Dear Mark: Calcium Supplements, Goitrogenic Foods, High-MUFA Seed Oils, and Jogging

Today’s edition of “Dear Mark” covers a variety of topics. We’ve got calcium supplementation – does it make sense and is it safe? Then, I briefly discuss cruciferous vegetables, which are said to have negative effects on thyroid health. Some studies support this, but are they an issue for healthy people? I also look at seed oils high in monounsaturated fats (yes, they exist) and low in the much-maligned polyunsaturated fats, and I discuss their suitability in a Primal eating plan. And finally, a reader asks if jogging is ever okay and, if so, how to do it the right way.

With that out of the way, let’s get to the questions.

Hi Mark,

What do you think about calcium supplements for woman?



Not a whole lot. I covered this a couple years ago, but I’ll expand today.

Most of the literature has found isolated calcium supplementation to be ineffective at its purported job (strengthening bones and increasing resistance to fractures) and way too good at others (increasing the risk of heart attacks, for example). They’ve also found that dietary calcium (the naturally occurring calcium that you might get from leafy greens or dairy) acts differently than supplementary calcium. In one study, supplementary calcium, but not dietary calcium, was strongly associated with an increased risk of kidney stone formation. You don’t supplement calcium for increased stone formation, do you? The latest review says it all: despite the potential role of calcium supplementation in maintaining bone health being “physiologically appealing,” the “latest data” indicate that calcium supplementation is associated with “an increased risk of myocardial infarction and, possibly, stroke,” a risk “that is not mitigated by co-administration of vitamin D.”

Eat your greens, dairy (if you do dairy), organs, and bones. Get some sun. Lift and carry heavy things. If you feel you’re missing some key dietary or lifestyle components, supplement with vitamin K2, vitamin D, and magnesium. Only supplement with calcium if you’re getting the aforementioned factors, too (a recent study reveals the crucial interplay between vitamin K2, vitamin D, and calcium in bone mineral density maintenance). Don’t just isolate a single nutrient. You need all of them.

Hey Mark,

I love your blog and book. I’ve been an active, athletic person for the last 10 years, going from Crossfit to Olympic Weightlifting to just being a gym junkie. I’ve been eating a primalish/paleo diet since around ’03 with the mentality to eat real foods.

I’ve been really enjoying your blog and book and it has gotten me thinking about other dimensions of what it means to be healthy ranging from sleep to sprinting to rest and play. Gone are my days of being a gym junkie, stressing about missed workouts and worrying about numerical goals but more of an emphasis on play, being outdoors and enjoying myself. Subsequently my gym workouts are less frequent, better and a lot more fun. I feel leaner, pound for pound stronger and generally happier.

Regardless, I’ve read a bit lately about goitrogenic foods and their effects on thyroid functions. Some goitrogenic foods include broccoli, kale, cauliflower and cabbage. These cruciferous vegetables are of my favourite foods and are of my staple foods. As a healthy and active 30 year old male, is there a risk of thyroid problems related to overconsumption of my favorite foods or is this mainly a concern for those at risk of hypothyroidism?

Thanks Mark and keep up the awesome work!


Thanks for the kind words, Troy. Emails like yours really motivate me to keep going.

Goitrogenic foods don’t appear to be a huge issue for healthy people. While this article claims that hypothyroidism has been induced in animals by feeding goitrogenic foods, I followed the links and found nothing related. I imagine it’s true; I just couldn’t confirm. It’s definitely true that an 88-year old woman gave herself hypothyroidism and fell into a coma after several months of a daily one-kilo raw bok choy habit, but those are extreme conditions (Have you ever tried to eat over two pounds of raw bok choy? Don’t do it, especially not for several months straight.). More moderate consumption of cruciferous/goitrogenic foods, like, say, 150 grams of cooked Brussels sprouts every day for four weeks, is probably fine for thyroid function.

That said, hypothyroid patients (or those who suspect they suffer from it) should avoid raw cruciferous veggies altogether, instead choosing steamed or boiled (which greatly reduce goitrogenic potential) kale, broccoli, cabbage, and brussel sprouts. Since goitrogens increase the demand for iodine, they should also make sure iodine intake is adequate; a rat study where replacing 1/3 of the rats’ feed with raw cabbage induced alterations in thyroid status and increased thyroid weight after 60 days, even when the rats were given “moderate iodine.” But at “high iodine” intake, these effects were mitigated. They should also make sure not to replace 1/3 of their normal diet with raw cabbage.

Dear Mark,

I’ve been reading a lot of labels on so-called “health” foods that have high-oleic sunflower or safflower oil listed as one of the ingredients. Since oleic acid is the monounsaturated fat so highly touted in avocados, olive oil, and almonds, what is your take on these oils?


They’re actually not terrible. If you stick with reputable companies that cold-press or expeller-press their oils without chemical solvents or high heat, high-oleic sunflower and safflower oils are good in a pinch. They don’t taste like much of anything, making them good for homemade mayonnaise, and they contain vitamin E (if they’re expeller-pressed), making them resistant to oxidation. Furthermore, high-oleic sunflower and safflower seeds aren’t products of genetic modification, if you’re trying to avoid GMOs.

For flavor, I stick with butter, olive oil, coconut oil, or red palm oil every single time, but the high-oleic versions of sunflower and safflower oil are far superior to other vegetable and seed oils. Don’t let this answer be a gateway to vegan “healthy junk food” consumption, though…


Thank you so much for this website. It’s such a tremendous resource of information and inspiration!

I’m sorry, but I’m currently unable to place jogging in a correct context in the Primal Blueprint. Initially, I thought for sure it fell into the Chronic Cardio camp. But then, in The Primal Blueprint, you suggest it for low-intensity aerobic movement (if one is really fit). Does it come down to the heart rate and time spent?

Thanks a lot,


You can boil it down to heart rate and time spent, if you like objective measurements. Certain types of people dig the number porn (particularly the type of person that gravitates toward endurance running, in my extensive experience) and want objective feedback. That’s cool and it totally works, especially when you’re just starting. Ultimately, however, it’ll come down to enjoyment and aptitude. Do you love jogging (or whatever activity it is that you’re questioning)? If yes, then do it (but stop when it becomes a huge drag). Are you really good at it? If you are, then you can probably go harder than most without it becoming Chronic Cardio.

If I were you and I wanted to jog without it getting excessive, I would measure my heart rate and running duration for the first couple times until I began to understand what my targets felt like. So, hit your desired rate, note it, observe yourself, and ask questions. How’s the stamina level? Is this fun? How are your joints feeling? Is this a stressful experience? Am I enjoying myself? How is my overall health? Does my immune system seem to be functioning well? Eventually, you’ll be able to ditch the measurements and go on feeling alone.

I’ve got tons more questions in the pipeline, but I’m always looking for more. Send yours along and I’ll do my best to address them. In the meantime, hit up the comment section. Offer advice of your own, 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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