Dear Mark: Carb Concessions, Nitric Oxide, and Chronic Cardio

“Winter is coming.” (Albeit, a Malibu winter, which is closer to a somewhat mild spring in other parts of the country, so I can’t really complain; I just wanted to use that quote contextually.) Yep, I’ve been catching up on “Game of Thrones.” Dang fine show, but now the long slow agonizing wait for the second season commences. Anyone else watch?

Anyway, it’s Monday, which means it’s time for another round of Dear Mark questions and answers. I field one from an ecologist soon to be working out of Nicaragua and worried about making dietary concessions and balancing Primal eating with cultural faux pas. Next, I discuss nitric oxide supplementation, and whether there’s a better way than taking it direct. Finally, I explain how one determines the chronic cardio-ness of an activity.

Let’s go.

Hi Mark

I’m in the process of switching over to a Primal [Blueprint] diet, and I have a question that might be good for your “Ask Mark” posts.

My upcoming challenge is a 3-week trip to Nicaragua, where I do a lot of field work (I am an ecologist). While they have THE BEST grass-fed beef there (I’m drooling just thinking about it), it is also going to freak people out that I will be turning down rice and beans (fried in trans-fat laden vegetable shortening, no less).

I’ll probably have to make some concessions — when a campesino offers you a plate of hard-won beans grown by the family, it doesn’t sit well to turn your nose up at it and talk about carbs! But I’m also wondering if some of the other “carby” choices might be acceptable in a pinch. Specifically, plantains (eaten both in green and ripe forms, the latter usually fried; green plantains may be boiled or fried) and yucca (usually boiled) can commonly turn up on the menu, and asking for extra boiled green bananas might make up for the faux pas of turning down the rice.

Another thing likely to turn up at every meal — corn tortillas! You’ve discussed the detrimental effects of straight-up corn in your blog, but the tortillas are made from corn after it has undergone a process of soaking in an alkaline solution (known as nixtamalization). This process is widely known to improve the nutrient profile of corn, but I’m wondering if it similarly removes some of corn’s “anti-nutrients”?



First off, you’re right to recognize that “Primal purity” has to go out the door in certain instances. At a buffet dinner for work? Sure, go ahead and politely pass. Wax poetic about why you aren’t eating something. Get into it with a vegetarian. But when a host family offers the clothes off their backs or the beans from their pantry, you generally accept. Definitely make those concessions when they’re necessary – provided you don’t have serious digestive issues with particular foods that you know will cause problems. And no one says you have to finish everything that’s on your plate. Remember – 80/20.

Yucca and plantains are good choices. Obviously, go for the boiled ones when you can, especially if they’re using “trans-fat laden vegetable shortening” to fry them, and rest assured that these are “safe starches.” In fact, yucca root (also known as cassava), is the third most-eaten source of starch in the entire world. It does contain high levels of cyanide, but proper processing totally removes all traces of the toxin. And remember, rice isn’t all that bad, either.

Nixtamalized corn is also a fair concession. Corn can come with mycotoxins, a category of toxic molds that often grows on cereal grains or legumes that have been stored improperly. In years past, I’ve written about peanuts and afltatoxin, one of the more notorious mycotoxins dangerous to humans as well as animals. Luckily, nixtamalization destroys the bulk of mycotoxins present in the corn before processing.

I’ve searched but haven’t found anything regarding your feelings of taking nitric oxide as a supplement prior to working out. CNN is pushing it for older guys (I’m 45) as similar in effect to steroids but healthy. Thoughts? Thanks for everything. I hope to post a before and after story soon.


Much has been made of the ability of nitric oxide to increase performance and stamina, especially in high-intensity activities. It’s legit. In one recent study, nitric oxide in the body reduced the oxygen cost of exercise, improved stamina, and increased performance. Nitric oxide literally widens blood vessels and arteries, thus increasing blood flow to tissues (and the amount of nutrients that blood carries to those tissues). It even reduces blood pressure, and an earlier study had extremely similar results in cyclists. So it appears to work.

But there’s a catch: neither study used nitric oxide supplements. Instead, they used nitric oxide precursors, or substances that the body uses to produce its own endogenous nitric oxide. The earlier study used beetroot juice, a good source of nitrate. Nitrate is converted into nitric oxide in the body. In the second study, researchers increased nitric oxide by administering L-arginine, an amino acid precursor to endogenous nitric oxide production. There is very little evidence that direct nitric oxide supplementation increases exercise performance, so I’d save your money and eat beets or take arginine supplements. Nitric oxide may work directly, but the precursors are proven to work and are likely far less expensive. I’m reminded of the glutathione situation, wherein supplementing with precursors is far more effective than taking the thing itself.

If you do a before and after story, I’d be really interested in hearing whether trying to increase your own nitric oxide production helped your performance.

Oh, and I’ll have you know that 45 ain’t old!

Dear Mark,

I think you’ve addressed this in the past but maybe not directly. I’m wondering just what you would consider “chronic cardio”. I know the drudgery of the treadmill or the elliptical. But I’m wondering about this… when I’m able, and sometimes that’s every day for weeks or months at a time, I ride my bike to work. It’s a healthy ride, 15 hilly miles each way. Takes about an hour each way. So that’s chronic, right? Two hours a day every day. But it’s biking and it’s hilly, so there can be lots of coasting, periodic hard ascents, and a fair amount of standing a stop-lights. Is this chronic cardio?


Falls Church, VA

My criteria for characterizing an activity as “chronic cardio” is more qualitative than quantitative. While some figures can be used as rough indicators (for the average Joe, obligatorily hitting the treadmill to “burn 500 calories” every day of the week usually constitutes chronic cardio), I’m more interested in how an individual personally responds to and regards a particular “cardio” activity than the distance and frequency traveled. For me, running anything longer than a few miles is “chronic,” because it stops being a pleasant, light run where I’m enjoying the sights, sounds, and smells and quickly becomes a grim battle against time and whoever else is running nearby. I get sucked into the competitive tunnel vision. With each stride, I grimace and descend deeper into the abyss. But that’s me.

You call your ride “healthy” and generally seem to have a good relationship with it. It’s not a race; it’s how you get from point A to point B. It’s not a straight shot, as you say. There are dips and climbs and coastings and chances to rest. You mention drudgery, but indicate that this bike ride is not that. This is a good thing. Now, if you’re dreading the bike ride every morning, if you’re sluggish to get up because your joints are aching, if your other workouts are suffering, or if you’re eating gallons of ice cream every night to fuel your activities… maybe the bike ride is a little excessive. But I don’t get that from you. Do you enjoy the ride? Do you feel stronger and more capable, rather than weaker and run down, as a result of riding? If you can answer yes to both, I’d say it isn’t chronic. Don’t sweat it.

Let me be clear, though. To any endurance junkies out there, no matter how much you love logging scores of miles each week, it’s still chronic cardio. I’m not saying you shouldn’t do it. Follow your passion. But just be aware that it isn’t the healthiest thing you could be doing, in my most humble opinion.

That’s it for today. In the comment section, go ahead with any followup questions and I’ll try to get to them. 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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64 thoughts on “Dear Mark: Carb Concessions, Nitric Oxide, and Chronic Cardio”

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  1. 45 definitely isn’t old! Good grief. Where does that come from? I feel better than I did at 25 and I’m looking over my shoulder at 45.

    1. I agree with you lol.
      45 is very young considering humans don’t reach maturity until age 30. So really he is only 15 years old, right? =P

      Old age doesn’t start until you eat SAD, feel the effects of eating SAD and walk slower than the 90 year old next to you with a walker.

    2. I can not wait when the day comes to where MOST people will think any age in their 40’s and 50′ and even 60’s is NOT old.

      I am 23 right now… maybe when I hit 40 this will be the case? I sure hope so.

    3. I’m 68. After a year of Primal, I feel like people should at 45, i.e., starting to slow down some and taking a bit longer to recover.

      1. Same here. I just hit 40 earlier this year and I feel like I’m back in my 20’s, and… minus all the digestive distress.

    4. I agree Allison, i will be truning 43 in a couple weeks and i feel great, most 20 year old will choke trying to keep up with me.

  2. I appreciate the answer on chronic cardio as I was thinking about it on my light jog this morning. I almost felt guilty deciding to jog for the first time in months, until I realized I finally had no expectations for myself. So I walked some, I jogged some, I enjoyed the sights. And it only lasted about 25 minutes. Not chronic in the least, for me. I think chronic cardio can sort of vary by person.

  3. You have good taste Mark. Game of Thrones is awesome. I’ve read the book and the two that followed, finishing the third last week. I’ve only seen the first and last episodes of HBOs Game of Thrones. Unfortunately I don’t subscribe to HBO but Dish periodically gives it to me for free. I guess I’ll have to wait for the DVD or for it to show up on iTunes to watch the entire series. It is a well adapted series.

  4. I buy bulk Arginine powder. I take 10 to 12 GRAMS at bedtime for a few weeks and then cycle off for a few weeks. I sleep better and wake up with a morning surprise every single morning (I am 42) and when I do heavy lifting my muscles feel swollen and fantastic! I sometimes even take an extra 5 Grams before a full body Friday workout (cleans and/or deads). So, yes! NO works for me!

    1. James, do you know of any studies (independent) tht have research the inflammatory effect of L-Arginine. I always though that L-arg was a pro inflammatory AA and therefore not a good idea.

  5. I’m a runner, and I run because I enjoy it. I am not fast – a 32 minute 5K and a 12-13 minute mile for longer distances. I’ve got a half marathon coming up in October – my first since going Primal – and I’ve done some really hard thinking about how to train without lapsing into chronic cardio.
    I’ve scaled my runs back to 3 days a week: one sprint day, one 3ish miler, and one long run that follows a traditional half marathon training schedule. Other days I lift heavy things, walk, hit a yoga class, do other interesting activities (rock climbing and road biking are two I’d like to do more) or rest.
    It seems to be working really well so far! I’m not burning out or feeling super sore like I have during past training, and I’m still able to tackle the longer distances.
    Again, I’ve thought really hard about the conflict between living Primal and being a distance runner, and I’ve decided that, as long as the runs are fun and I look forward to them, they count as “play,” and I give myself the blessing to move forward.
    I’d love to hear others’ thoughts about this!

    1. This is *exactly* the mindset I’m trying to follow. I ran 2 half marathons before finding Primal and did the 30-40 miles a week training thing.

      No more, going to use PBF as a “framework” — 1 sprint and 2 LHT every week and then “fill-in” with really slow runs to get what I think is enough mileage to prepare myself and call it all a mix “Move Slowly” and “Play”…

      I think you’re absolutely on the right track!

      1. Awesome, thanks! This schedule seems to work for me… I’ve done two halves before, too, and the events inspire me and get me excited to move, so I think it’s worth continuing! Best of luck to you!

    2. +1!! this is pretty much where I am at. I just did the Diva Half in Vail yesterday & I’m bouncin around the office with more energy than any other random Monday – just a little residual muscle soreness. I hydrated mainly with coconut water & had a few bites of a honey stinger bar along the way… and wolfed down 3 eggs in Kerrygold when I got home 🙂

      1. Cool! Running fuels I’ve tried: honey sticks (wash down with a swig of water), and dark chocolate espresso beans. Both seem to work really well, without ranging into the world of silly-processed foods. They both worked great, and make me feel great! My pre-race fuel right now is a fruit pouch (Peter Rabbit Organics).
        Do you like the stingers?

        1. I like the stingers – but are a bit sweet for me now that I don’t eat as much sweet as I used to. I got a bunch on sale through steep&cheap & keep them in the freezer. I put coconut water in my water bottle & that was that! I only had a few bites on the route during walk intervals. I ate the rest after the finish. Couldn’t believe the pile of bagels they were pushing at the finish – yick!

  6. Speaking of TV shows…

    Is anyone going to tune into Expedition Impossible this Thursday at 9 pm EST on ABC? It’s the final episode and guess who is in the final 4?

    Team Gypsies who are primal. No limits too!

    You better be watching! I will be watching with my primal chicago crew somewhere!

    Chronic cardio… I think this varies so greatly from person to person. For some, an hour jog is play while for others its work.

    If what you are doing is FUN, allows you to be in the moment and if you are not attached to the outcome then, well, go for it!!!! That’s play!

    Time for a quick 10 minute HIIT workout!

  7. I have been Martin’s fan foe many years!!! I am so happy they finally made the series! Books are of course million times better! Uhm, not much to say about the rest of the article, except that I am still looking for a perfect balance between lifting and HIIT.

  8. My boyfriend is Colombian. When we visit there we do have to turn down a lot of foods. They eat massive amounts of carbs, many of which are fried in vegetable oils. Their diet is based on starches which is problematic for me especially.

    I am a low carber, so I look like a stuck up American turning down foods that I only WISH I could tolerate, but my boyfriend and daughter aren’t so they eat yucca and plantain, plus fruit. All of those are just about as ubiquitous as beans and corn and they are natural foods which don’t contain anti nutrients and are available to primitive peoples. Stay away from things like yucca fritas though, because they are often breaded and fried in veg oil. They use cheap veg oils over there these days too.

    1. I hear ya, when i have travelled thru Central and South America, i have always eaten their food, sometimes it has been costly to my GI tract, but when i started to request food to be fried in coconut oil all those symptoms and reactions went away. For some reason the use of coconut oil, which often times is very available to them has not caught up as a healthy alternative to the veg oil they use regularly.

      1. I found some plantain chips in the bodega which were fried in palm oil. They didn’t look burnt and they didn’t mess up my guts. And they weren’t addictive to eat like most chips are. Funny, that.

  9. I love the chronic cardio debate!

    My definition of chronic cardio is hitting a treadmill, elliptical, or stationary bike and parking yourself there for an hour, doing the same speed the entire time and either watching tv or talking to a neighbor at the same time, all while thinking you are losing fat while doing it.

    If you’re riding your bike to work everyday because you you like it and want to and you know it’s healthy then good for you. If you are doing it and hate it, but are doing it to lose weight then try some metabolic resistance training and HIIT protocols instead. Time better spent.

    1. Yeah, Steve’s ride isn’t Chronic Cardio, it’s a commute! Good for you, Steve.

      1. A regular commute on a bike or on foot can actually be a wonderful way to destress.

    2. I commute by bike 30kms each way daily with a group of middle aged is a blast, social and sometimes competitive , we have a KOM challenge to keep the interest going…but in general chit chat and banter is the name of the game. I realise that may be considered chronic but the idea is to move often and have fun, doing the ride is the best part of the day, the rest is in front of a computer or in meetings…I also add that it is one less car on the road, I take up one less seat on the train, burn fat not oil and have never been fitter in my life…so it ticks a lot of boxes.

  10. Mark, don’t wait for the next season of the show! Read the books!

    There are 5 so far (the 5th one was just released right about at the end of the GoT TV season). They are the best fantasy books I have ever read, and probably in contention for the best books I have ever read in any genre, period. And that is not a short list of books; I probably average 2-3 hours of reading every day of my life since I was about 6 years old.

    By the way, the show is doing quite a good job of staying loyal to the story in the book for the most part so far, so it won’t be a situation where you’ll start getting annoyed at one or the other for deviating from how it was “supposed” to go (some people don’t seem to be bothered by that, but I always am).

    Everyone that I have talked to that has started reading those books has immediately gotten totally hooked on them.

      1. My only complaint about Name of the Wind is how slowly the completion of the whole series is coming!

        (And personally, I enjoyed Name of the Wind far better than the Game of Thrones series, but that’s me.)

  11. I’ve been reading Game of Thrones, about halfway through it now. Martin is a fantastic writer, really invests you in the story. Each chapter is a different character’s perspective; he rotates a few different perspectives throughout the book. I’m going to check out the show after I finish the first book.

    By the way, I enjoy reading these Dear Mark articles. Keep it up!

  12. I walk almost everywhere and generally bike about 6 miles on the weekend. Outdoors, but switch to stationary in the blasted Canadian winter. I’ve always been a fast walker, too, so I’ve wondered about this as well.

    I wouldn’t say my heartrate is soaring all the time, esp. when walking (unless I’m late! ;)) but I do work up a sweat biking. I don’t do it to log miles and do it every second week.

    Appreciate the post!

  13. I LOVE GAME OF THRONES. I started reading the books after the first season. Already on the 4th one. AMAZING!

    1. yeah, me too. GOT is fantastic. my partner and i got really hooked.

      “hodor hodor” has become a household phrase here 🙂

  14. I turned 48 this year. I’m still in great shape because I chose to be. I have a few more aches than I used to, and the way I exercise has changed, mostly due to the primal blueprint, but all in all I feel great. My new favorite saying is “Nothing tastes as good as skinny feel.”

  15. Do they serve a lot of salad dishes in latin america? Not bean or potato salads obviously, was thinking more like green lettuce, tomatoes, dandylions etc?

    1. I’ve lived in Peru for awhile in the past and would have to say that salad there is not really present except maybe in higher “class” areas of Lima. It all seems to depend on what part of the country you are in. In the jungle, it was mostly what people are talking about above (potatoes, yucca, meat, fish etc.)

  16. People go to the gym just to burn off 500 calories? Psh, I burn through that much by accident on a rest day.

  17. Nothing relevant food-wise to say, except I love the show (and the books! I finally got my parents to read them after years of proclaiming them too nerdy). And some of Martin’s food descriptions–Sisters’ Stew, clay-baked trout, etc.–make me very hungry to read.

  18. I am 47 years young and show up the young men I work with, in the gym. We can use the gym faclities at lunch times and I can count the number of indivduals that squat on three fingers…………and I am included in that figure. So far I have lost 14lbs and counting, following the PB with an increase in strength.
    If I am now classed as old bring on retirement as I feel and look better and better!

  19. Oh Game of Thrones!! Lol my husband loves the books…he started watching the HBO series during a free HBO preview weekend…after I saw a few minutes of it I said to him….oh great Sci-Fi and BOOBS…fine tv programing!! LOL

  20. I live in Panama and here the diet is rice-beans-beef (“arroz, poroto y carne” as the local saying goes). Also some corn, although not as much as in Mexico or the Mexican-influenced countries (most of Central America). Things like tortillas, tamales, etc.

    The beef is quite healthy, grass-feed (or mostly grass-feed), but rice is king. You get it served at almost every meal. The portions are sensible (substantially less than American ones). Veg oils are standard.

    The result? Young people tend to look very fit, but ALL 40-somethings are overweight, especially women. Heart attacks and strokes are the main killers. My grandfather’s generation ate mostly like that, but without the veg oil. Most of them lived beyond 90.

    And yes, if a campesino (peasant farmer) offers you food, eat it It is HUGELY rude to refuse. You can eat some and say you are full, that’s ok.

  21. Hi Mark! When are you going to give an update on The Unconquerable Dave???

    It is my favourite sucess story of all time!!

    1. YES! I love The Unconquerable Dave!!! He is a legend around my house! We need an update!
      Also Game of Thrones is wicked!

  22. I’m 52 and have been Primal for just about a year now. I’m not down yet to my “ideal” weight and I’m working on my fitness but I already fell better than I’ve ever felt. When I’m 53??? Sheeez, I’m going to feel Incredible, it’s almost scarey.

  23. “Winter is Coming” One of the best written lines there is… a foretelling for what is to come, for so many years the Thrones series was for book nerds 😉 I have read all of the books with the exception of the last one that was just released. I MAY watch the t.v. show based on all the positive reviews, but I guess I’d have to get HBO.

  24. Game of Thrones is phenomenal. I’ve been a fan of the books for years- the fifth just came out and I just finished it. They did a great job on the show!

  25. Game of Thrones is awesome, Read the first 5 books, then watched the show. Now i must wait forever for the 6th book and the 2nd season =(

  26. Hey Steve, that doesn’t sound like chronic cardio to me at all, in fact that sounds more like play!

  27. I’ve always wondered about this chronic cardio. I’ve always been perplexed by it since I heard Mark talking about it on this website of his. I mean, aren’t there long distance running tribes in Africa who run barefoot that are healthy as a horse? Not too mention rather well-built as opposed to thin and wirey?

  28. LOL. Bad wording on my part. I was referring to the CNN recommendation that NO is for “older men trying to gain lean muscle mass”. At 45, thanks to PB, I’m back playing soccer with the college players and holding my own. Never felt better!

  29. a sustained heart rate exceeding 80% of max gets old real quick. that’s cronic cardio, not fun. walking that’s fun.

  30. Waiting for “Game of Thrones” to come out on DVD… using the time to watch “Spartacus”… EXCELLENT! Finally we women get a fair shake with some fine full frontal males to watch! Oh yeah…. Crixus is definitely eating paleo style!!! Actually, come to think of it, he IS a perfect paleo dish… WOOOOOOOT!

  31. Beetroot juice helps boost nitric oxide, I didn’t know this. Even though I am still not convinced NO helps with building muscle, it definitely does have some health benefits that could warrant me juicing up some beets.

    Thanks Mark

    1. Furthermore, when we breathe through our nose, the air passing through the nasal airway and contacting the turbinates — shelf-like bony structures — is slowed down. This allows the proper mixing of the air with an amazing gas produced in the nasal sinuses called nitric oxide (NO).

      Nitric oxide is secreted into the nasal passages and is inhaled through the nose. It is a potent vasodilator (dilatation of the blood vessels), and in the lungs it enhances the uptake of oxygen. NO is also produced in the walls of blood vessels and is critical to all organs in the body.

  32. When I’m home, I’m a 110 mile per week bicycle commuter. Love every minute of it, even in the dead of winter. Pushing a bike through 4″ of fresh snow is a great workout. So in my mind it’s not chronic cardio.

    But I’m just 18 months removed from my last 50K trail run. That was the end of 20+ years of marathons, ultramarathons, Ironman’s, running 40 miles for my 40th, etc.

    This year, the longest run has been 7 miles, but that was a fun day of speed play.

    At 43, it sure is fun to be standing at the finish line of our 1.5-mile PT test, having recovered, waiting for the 20-something’s to cross the line.

    So Thank YOU for the refocus, Mark!

    BTW, what’s the recommended dosage for Arginine? Sitting here in Afghanistan, where the Primal food selection is spotty, I have to supplement, and an amino supplement has served me well over the years. My current aminos provide 106mg (3x daily).

  33. Thanks for the clarification on the chronic cardio thing. I built a tread desk and have had some say that it equates to chronic cardio. I get between 50 and 100 miles a month. I see it as I could be doing that, or sitting on my ass in front of a screen. I prefer walking.

  34. YESSS, GAME OF THRONES!! I’m currently reading it, actually. I’ll catch up on the show later. From what I’ve seen, it’s not a disappointing interpretation of the books.

    I always save cardio for after my lifting sessions. I’m supposed to do steady-state cardio for 20 minutes so I don’t hurt my recovery, but I get WAY too bored after 10 and start doing intervals without thinking about it. I can’t believe I used to run 30 minutes at the same speed. So boring!

  35. I just went primal as a way to train and get in better shape for a sprint tri (and life) and it actually seems to PBF plan perfectly for me. The tri is a 1/2 mile swim, a 12 mile bike, and a 5k. Leading up to the that in a month i planned a 2 day a week bike (I bike to the pool 8 mi) and swim that are at the correct hear rate. One day of sprints and the 2 lift heavy days. Loving it so far!

  36. This thing are essential for our life. This is a supper article where we find some more details about this thing. Especially thanks to share it with us.

  37. A note on beets: every morning and night I have some beet kvass. Since I started drinking this I have a lot more energy… almost did not know about it…! And it’s good for your gut, liver, blood….
    Nourishing Traditions (Sally Fallon)has the recipe. I make my kvass a lot less salty and it works perfect.