence of a fetus in later pregnancies by preventing the formation of fetal tissue antibodies. Totally hypothetical, but interesting.

So no, concrete benefits have yet to be established. That doesn’t mean it’s totally baseless as a practice, though. Placenta is apparently rich in iron, and iron deficiency is a possible cause of postpartum depression – maybe it’s a reliable way for mammals to obtain iron in an iron-deprived state? It may also affect pain suppression following birth by way of endogenous opioid receptors.

There are reports of negative reactions to encapsulated placenta, but that may be due to the presence of other additives. This woman, for example, who regrets eating her placenta and had numerous negative reactions, had it encapsulated with unknown “cleansing herbs.” As we know from last week’s post, herbs can have powerful effects on our physiologies – and they’re not always beneficial. It might be worth it to keep the placenta pure and free of additives, no matter how innocuous and helpful they sound. Actual placenta seems fairly safe, even if it isn’t doing anything beneficial.

I’m intrigued by the idea of placentophagy, but I’m not convinced it’s vital. Humans don’t appear to have a biological imperative to practice it. At least, not like other mammals do. That said, many women swear by it as a way to stave of depression and provide energy. It’s harmless, so I can’t see a reason not to do it if you’re interested.

Dear Mark,

I am not a smoker, but most of my friends are and we typically hang out at a bar that is still not smoke free about once a week for a few hours. I’ve tried to do a little research on the amounts and time exposure to second hand smoke and amount of damage, but can’t find much quantitative stats. Was hoping you might have a little more insight into how much and the potential harmful effects would be?

Thanks for all the work you and your team do with the website. It is very beneficial.


Well, one study found that service staff working in places that were not smoke free gradually accumulated levels of NNK, a tobacco carcinogen, at a rate of 6% every hour. That’s worrisome, seeing as how NNK (or Nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone) is what researchers typically use to reliably induce lung cancer in lab rats, and it promotes cancer in human in vitro studies (you can’t exactly run an RCT where you give actual humans a known carcinogen). Another study found that just 20 minutes of second hand smoke exposure was enough to negatively affect breathing function in humans. You could probably argue about the relevancy of their setup to your situation (were they emulating smoking in a car or a bar?), but 20 minutes is worrisome.

Second hand smoke is demonstrably bad for you, regardless of what industry-funded studies say, but hanging out with friends is demonstrably good for you. What to do?

Pick a new spot. I’m sure there are smoke-free bars around. If there aren’t, suggest a new genre of venue entirely to your friends.

Support your detoxification ability. One study found that pycnogenol, a naturally-occurring bioflavonoid, enhanced the body’s metabolism of NNK and reduced its carcinogenic effects on the lungs (though not on the liver). Pop a few before going out to the bars, if you insist on it. Pycnogenol has also been used in cigarette filters to scavenge free radicals, reduce mutagenicity, and detoxify smoke as it flows through the cigarette itself (better than nothing, I suppose). A beta-carotene/vitamin E/vitamin C cocktail may also mitigate the damage done by NNK and second hand smoke.

In short, avoid the second hand smoke if you can, but if you can’t (and even if you can), at least maintain a consistent intake of polyphenol and antioxidant-rich vegetation. In your case, I think the benefit of hanging out with friends probably outweighs the risk of a few hours of second hand smoke exposure. It’s not that second hand smoke is safe; it clearly is not. It’s that socializing is essential.

That’s it for today’s post, guys. Leave a comment and thanks for reading!

About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

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