Dear Mark: Cruciferous Vegetables and Hypothyroidism, Sprint Frequency, Protein Sources for Orthodox Lent, and Saunas

Cruciferous VegetablesFor today’s edition of Dear Mark, I discuss the connection – if one even exists – between cruciferous vegetables (and their goitrogens) and thyroid function. A theoretical interaction exists, but should this impact your decision to eat steamed broccoli? Next, I explain why I recommend one, maybe two days of sprinting a week, in contrast to the exercise studies that often use 3 or 4 days/week sprinting programs to great success. Then, I give a few tips for a person wondering about getting sufficient sources of Primal protein while on an Orthodox Lent fast. And finally, I explore the potential health effects of saunas.

Let’s go:

I read a report on kale and other cruciferous vegetables causing hypothyroidism if eaten too often.

I believe in moderation but this is the first time I’ve heard this. Can you touch on this subject?

Here’s the article.

Thanks, Mark.


I almost hesitate to discuss this, because I don’t want people worrying about their broccoli intake or experiencing anxiety whenever kale is served. Yes, cruciferous vegetables, which include kale, broccoli, cauliflower, cabbage, kohlrabi, mustard greens, Brussels sprouts, and bok choy, among others, do contain compounds known as goitrogens. Goitrogens reduce the amount of iodine absorbed by our thyroid glands, and at really high levels can actually prevent iodine from being incorporated into thyroid hormone altogether. Animal studies have shown that large doses of cruciferous vegetables like cabbage can interfere with thyroid function.

Here’s the thing, though. Cruciferous vegetables are only a problem when they’re:

  • Consumed in ridiculous amounts – like the lady who put herself in a hypothyroid-induced coma from eating kilos of raw bok choy every day, or the rats who ate a 33% cabbage diet.
  • Consumed raw – cooking deactivates many of the goitrogens in cruciferous vegetables. Steaming reduces goitrogen content by around 30%, boiling and keeping the water by 65%, and boiling and dumping the water by 90%.
  • Consumed by people who don’t eat any iodine – eating sufficient iodine provides a buffer against the goitrogen effects of cruciferous vegetables; as long as you eat sea vegetables, pastured egg yolks, and seafood, you should be getting enough.
  • Consumed by people with established thyroid problems – people with hypothyroidism are more susceptible to goitrogenic foods (but that doesn’t mean you should avoid them; just don’t go overboard).

So, a raw vegan juicing several kilos of raw Brussels sprouts, bok choy, and kale on a daily basis might have thyroid problems (in addition to fascinating bowel habits), while a Primal eater having a side of steamed broccoli, cauliflower, or cabbage with a steak a few times a week will be just fine. Even a raw kale salad now and then is fine (but probably not a pound’s worth every day). One study looked at the effects of raw broccoli sprouts, which are extremely rich in the goitrogenic compounds people are worrying about, on thyroid health in humans and reported no abnormal findings. Don’t worry too much about cruciferous vegetables. They’re good for you and only harmful in ridiculous situations where most reasonable people will never find themselves.

One quick note: Pregnant women early on in the pregnancy – when thyroid function is most important and thyroid hormone requirements are especially high – may be more sensitive to goitrogens. This usually coincides with taste aversions, so eating too many goitrogenic vegetables is usually hard to do. But it’s worth keeping in mind.

Hi there 🙂

Okay. I’m curious. Most of the studies I’ve read (some of which Mark quoted in his most recent article) put HIIT and Tabata training at approx. 3 – 4 sessions/times a week. Mark advocates to sprint “once in a while”, or once a week in his PB Fitness Book (as per the fitness logbook). So… is sprinting 3-4 times a week too much? would it be less effective and closer to a “chronic cardio” type deal? All the gains from the studies I’ve read are from individuals participating 3-4 times a week for about 12 to 16 weeks.

Thanks! 🙂


Great question. The thing about those studies is that in order to exclude any confounding variables, they generally forbid participants from engaging in other exercises. So in a HIIT study, you’ll just do HIIT and nothing else on the side. You won’t lift weights, or go on hikes, or walk 10,000 steps a day. You’ll be focusing on HIIT and HIIT alone so as to isolate the effects of the experimental condition. The absence of other training coupled with the total dedication to the program allows adequate recovery.

If you weren’t doing anything else (like the study participants), I’d say you could get away with three or four sprinting or HIIT days a week. I think, though, that optimal fitness is achieved through a more well-rounded approach that includes lifting heavy things, play, lots of slow moving, and sprinting (or HIIT). All those activities require recovery time. We can and do learn from fitness studies, but in reality we can’t just take what studies do wholesale. We would fail, or be required to sleep twelve hours a day, or eat 5000 calories.

Another factor to consider: many of these studies use students because they tend to have more free time than working adults. More free time also means more recovery time and (usually) less psychological stress that impacts workout recovery. They’re arguably a better way to study the effects of a training program in otherwise “pristine” people without lots of confounding lifestyle factors.

With regards to sprinting in particular, I usually dedicate an entire day to it. If I do workout in addition, I treat sprinting like a really grueling lower body workout day. I’ll sometimes lift the same day as sprinting, but I’ll mostly stick to upper body lifts like pullups, dips, or pushups.

I had a question I have not seen answered. I am an Anglican who has adopted some Orthodox practices. In the old church tradition there are fasting and abstinence seasons and days. Lent is the longest and the tradition is to abstain from meat, oils, and dairy for 40 days plus weekends while reducing meals. Food is to be simply cooked or eaten raw if possible.

This does not easily fit with the Primal Blueprint. Any suggestions about what to do during those times? I plan on using tempeh as a protein source but lentils are also an option. It will be hard to keep carbs down without eating a lot tempeh and Natto during the time. Is seitan a solution?


Tempeh is a “pretty good” vegetarian source of protein. Yeah, it’s soy, but fermented soy, and the fermentation process reduces phytic acid and deactivates the lectins.

Natto is also advised. Those who can get past the interesting texture, difficult odor, and curious taste to reach the numerous health benefits (including a whopping dose of vitamin K2) are often pleased they made the effort.

And as far as legumes go, lentils are probably the best and least offensive option. They’re pretty digestible after about 8 hours of soaking and they’re decently nutritious.

As far as I know, shellfish are still allowed during Orthodox Lent, right. If that’s the case, go for those guys. Mussels, clams, shrimp, scallops, lobster, crab, and oysters can easily take care of any animal protein needs. It might be a bit more expensive than you’re used to, but you can’t go wrong with shellfish, some of the most nutrient-dense foods around.

I would skip seitan. It’s basically a block of pure gluten. I suppose it’d be okay if you’re totally free of gluten intolerance or sensitivity, but it’s more common than many people assume and I wouldn’t want to tempt fate and find out the hard way.

Are eggs allowed? If so, eat some of those.

What else can John eat, readers? Maybe some alternative protein powders? If you can’t do whey, look into some “complete” (meaning a full amino acid profile has been attained by blending different plant protein sources) vegan protein powders for the time being.

Hi Mark, keep it up. You are doing God’s work, and have been a blessing in my life.

Wondering what your thoughts were on the idea of “cleansing” and also steam/sauna. Is there a primal way of looking at these? Health benefits?


Rev. Josh

I’m always curious about those near-universal human traditions with extensive histories. People generally don’t just do stuff for the heck of it. You dig deep enough and you can usually find a kernel of truth there, some health benefit at least partially confirming the tradition’s efficacy.

The sauna is definitely a near-universal human tradition. In the Americas, there are the sweat lodges of North America and the temazcals of Central America. Scandinavia is known for its saunas, particularly Finland. Russia has the banya, Turkey the hamam, and ancient Rome the laconium. People from all over the world have been enjoying the heat for thousands of years, but are there actual, documented benefits to sweating it out in a sauna?

Muscle recovery: Steam saunas appear to improve muscle recovery following exercise to exhaustive failure.

Stress reduction: Most people intuitively know that saunas are relaxing, but they legitimately reduce cortisol over the long term. The sauna experience itself acts as an acute stressor, however, spiking cortisol and heart rate and adrenal hormones – but only for a short time.

Toxin clearance: Contrary to what cynics might give as a knee-jerk response to any question involving the word “toxins,” it appears that there might be something to the idea of “sweating out the toxins in a sauna”:

Any downsides?

Male fertility: Saunas are hot, and heat can negatively impact male fertility. One trial found that sauna usage impaired spermatogenesis in men with normal fertility. This effect was transient and reversible, however.

Heart trouble: People who’ve recently had heart attacks, or who have unstable angina pectoris or severe aortic stenosis may want to avoid saunas.

Exposure to carbon monoxide: Wood-fired steam baths, like some temezcals in Latin America, can produce massive amounts of carbon monoxide, a known toxin.

For the most part, saunas are safe, and they may be extremely good for you. Even if you “just” enjoy them after a hard workout or as a way to relax, I’d say there’s definitely something to them. The health benefits of relaxation and pleasure-seeking are not to be understated.

That’s it for today, folks. 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 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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60 thoughts on “Dear Mark: Cruciferous Vegetables and Hypothyroidism, Sprint Frequency, Protein Sources for Orthodox Lent, and Saunas”

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  1. On the side, I coach injury prevention at a CrossFit gym with people who go more than 3-4x/week and who exert themselves much more than Tabata or HIIT work would. What helps? Increasing sleep, carbohydrate intake, overall food, and listening to your body and you should be fine. If you ignore those things, you might as well ignore training.

  2. Mark

    Can you clear up where your weekly 100% intensity tempo ride fits into the suggested “well-rounded approach that includes lifting heavy things, play, lots of slow moving, and sprinting (or HIIT)?” When I heard that you conducted that, I became slightly confused!

  3. Saunas, hot springs, mineral baths are one of the best things you can do for yourself. The skin is a giant organ. The hotter-than-your-body conditions literally pull water through your bloodstream and out of the pores of your skin into the atmosphere. Cleans out all the crap from bottom to top. That’s why you feel so light and refreshed after a good trip to the sauna or mineral baths. Its osmosis!

    For the nerds:

    1. Regarding saunas, one of the possible causes of spina bifida, a birth defect, is overheating the body. The most critical time to avoid overheating the body is during the first few weeks of pregnancy, before the woman even knows she is pregnant. (and taking folic acid/folate prior to getting pregnant is also advised to prevent spina bifida)

      1. If that were the cause, spina bifida would be more common in Finland, Russia and Turkey, as well as amongst the First Nations with a sweat lodge tradition. However, this is not the case. According to wikipedia:

        “The highest incidence rates worldwide were found in Ireland and Wales, where three to four cases of myelomeningocele per 1000 population have been reported during the 1970s…”

        As far as I know, there is no sauna/sweat lodge tradition in either Ireland or Wales.

  4. Wow, great point about Lent. Pre-Primal/Paleo I relied on pizza, grilled cheese, etc. to get me through Lent. Now it’s a little more challenging, but in my tradition (Roman Catholic) we can have fish so I guess I’ll be okay. We also only abstain on Fridays.

    1. Our priest also confirmed that bone broth is allowed as well, since only the flesh is part of the fast.

  5. I live in Ethiopia, where Orthodox fasting is taken very seriously. The pre-Easter fast started today (after a weekend of a LOT of grilled mutton – the roads were full of discarded sheep heads and goathides drying in the sun). Here, fish is allowed during the fast (although not eggs). There are also a lot of chickpea dishes. I know, chickpeas (garbanzo beans) are not primal, but are up there with lentils as a reasonable alternative in my opinion (if your don’t get an adverse reaction, of course). I think that when the chickpeas are dried out, ground to powder, and then added to spicy, buttery curries, they contribute a bit of protein without too many harmful effects (could be soaked first, too). Lentils, split peas and lots of spinach dishes feature at this time of year.

  6. I guess most sprinting studies are done on beginners. Unfit person can’t produce a lot of force and although psychologically might not be able to push all-out if not used to high effort activities. So workout doesn’t require a lot of recovery time. More fit person becomes, more stressful become high intensity workouts and body needs more time to recover. What works for first 16 weeks or less will not be sustainable in long term and will lead to overtraining.

  7. Re: Lent–what about algae? There are supplements, powders, and shakes, as well as dried kelp and seaweed snacks. Also, if sesame seeds are permissible, they contain a whopping load of protein by volume.

    Now for a turn to the wild side: bugs, worms, and insects of all kinds–they’re protein too, but probably not your favorite kind, right?

    Then there’s nuts and nut products: almond milk, almond cheese, coconut milk, coconut yogurt, coconut wraps (Paleo wraps), as well as seed/seed products. Even coconut meat has some protein in it.

    Alas, potatoes may not be strictly Paleo or Primal, they do contain protein, as well as avocados. If shellfish can still be eaten, here’s a fantastic avocado shrimp boat recipe:

    Your amount of foods needed to replace what meat provides will rise, of course–vegans also have to take in more “alternate” foods to replace the missing meat protein. But this is temporary, and you can always do a Whole30 (or some other detox) at the end of it.

  8. I’m glad I follow Grok’s religion, which allows any edible food 😉

  9. Perfect timing just had a client ask what to eat for Lent. Just saved me a lot of time thanks!

  10. Russian Orthodox here. Shellfish can be eaten without restriction during Lent (and other fasting seasons). Protein has never been the problem. For me the issue has always been getting quality fat. Well, maybe the monotony of shrimp, clams, scallops, etc., over and over again, in every possible combination and permutation. Thai curries with coconut milk and shrimp are a good option. I would certainly appreciate any suggestions for decent fat sources, although I already use coconut oil a great deal. Frankly, given the near complete incompatibility of the primal / paleo paradigm with Orthodox dietary proscriptions, i have adopted the practice of eating less and fasting more during Lent, sometimes using it to to simulate deprivation / starvation. My bottom line from the standpoint of diet is that Lent is an environment I have to survive in for six weeks. Afterwards, I compensate!

    1. I would suggest avocado. I eat an avocado a day 5-6 times a week. I usually make a guacamole (mashed avocado, 0.5 mm sliced red onion , lemon/lime juice, salt and a pinch of chipotle/paprika) and it works really well for me. It takes only a couple of minutes to prepare and I have my dedicated set of tools to work even faster.

      1. I’m right there with ya on the avocados. A ripe avocado mixed well with a couple of chopped hard boiled eggs and a bit of dijon mustard makes a REALLY nice “mayonnaise,” that compliments many foods, including my favorite: smoked kipper salad (smoked kippers fork mixed with avocado mayo). One of these days I’ll try as a “tuna salad” for the kids this way… The “mayo” could even be blended for a really smooth consistency. It’s really the egg yolk that makes it work, but I like the whites in there, too.

    2. +1
      The Lent list and the Primal list don’t have much in common except intermittent fasting.

  11. As far as I know (and I’m not an expert), Russian Orthodox church allows vegetable oils on Saturdays and Sudays during Lent. Fish is allowed during church holidays which coincide with Lent. Funnily enough, caviar is allowed on certain days. Eggs are definitely prohibited, since Lent is generally about not eating animal foods. But people who feel sick or weak are usually allowed to follow less strict diet.

    As for shellfish, a couple of years ago I’ve read an entertaining discussion on a Russian Orthodox blog. Apparently, Russian church does not have official recommendations about shellfish (unlike Greek Orthodox church which allows them afaik). There is a lot of uncertainty – some priests think these foods are ok, others think they should not be allowed, because they are still animal foods, and also many see them as luxury items eaten for their taste, and you are not really supposed to enjoy your food during Lent. 🙂

    So, I guess, if you want to follow Orthodox Lent, you should pick the Orthodox tradition with best dietary practices. 🙂 I know, I’d definitely prefer Greek if I had too…. shellfish… mmmm 🙂

  12. This website www (dot) antiochian (dot) org/fasting-great-lent has some good information on the Lenten fast. Even if you’re not Orthodox or Antiochan, it’s helpful to know what foods are proscribed, and why.

    The fasting practices of modern RC’s is too watered-down so I follow the Orthodox tradition. I go off the Primal rez during this time, eating more legumes soaked and simply prepared, and even bread (my own sourdough).

    An Orthodox fast is downright vegan except for the permission to eat any invertebrate sea animals – shrimp, mussels, clams, etc. are all permitted. Olive oil is not (it is considered a luxury item and therefore proscribed except on Sundays or feast days that fall during Lent). Vegetable oils are permitted, so you have an impetus to begin using more coconut oil in your cooking.

    All meat, vertebrate fish, poultry, eggs, and all dairy products are forbidden.

    Lent is the time when Christians are supposed to pray and reflect on their salvation and why Christ came to the world, and how sin distances us from God and heaven. For the non-Christian or non-religious people out there, I urge you to consider what Lent means in the greater scheme of natural rhythms and patterns. The end of winter and the coming of Spring is a time for rejuvenation, not just for us but the animals. Milk cows need to feed their young, chickens are ready to lay again (as their egg-laying is a light and nutrient dependent endeavor), young animals born in spring need time to grow and suckle and graze before being slaughtered. Reproduction must be allowed to occur if we are to eat and enjoy animal foods, no? And Spring is a time for that.

    By following a period of abstinence from animal foods, we let nature do what it must to further the various species in their dance of life. I know we’re not doing historical re-enactment here, and that modern agriculture and refrigeration mean we can eat anything, anywhere, anytime, and all the time. But if a large part of your reason for eating Primal or WAP style is to get more in touch with the rhythms of nature and to become less dependent on Big Ag and modern preservation technology, consider following some form of Spring fasting, to get you in touch with those natural rhythms, and give the animals a break and time to get their own systems up to speed, fully nourished, and ready to share their gifts with us once again.

    1. Except it isn’t spring in all parts of the world. I always find it intriguing that these religious traditions are meant to be carried out according to the calendar, even though they probably did originate from seasonal factors. Logically, we should do lent in August/September if it is about seasonal environmental care, but that doesn’t fit with the religious dictates.

      1. That’s what I was going to say Lyn… primally speaking in my neck of the woods we should be gorging in preparation for winter and scarce food sources…

      2. Lyn, I think you misunderstood the whole of Amy’s response. The point of the Orthodox Fast is not one based on seasonality or enviromental concerns, and it certainly did not originate from seasonal factors. Maybe that is true for other religious traditions you may have in mind, but Orthodox Lent is based solely on the person of Christ and thus transcends any notion of seasons. Her musing on the environmental aspect was for the non-religious to consider (as she noted).
        Wishing a fruitful Lent to all those who will be partaking!

        1. I don’t think Lyn misunderstood at all – Amy’s writing clearly tries to relate the origin of such religious dietary guidelines to the seasons.

          If such dogma is purely for religious reasons, and the relationship to seasons is purely coincidental, then there was no reason to even mention seasons.

        2. John: Amy clearly states that ‘for the non-Christian or non-religious’ person, she was trying to frame Lent in terms they could possibly be interested in relating to; ie seasonality. I don’t think she was attempting to claim there is a fundamental seasonal connection to Lent, because theologically there isn’t one. I was simply trying to correct Lyn’s ‘intriguing observation’ that Lent probably originated as a seasonal observance but then due to ‘religious dictates’ is now illogically relegated to a simple date on a calendar type observance.

      3. Very true. I live in the Southern Hemisphere (South Africa) and find that I am usually out of sync with the normal religious/traditional feasts that we inherited from Europe. Christmas is hot, not cold and wintery. Easter is autumn and not spring, generally cold and often wet. There are one of two things to do – celebrate Christmas in June or July and Easter in September, or try to adapt as much as you can the original ideas to your own weather.
        By the way, not meant as a criticism, but I often find that health blogs tend to forget that half the world has the opposite seasons to North America/Europe and so the suggestions are often way off if you live in the South.

        1. Nina, those religious festivals originated as pagan spring rituals. The meanings behind it are still there but the Christians just added Jesus to it. Its a celebration of the Equinox which is tied to all of those those things mentioned, life an rebirth. These were going on a long time before the Christians came along

    2. Interesting to hear some of that history.

      But why refrain from eggs if my local farmer up the road has a surplus? Or milk? Or olive oil, if my orchard is full of olive trees?

      Or, for that matter, anything which is available from a responsible steward of the land?

      Though perhaps some of the religious dietary guidelines were derived by people living close to the land, to use that as an argument to abide by them today is just as silly as promoting blood letting or refusing antibiotics.

  13. Another question on Orthodox lent- is there a prohibition against the whole animal, or only muscle meats? If so, gelatin and bone broths may be a solution.

    1. I’m pretty sure all animal foods period, except for shellfish, are pretty much not allowed. At least for the orthodox versions. So gelatin and offal would be out.

      Bone broths too.

      I believe dairy and eggs are also frowned upon during Lent unless you are seriously sick and have a medical reason for needing to include them.

  14. Re: fasting and abstaining I’m Roman Catholic, and years ago I was vegan. Abstaining from meat meant absolutely nothing during those years. Over time I’ve become Primal. Last year I took a hard look at the idea of fasting and abstaining, the whys and wherefores, and prayed on what made sense between me and my God. (Primal sure has taught me not to follow rules just because they’re rules!) The approach that I take–actually my entire household–is that we go hard core Primal for Lent. While I enjoy my grass fed beef, even on Fridays, there is absolutely no flour, sugar, bottled salad dressings, occasional french fries….and many other things.

    What I discovered is that there is more fasting and more abstaining, more thoughtful deprivation, going on this way than in following the traditional rules of my faith.


    1. I agree with you and it’s also my plan for this upcoming lent. I’m actually non-religious but was raised Catholic and always have loved the Lenten season. I try to use it as a time of reflection and to better myself in all ways.

    2. My understanding of lent is that it’s a time to simplify to allow contemplation. Giving more thought to your food so that you can find something to eat that is primal enough and adheres to the letter of the law regarding food restrictions seems to go exactly against the spirit of lent.

      Reduce your food through fasting and smaller portions and keep your meat and veg preps simple. Then you will have time to reflect and pray without distraction.

      1. Well, described that way, I suppose it does go against simplification. But in our home, it indeed ends up being a simpler way to eat during Lent.

        In following Primal, including the 80/20 aspect, we keep flour and sugar and bottled dressings in the house. And other foods that aren’t Primal. They are occasional indulgences, and we enjoy them. During Lent, I put those all away. I might desire to make a roux for gravy for the pot roast, but there’s no flour so it’s simple: we don’t have it. Feeding four people with very diverse tastes, who are used to my cooking (I’m a former pastry chef), is by no means a simple endeavor. But during Lent, we have far fewer ingredients to choose from. During the year there are usually four or 5 salad dressing in my fridge at any time, some Primal, some not. During Lent, we have only olive oil and a few vinegars.

        Fasting and smaller portions isn’t really prayerful for someone like me who already fasts regularly and doesn’t eat much. Not a single potato chips or even one packet of Splenda for the entire 40 days….that’s sacrificial (for me at least 🙂 The ability to share my example with my children (who are too young for traditional religious fasting), and being able to give them black and white ‘you may eat this but not that during Lent’ is a help to my family. I suppose if I lived alone I might take a different approach, but I don’t. This works for us.

  15. Students have free time than adults…? My god, I hope you’re very very wrong about that. I’m looking forward to the day when I’m no longer writing research papers, reading textbooks, and studying for tests every day of the week. I was counting on having enough time to work out when I graduate. At the moment, I only have time for 4 hours of walking a week (walking to and from school), one or two strength training sessions, and maybe, MAYBE, a sprint session.

  16. I was surprised to see the information about crucifers and goitrogens. I’ve been on a low dose of levothyroxine for probably 15 years. My HCP prescribed it because my blood levels were a little off, even though I never had symptoms of low energy, dry skin, thinning hair and being overweight. I wasn’t really surprised, though, as my mother and most of her sisters apparently have underactive thyroids. (I’m still not convinced I need to be on meds.) Anyway, I’ve recently gotten stuck on eating a raw cabbage salad that I love. I make a batch each Sunday and eat it throughout the week with my lunch. I also eat a lot of broccoli and cauliflower, and frequently eat Brussels sprouts. I haven’t noticed any changes that have raised any flags, but when I read the article and started thinking about the vegetables I eat, I realized I eat a lot of crucifers. I’m wondering now if I should cut back.

  17. Is there a difference in health benefits between dry saunas and steam baths? I can’t breathe in a dry sauna, but I adore steam. I’ve even thought about outfitting my shower with a steam generator.

  18. Practicing Orthodox Lent here. The spirit of the fast is important. So if the official rule says no meat/fish/dairy/eggs/olive oil, it is kind of beside the point to turn interpret this in a legalistic manner and have, for example, luxurious lobster dinners with margarine instead of drawn butter. I’m even a bit iffy about substituting oils like coconut oil.
    I have found that this period acts as a reset: the physical is connected to the mental, and somehow after the fast, I just feel more healthy, mentally and physically.

  19. Mark, I am confused. How do you devote a whole day to sprinting?

  20. Saunas make sense. I’ve taken my temperature before and after. Forty minutes yields a rise of five degrees. On several occasions I’ve gone in feeling like I had a cold coming on and felt my immune system shut down half an hour later like a switch flipped, as if to say, “my work is done.” If a fever is nature’s way of killing germs with heat, why wouldn’t a sauna work as well?

  21. Many moons ago I worked out at a gym that had a hot tub and a swimming pool. When I had time after my workouts, I would take a dip in the hot tub, and then swim a few slow lazy laps in the pool, maybe even repeat that once or twice. The hot tub/pool time significantly decreased my recovery time from my workout.

  22. For what it’s worth, my n=1 on cruciferous vegetables: I have a dx of thyroiditis and in the beginning (about four years ago), my PCP pointed out this suspected link to me with the same qualifiers Mark expresses.

    Eliminating these vegetables would significantly change what is on my list to eat (hello cucumbers!) but I did try it for a while. Absolutely no change or improvement. So I eat them several days a week in normal quantities.

    Bonus comment: My PCP also suggested supplementing with selenium, noting scant evidence but yet evidence. I have been doing that and when I stopped out of curiosity if I was wasting effort, I noticed a flare in symptoms. My diet has a healthy amount of selenium too but the supplement has been apparently useful to me (again n=1).

  23. as a russian orthodox whos grandma and are mother very much into it ive been exposed to such facts told by priests/religious books:

    traditionally monks survived on bits of dried bread soaked in water/ raw veggies, prayers and spiritual support of god ..but we aint monks..we work/study/train.. every day life and routine goes on..

    for everyday folks in russia base of lent diet is wholegrains (rice,buckwheat,millet,barley), lentils and beans, pickled vegetables in winter, fresh veg/fruit in the summer …russian orthodox religion definitely allows oils for lent, no molusks (only on fishy holidays)

    so guess protein requirement is met through wholegrains/occasional fish intake on church holidays

    for more acitve/sick people priests advise to be less strict – include fish/eggs/diary while trying to at least obstain from meat

    me thinks lent is not traditionally if your going primal ..guess you better look into adapting your diet during lent and allow for fish/eggs etc..the main thing is not to forget the true value behind lent..its nto a diet after all its a did of spriritual matter..

    just my thoughts!

  24. Interesting posts.

    The Roman Catholic tradition was that you make things harder for yourself in those periods. You remember Jesus fasting for 40 days in the desert. So if you believe in it and are doing it for religious reasons then the aim is for something unpleasant. It would be ridiculous to find much nicer foods for example like luxury fish just because meat were banned. So you will pick what you hate and perhaps makes you feel bad (this of course illustrates much of what is wrong with most of the religions).

    You could also keep it unpleasant by having more intermittent fasting, although if all this is just to make you feel better or to lose weight (Lenten or Friday fasts) the church would say go out there and visit some elderly neighbours or do other good works instead of messing around with diet, as that is the spiritual aim, not to indulge yourself. Make sure the fast does not become a self indulgence or for your own benefit as it were.

  25. The first part about goitrogens makes me wonder about the salad mix my wife and I have been eating lately.

    It’s a ‘kale mix’ we buy from Costco that has kale, cabbage, radicchio, and brussel sprouts. On average, i eat close to 5 cups of it a day during lunch (at least thats the size of tupperware i pack it in) with a handful of walnuts and berries. I don’t eat a lot of seafood at the moment, but i do usually have 8-12 egg yolks (not pastured) a week, so i have no idea if I am getting ample iodine.

    What would be considered a ridiculous portion in the context of this post.

  26. Hi Mark-I recently (this past week) started primal eating. I am 78 yrs old, 5’5″ and weigh 118 pounds and do not want to lose weight. I’m going primal because I have a long history of IBS, sinusitis and recently lack of energy. I know you had some of these problems. My IBS (every morning) is characterized by getting the “runs” and so I often take Imodium. I feel much better by the afternoon. I am wondering if all these veggies and fruits that I am now eating could be exacerbating the problem. Help!!!

  27. As an RC, I would like to remind that Sundays through Lent are considered feast days and one does not need to fast. So on those days you can build up your “stores” for the week 🙂

  28. I have been reading wheat belly recipes and shirataki noodles have been promoted. Are they primal?

  29. Greek Orthodox here. For the past two Lenten periods my husband and I have gone strict paleo, including no sugar (honey, maple syrup). We eat simple meals and it is a time of contemplation and spiritual focus for us. We’re not fans of the “traditional” fast for a number of reasons. Also, Lent isn’t just about robotically fasting from food items.

  30. I am roman catholic, and my parents are orthodox. Lenten for me is about giving something up, to connect with the sacrifice. But not a woe is me sacrifice but a private contemplation. I am one month of going paleo, and I am not as legalistic about it. I will fast, and do fish on Fridays. Paleo had already removed the stuff I would traditionally give up ( coffee, sweets, flour) I’m getting up an hour early to read and meditate and contemplate.

  31. Any word on cruciferous veggies & blood clotting? My daughter at age 17 developed a blood clot due to a clotting disorder. She too was told not to eat too much of any of these veggies.

  32. Hey Mark,
    First of all, I love your website and your articles.
    Second of all, I am having some serious thyroid problems because I unwittingly ate goitrogenic foods in high amounts, for an extended period of time. I mean pounds-per-week of crucifers, nuts, spinach, peanuts and other stuff, for over a year.
    My health has been suffering, my hair is brittle and falling out, my face is puffy, my neck is swollen, I have severe insomnia and fatigue, I have a diminished sex drive and I am having some bowel problems that led to an ER visit.

    I was wondering if there are foods that can retroactively help me get my health back to stasis or if I pretty much have to stop eating [or drastically reduce] them for a while, up my iodine and ride it out. I have been eating sheets of nori alongside my regular meals, in the hopes that it will help me feel better, but so far no such luck.

    Your input would be much appreciated, thanks again for your highly informative articles and videos.


  33. Hi there!
    I’ve read your book(s) and it all makes sense to me, though last night I ended up watching What The Health and am now a bit weary of the sources of meat. They did not go into too much detail on free-range sources, but they did mention salmon (and other fish) are “sponges for toxins.” What are your thoughts on the documentary, and how to navigate with both schools of thought; avoid meat + be primal.