Dear Mark: Flexibility vs. Mobility, Orange Skin, and Radioactive Matcha

I’m going to keep today’s question and answer session rather brief. I’ll be covering three topics: flexibility and mobility; carotenoderma, or the orange-ing of the skin following ingestion of carotenoid-containing foods; and whether matcha green tea from Japan poses any threat due to radioactive contamination. For the first, I discuss whether it’s flexibility or mobility we want. Second, I explore whether getting orange skin from eating lots of carrots, sweet potatoes, and squash is something to worry about. And finally, I talk about drinking matcha from Japan in the wake of the Fukushima nuclear event.

Dear Mark,

How important is flexibility in achieving real fitness? Most of the yoga teachers I’ve seen are flexible, lean and strong. They’re probably fitter in many ways than people who lift heavy and sprint and many of them only practice yoga for fitness.

I find I’ve gained strength, agility and speed after going primal last April, but I’m pretty stiff and I’m trying to change that as I feel pretty out of shape in my yoga class, while I feel supreme in most of my other fitness classes.

Are you flexible?



Rather than what most people think of when they say “flexibility” – the ability to hold ridiculously contrived poses and lengthen the muscles beyond the point of practical use – I favor optimizing one’s mobility. Mobility is essentially the ability to move freely, easily, and safely, but we can break that up into subcategories.

General mobility describes the ability to safely, freely, and easily move through space-time. It’s walking without a cane or walker. It’s using the stairs, instead of the elevator or escalator. It’s pointing to a place off in the distance and being able to go to there. It’s the kind of mobility that the elderly are most concerned with and everyone else usually takes for granted (until it’s too late, of course). It’s why I walk so dang much.

Local, or joint mobility describes the ability to safely, freely, and easily move your body parts in concert through their full ranges of motion. If you’re lifting heavy things, playing sports, and generally leading an active life, this kind of mobility is crucial – and it goes a lot quicker from disuse or misuse than general mobility. Say you’re at the farmers’ market and you want to pick the best head of cabbage, but they’re all scattered on the bottom section of the display. It’s better to be able to sit in a full squat to make your pick, rather than awkwardly bend over and hold your spine in flexion for minutes at a time. Imagine you’re going for a PR on a deadlift. The better your hip mobility, the better (and safer) your starting position and ability to generate power while maintaining a neutral spine. You don’t want to fight with your body. You don’t want stiff muscles enveloped in tight fascia rubbing up against more stiff muscles in even tighter fascia. Movement should be easy, smooth. When you struggle against your own kinetics because of poor mobility, you lose strength, lose positioning, and put yourself in danger.

Mobility is active and practical. Flexibility, at least the way most people approach it, is static.

Check out my series on joint mobility and be sure to spend some time on Kelly Starrett’s Mobility WOD blog. (And come to PrimalCon! Kelly will be there offering his wealth of knowledge and expertise to all who attend.) Doing so won’t just improve your yoga. It’ll also improve your strength, agility, and speed.


I love orange fleshed foods including carrots, sweet potatoes, yams and pumpkin. However, my usual intake of 1-4 servings a day gives my skin a slight orange hue. I’m all right with the color, as long as it doesn’t turn into a Jersey Shore orange, but could this beta-carotene/vitamin A skin tinting be doing anything detrimental under the surface? How much is too much?



Sounds like you’ve got a case of carotenoderma. In and of itself, it’s nothing to worry about. It won’t cause any harm and it’s not doing anything detrimental under the skin. However, there are two kinds of carotenoderma: primary and secondary. Primary carotenoderma is caused by “excessive” ingestion of carotenoid-containing foods, like the ones you mentioned eating. Secondary carotenoderma is caused by underlying diseases or genetic conditions that impair the conversion of carotenoids to retinol. In secondary carotenoderma, a person could eat normal amounts of carrots, sweet potatoes, or squash and they’d still develop orange skin.

Most cases are primary, and it sounds like yours fits that description. Four daily servings are more than most eat. I wouldn’t necessarily stop, since those are all healthy foods, but you might try limiting your intake to 1 serving a day, or even every other day. If you’re suffering from poor conversion, a single serving a day should still cause orange skin. If it does, you might make up the difference with animal sources of retinol. Things like liver and egg yolks (which you should already be eating) are the best sources around. Of course, eating plenty of liver and egg yolks means your body will likely be replete in retinol, thus reducing the conversion of beta-carotene to retinol. So it goes both ways.

Secondary carotenoderma could also hint at some other underlying health issues. Take a look at your thyroid function and liver health, as hypothyroid patients convert less beta-carotene to retinol and the conversion occurs in the liver.

Would there be any concern of radiation from matcha green tea that comes from Japan? I drink it almost daily.


There have been reports of contaminated Japanese green tea, and last year the Japanese government even banned the use and sale of tea from four prefectures because they tested above government limits for radioactive contaminants: Chiba, Ibaraki, Tochigi, and Kanagawa. Note from this map, however, that both Kanagawa and Ibaraki showed elevated levels of radioactive contamination and that all four prefectures are located near Fukushima. Clearly and intuitively, the closer the prefecture to Fukushima, the greater the risk of contamination. From what I was able to find, most matcha in Japan is actually grown and produced in more distant prefectures, like Kyoto, where the city of Uji is well-known for matcha tea production, or Aichi, which according to both this source and this source has passed the radiation tests. Consult the maps and search for matcha green tea from prefectures that either tested low in radiation or are located far from Fukushima.

Since we know that drinking matcha tea results in greater absorption of green tea antioxidants and amino acids than simply drinking tea made from green tea leaves, I imagine you’d also be absorbing more of the bad stuff (if any is present). You might consider switching to regular green tea leaves for awhile to allay any remaining concerns.

That’s it for this week, folks. I told you it was a short but sweet one. Keep the questions coming in and be sure to leave a comment! 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 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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