Dear Mark: Candle Fumes Safety, Quest Bar Carbs, Minimalist Shoes for Track, and Walnut Oil

CandleFor today’s edition of Dear Mark, we’ve got a four-parter. First up, how safe are indoor candles? Do some emit toxic fumes? Are there certain types of candles we should prefer over others? The second question concerns the carb content of Quest Bars. Can we really disregard all the fiber and sugar alcohols when determining the amount of digestible carbohydrates contained in the bars?  Third, what should a high school track athlete look for in a minimalist running shoe, assuming Vibram Fivefingers are out of the question? I help her narrow down the most important attributes. And finally, I may caution against making high omega-6 nut oils like walnut oil a daily staple, but do those recommendations change if a person is using it to actively solve a health issue?

Let’s go:

Hi Mark –

Do you have any concerns with the heavy or daily use of candles in a home (e.g., in an effort to reduce blue light in evening)? Some sources say that candles put off toxins. What’s your take? What about scented candles? Are there any candles safer than others?


(P.S. Primal Blueprint Certified Expert #75!)

Most candles sold nowadays are made from paraffin wax, a byproduct of petrochemicals. Burning them can release benzene and toluene, two chemicals linked to certain cancers and asthma. If the wick is lead-based (as many wicks with a metal interior are), it also releases aerosolized lead into the air. If the artificial fragrances in your scented candle are anything like those in cosmetics, their manufacturers don’t have to disclose the chemicals contained in a particular scent; those will also be released into the room.

You can find studies claiming that the emission levels  ofthese airborne candle-derived toxins never pose a threat to people, and maybe they’re right. Heck, it’s not like people are dropping dead because they lit a candle in the bathtub. Then again, nor are people getting lung cancer because they smoked a single cigarette. If any health issues do arise, they’ll likely happen over the course of an entire lifetime from the cumulative effects of chronic, steady usage.

Don’t worry about occasional usage of paraffin wax candles. Especially if you ventilate the room, there’s no real danger in acute, transient exposure. But if you plan on “heavy or daily use” of candles, you’ll want a safer alternative.

Soy wax is one alternative that doesn’t release benzene, toluene, and other petrochemical byproducts into the air. But the wax is almost certain to be derived from GMO soybeans. It’s not an immediate health threat, but if you’re opposed to the industrialization of agriculture and wish to withdraw support of GMO crops, you’ll also want to avoid soy wax candles.

Luckily, a safer and superior alternative that smells better and supports a sustainable industry (beekeeping over fracking and genetically engineered monoculture crops) is available: the beeswax candle. Just make sure your beeswax candle is 100% beeswax, and not some amalgam of beeswax and paraffin (same goes for soy).

I wouldn’t run shrieking from the room if someone lights up a regular candle. On a romantic, candle-lit night with someone special, I wouldn’t pause the foreplay to ask if “those are paraffin candles.” But if you’re going to use candles on a regular basis — and I think that’s a great way to reduce blue light at night and approximate our Primal desire to sit around a campfire at night — beeswax is the safest bet. That the soft honeysuckle scent comes from real natural bee vomit rather than a smell cooked up in a lab doesn’t hurt, either.

P.S. Great to have you aboard the Cert program, Brian! Congratulations!

Hey Mark,

I have a question concerning the sugar listed on food labels and how to account for that when I calculate my daily macronutrients. When I read food labels like those of Quest bars that claim they only have 1 or 2 grams of carbohydrates, yet I look on the wrapper and there are 22 grams listed in the carbohydrate section of the label. They say that because the “other” carbs are sugar alcohols and insoluble fiber, you only have to worry about those 2 grams.

My question is how should I factor this in to my account of daily nutrients. 22 grams or 2 grams of carbohydrates?

Also, are sugar alcohols bad for you (primal)?



Well, let’s break down the metabolic effects of those carbohydrates to determine if we should count them or not.

First, the sugar alcohols. I actually wrote a post about sugar alcohols a few years ago, but let’s look at the sugar alcohol used in Quest in more depth. Quest bars use erythritol, which has 0.24 calories per gram (sugar has 4 calories per gram). For the most part, there’s no evidence that erythritol has negative metabolic effects. Heck, it doesn’t really have any effect at all, good or bad:

Erythritol had no effect on blood sugar or insulin in healthy subjects, with 90% of it being excreted in the urine unchanged. Same goes for diabetics, who experienced no adverse effects on glucose control after two weeks of eating it every day.

Even short term massive overfeeding of erythritol — 1 gram erythritol per kilogram of bodyweight per day for a week — was well-tolerated by people.

As erythritol cannot be metabolized by oral bacteria, studies usually find it to be neutral for dental health. That said, one recent study even found that erythritol was more protective against cavities than xylitol, another sugar alcohol widely touted for its dental health effects. Regardless of which studies you read, erythritol is not going to make your dental health worse.

Some studies find that huge doses of erythritol (50 grams in a sitting) upset the stomach and cause nausea, but most find it has no effect on gastrointestinal response.

As long as you don’t get any weird stomach problems from the erythritol in Quest bars, I wouldn’t worry too much.

Now, the fiber. Quest bars use an interesting type: isomalto-oligosaccharides, or MOS. MOS are a recognized “functional food” with noted health benefits in many Asian countries. They’re used a lot in severely constipated patients, and it appears to be an effective treatment for that condition:

Even if you’re not a constipated elderly man, you can benefit from the generally prebiotic effect of MOS. For instance, bifidobacteria and lactobacillus reuteri — two types of gut bacteria with considerable clinical support — both metabolize isomalto-oligosaccharides. That explains why the long-term MOS study in elderly men increased both bifidobacteria and lactobacillus counts.

Long story short: don’t count the sugar alcohols or fiber as digestible carbs that contribute toward your daily allotment of glucose.

Hi Mark,

I’m a high school student-athlete in track and field. I really want to run while wearing Vibrams, but when I went to track practice with them, the coach called me over and curtly told me to get “real shoes”. So I’m stuck having to wear non-toe shoes. (It would be an ideal world for me to be able to wear Vibrams all day, but if I walk around with them in school my classmates will notice and talk about me behind my back, which I suspect has already happened during the short time I was wearing them at school.)

I want to ask your advice: if you’re in a situation where you MUST wear more conventional-appearing shoes/sneakers *for running*, what specifics would you look for? I wore Vivo barefoot before but the shoe just didn’t cut it for me. I felt like my feet were plopping on the floor.

Thank you!


Assuming your lower body is conditioned to run in shoes as minimalist as Vibrams, look for a few characteristics:

Large toe bed. Vibrams allow your toes to spread of their own volition. They don’t force your toes into preordained dimensions that constrict your feet and alter your gait. The better minimalist shoes do the same by offering a wide toe bed. Try shoes on in person if possible in order to test the toe bed.

Minimal heel drop. If your shoe has “zero heel drop,” both the heel and the forefoot are the same distance from the ground. Bare feet have zero heel drop. Vibrams have zero heel drop. The standard running shoe has a 10 mm heel drop, meaning the heel is 10 mm higher than the forefoot. There are many minimalist shoes running the gamut between zero and 10. Get as close to zero as is comfortable, but don’t put your feet and ankles in a situation they’re not prepared to handle. Don’t think you’re failing or anything if a 2 mm or 4 mm heel drop feels better than the zero.

Everything else you’d like in a shoe. Just because the shoes you found have room for your toes and minimal heel drop, don’t neglect the importance of how the shoe fits, the weight, the traction, and the general “feel” of it on your feet. If your foot’s sliding around inside the shoe, a zero heel drop won’t save you.

Look into Altra shoes, or perhaps the Inov-8s. I have a pair of the Altra Adams. They’re very lightweight, very Vibram-esque without looking like Vibrams. Good for hiking, sprinting, and general scampering about. Neither they nor their female counterparts, the Eve, are available anymore (although it looks like you can buy the Adams through a third party seller on Amazon), but if Altra’s more recent offerings are of similar quality, you’ll be very happy with them. I’ve heard good things about the Altra One.


I was wondering why you put on your walnut oil comment that you would not recommend using it daily. I drink a few tsps a day because it helps with my dry skin. Is that bad?

Thank you!


No, keep at it! If walnut oil is serving a specific purpose for you and your relationship is mutually beneficial, keep using it. My warning against high intake of walnut oil is merely a guideline for the average person, not a rule. Extenuating circumstances (“walnut oil helps reduce my dry skin”) absolutely justify the use. As far as I can see, you’re doing it right:

You’re using it for a specific purpose – to improve your dry skin – rather than because it’s “healthy” (low in saturated fat).

It’s working (it’s actually helping with your dry skin).

You’re taking it cold, not exposing its fragile fatty acids to heat.

You’re (presumably) keeping it in a cool, dark place without heat, light, or air exposure.

You’re doing everything right. As long as it’s helping, stick with it. Just be sure you’re eating fish or taking high quality fish oil. Those omega-3s are still important, especially in the context of your moderate to high omega-6 intake.

That’s it for today, folks. Anyone else got any additional responses to this week’s questions?

Thanks for reading!

TAGS:  dear mark

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 more than three decades 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 flavorful and delicious kitchen staples crafted with premium ingredients like avocado oil. With over 70 condiments, sauces, oils, and dressings in their lineup, Primal Kitchen makes it easy to prep mouthwatering meals that fit into your lifestyle.

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