Dear Mark: Kosher, Weak Nails, Tea Seed Oil, and Greasing the Groove

Another Monday means another set of questions from my dear readers. I covered Ramadan already, so this week, I’m covering whether eating kosher makes eating Primal harder or easier, including what to watch out for and what to replace it with. I give my thoughts on nail-strengthening dietary strategies (and give bone broth a much-deserved plug) and explore whether tea seed oil is actually worth using (hint: it’s not exactly like those industrially-processed seed oils we hate around here). Finally, a reader unwittingly stumbles upon an extremely effective workout strategy, simply by trying to be more “Grok-like.”

Let’s go.

Dear Mark,

Now that you have addressed how to handle Ramadan, I was hoping you would give the limitations of keeping kosher a stab! My dietary restrictions influence my food choices (ie, no shellfish, no butter/dairy when eating meat/chicken, and obviously no pork/bacon), and I am wondering how to still meet the Primal [Blueprint] diet targets. Any advice would be greatly appreciated!


You’re in luck. The only tenets that would impact the Primal nutritional “targets” might be the shellfish restriction and the no-meat-with-dairy law. As I mentioned in the post on shellfish, oysters are the richest sources of dietary zinc, an important mineral lacking in many modern diets. Getting zinc elsewhere is easily accomplished – just eat lean beef shoulder (100 grams gets you 10 mg), lamb, or bison. And since dairy technically resides in a Primal gray area (despite the community’s general acceptance and adulation of grass-fed butter), you’re not missing much. Olive oil, coconut oil, beef tallow (as long as you avoid tallow rendered from the fat that lines the cow’s organs; that’s called chelev and it’s definitely not kosher), and palm oil are all fine cooking fats that don’t upset the kosher dietary laws.

Hi, I’m enjoying the Primal [Blueprint] diet, but I have gotten weaker nails. I eat lots of eggs, meat, vegetables, fruit, and nuts. What should I then eat more of?

Thank you,


Eating lots of meat should take care of your B-vitamins, a lack of which could cause brittle nails, so I don’t think it’s that. You say you eat a lot of nuts. Are you also eating fatty fish or taking fish oil? I’d be wary of your omega-6:omega-3 ratio, which, if weighted too heavily toward omega-6, will be inflammatory.

After researching for the “Cooking with Bones” post a couple years ago I got serious about bone broth. Whereas before I would only make broth whenever I had leftover bones, after writing the post, I started buying bones specifically for making broth. I made sure to always have some sort of stock – chicken, beef, lamb – on hand in the freezer or fridge and ready to go. I might toss a cube of frozen broth into sauteed veggies, when braising meat, or even just by itself in a cup. I never set a schedule or kept track or anything, but I estimate that I had some form of broth three to four days a week. What does this have to do with nails, you might be wondering? All that broth had a definite effect on my nails: they got stronger, thicker, and harder. Now, this is just an anecdote and I don’t have any data to back me up, but the broth could have been partly responsible. I’ve heard similar testimonials from others around the web.

Real bone broth, as you probably know, contains gelatin and an as-yet-unconfirmed mix of bioavailable nutrients (calcium, magnesium, and who knows what else). Gelatin is the protein that makes your broth turn to jello in the fridge. In fact, the sign of a good broth is the jello-like consistency when cold. It should really wobble. Minerals are used by the body to manufacture bone and other structures (including fingernails), neurotransmitters, and various hormones. If your diet is lacking in minerals, broth is a good addition. Try to always have bone broth on hand (freeze in ice cube trays for easy storage and access) and try to eat some every single day. Barring that, just use powdered unflavored gelatin.

I would also make sure you’re getting plenty of vitamin D and vitamin K2, both of which are involved with calcium deposition. Get some sun (or take a supplement) and eat some liver and grass-fed butter (or, again, take a K2 supplement). Vitamin C is also important for nail health, so add some bell peppers, broccoli or strawberries to your diet if you haven’t already.

Hi Mark – Wondering your thoughts on camellia or tea seed oil. Is it Paleo, how does it compare to the other oils you talk about on MDA?



Tea seed oil looks like a solid cooking oil. It’s high in vitamin E (increases resistance to oxidation and heat damage), extremely high in monounsaturated fat (80%), and it has roughly equal amounts of saturated fat and polyunsaturated fat (10% and 10%). There’s not a ton of literature on it – mostly articles written by companies selling the stuff – but I did find an interesting abstract of a study in which tea seed oil offered hepatoprotection to rats with toxin-induced liver damage. Most seed oils are high in omega-6 fats and actually increase the liver’s susceptibility to damage, so if tea seed oil pans out, it’d be a nice change of pace. Hunan, a province in southern China, apparently uses tea seed oil as its primary cooking oil.

I’d be really interested to see how disease rates in Hunan compare to disease rates in other provinces that use soybean or some other high-PUFA oil for cooking.

Dear Mark,

I’ve been doing the progressive LHT workouts twice a week for around two months and have made some progress. Recently I’ve been thinking: would it be more accurate (at least Grok-like) to do bursts of the essential movements throughout the day on most days of the week (assuming allowance for a rest day)?

Example: I just read the WOW about going for the hour walk and fitting in the essential movements during that walk – it resonated with me more than working out for 30 minutes twice a week.

Bottom Line: Would incorporating the essential movements into everyday life on most days of the week (in bursts intense enough to FEEL the movements being done) be a feasible replacement for the regimented 2X/ week LHT workouts?

BTW – LOVE sprinting! SO much!!! I do need to play more though 🙂

May Grok be with you ;),

Emily Mekeel
-Future Dietitian and PB Warrior!

Your intuitive exercise idea isn’t just more Grok-like, it’s also (and more importantly) a legitimate way to strength train. Have you heard of Pavel Tsatsouline? He has a workout methodology called “Greasing the Groove” that’s extremely similar to what you describe. When you grease the groove, you hit a movement multiple times per day, as often as you can without getting fatigued. Pretty much whenever you get a chance to do the movement, you do it. So if you’re trying to grease the pullup, you might do five or six pullups every time you see the pull up bar, ten times a day perhaps (or more!). So by the end of the day you’ve done fifty to sixty pullups without having to grind any of the reps out. Each rep is crisp and clean, and you never go to failure. You never really struggle but you’re getting a lot of volume in each day. Each rep feels easy, you feel fresh, and yet you’re constantly getting stronger.

I think it sounds like a great idea, especially since it’s resonating with you more than the traditional setups. I always say that the most important aspect of any workout regimen is that you enjoy doing it, and it sounds like you’re really digging this. I say go for it (and don’t forget to play)!

Well, that’s it for this week. I have some questions in the queue, but I’m always taking more. Send them along and 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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66 thoughts on “Dear Mark: Kosher, Weak Nails, Tea Seed Oil, and Greasing the Groove”

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  1. Hey thanks for answering the question regarding kosher dietary restrictions. While I am not kosher, my fiancee is and therefore I am too…your answer helps but would love to see an expanded answer. thanks for all your good work!!

    1. It has always bugged me so much that people involve food and religion with each other. It’s as dumb if not dumber than involving religion and politics/governance.

      I mean, god doesn’t really want to restrict you does He/She? What kind of an evil god is that? Is god that petty?

      Anyways, eat your food, don’t restrict yourself. Nuf said.

      (Don’t start a religion feud over this, please.)

      1. It’s not a religious feud, simply a person (or many persons) beliefs. If you believe in the old testament, there are restrictions that have been laid out. Some people think that pork was a dirty meat (trichinosis anyone?) It is pretty well accepted that digestion of meat is hindered or affected by the simultaneous ingestion of dairy. Some people feel that the laws (or kashrut)is because you need three things to live; air, water, and food. You have to breathe, you have to drink, so therefore food is the only way that one can show respect for God and make a conscience decision (showing you think as an evolved, free-thinking human rather than an reactive, instinctual animal) to choose one item over another because it’s what God asked you to do.
        There are many different opinions as to ‘why’ the restrictions are there, but the bottom line is, ‘they are there’. You don’t have to follow/believe them, but there is no reason to label a persons religious beliefs as ‘dumb’. If anything, a person choosing to be Kosher based on religion is already a step ahead of most people as they are very mindful as to what they are putting in their bodies and why.
        Don’t be closed minded and judgemental, and most importantly, don’t judge that which you do not know. Nuf said….

        1. Thank you! Making a conscious decision about what to eat, etc. – isnt that what this site is about? There are plenty of CW-followers who might think we a “dumb” for “giving Up” so many foods….but we know better and feel better for it.

        2. “It is pretty well accepted that digestion of meat is hindered or affected by the simultaneous ingestion of dairy.”

          Only if you have issues with dairy. Our stomachs are pretty good at handling various foods. It’s simply not true that combining types of foods means they don’t get well digested. Just because a lot of people believe it, and have for a long time, does not make it a fact. CW, anyone?

        3. with the non-judgemental approach to one’s conscious choices for eating or whatever.

  2. Love the idea of working the strength moves into your day. I will stop and do squats when I am walking sometimes. Check out Cranky fitness today, she has a post about this exact workout. Seems like a great idea.

  3. I totally agree with the idea of working in the exercises throughout your day! I think it sounds a lot closer to how our primal ancestors would have done it.

    Also, thanks for the nail tip. Mine are generally strong but go weak when I start eating grains. Interesting.

  4. Thanks for answering Emily’s question, Mark! It also answered the one I sent you.

  5. Eating Liver, taking High Vitamin Butter Oil, drinking bone broth and 2 cups of RAW goats milk has made a HUGE difference in my nails, hair and skin.

    For the first time in my life my nails are rock hard (so are my teeth), my skin is tougher and less flabby and my hair is growing faster than ever.

    1. Yep. Strong nails and hair are all about nutrients and those foods are packed with them. If your nails are brittle and weak but you think your diet is perfect, maybe you’re not absorbing your nutrients.

      1. Hi Peggy,
        I just went to your site and read about the carnivorous diet. This sounds like me, exactly! I do best on a high fat, moderate protein diet but I’m always worried about the alkaline/acid balance, so I base my meals around vegetables even though I kinda hate them.
        When I make stew I find myself picking the meat and fat out, when I make salads with eggs and bacon I find myself picking the bacon and eggs out leaving all the green crap behind. I have to make a concious effort to ingest green stuff.
        Are you at all worried about the alkaline balance? What do you think about it? I’d be very interested in what your opinion is on that.


        1. Years ago I had got myself pretty scared about acid/alkaline balance. I bought those test strips and paid close attention to the supposed symptoms of imbalance. I had all kinds of symptoms back then and I ate tons of veggies. It simply didn’t make any sense to me that I should be out of balance. In fact, I ended up doing everything I could to try and bring my body back into balance. Nothing ever worked. I always seemed to be highly acidic. When I finally read The Fiber Menace, it all started to fall into place. All those veggies which I wasn’t digesting was CREATING the acidity. I have no symptoms of being acidic anymore even though all I eat is meat. I do eat a lot of special foods, though, which I imagine makes a difference. I don’t eat processed meats either very often. Those DO make me acidic.

        2. For some reason I can’t reply directly to you.
          Thanks for the reply. From what I understand now is that cooking itself creates acidicy and anything that is indigestible, like insoluble fiber.
          Man is too smart for his own good, taming fires and crafting pottery for cooking made him decline in bone density and overall health.
          I am, too, terribly bloated (and often constipated) after eating ANY plant matter, vegetables more so than fruit.
          I don’t think humans ate ANY plant matter before the event of pots, even with just a fire humans only roasted tubers and chestnuts and had no way to prevent plant matter like Kale from wilting near the fire. This is probably also instinct from kids to hate veggies.
          I’m going to start cutting down on fibrous plant matter and instead of cabbage/pork stew I’ll be making an organ meat casserole in the oven.
          Maybe I can allow myself to have some organic tubers again which I love so much with butter and sea salt, and which I haven’t had in 1.5 years because I was afraid of excess insulin.
          A tuber actually makes more sense to me than kale, chard, broccoli, cauliflour, asparagus or mustard greens.

          Thanks again 🙂

  6. The finger nail idea with eating more bone broth is very interesting. I usually do have week nails too, not while pregnant, but will keep this in mind! I actually just made chicken soup from the carcass of my roasted chicken from last night!! Yum Yum!

  7. My son has deep grooves in his nails that I’m convinced are diet related. He eats tons and tons of nuts. I wonder if his omega 3 and 6s are totally out of whack–it seems likely, because he’s not taking fish oil or any other supplement high in 3s.

    I’m so thankful another reader asked this question!

    1. This seems plausible. I’d suspect though that it’s less about the excessive n6 and more about other dietary deficiencies directly or indirectly caused by the nut consumption. Nuts are high in phytic acid which interferes with nutrient absorption and eating “tons and tons” of them mean it’s displacing other healthful foods in his diet.

      The nail ridges will go with better nutritional balance (bone broth), supplanting meat/sat fat for the nuts etc…

  8. I have been working on my toenails for the past year. They were an absolute mess with fungus and they had all kinds of wobbles and grooves. I have been using tea tree oil for the fungus and the grooves have been going away. I can’t confirm whether or not my diet has anything to do with it but I can stand to look at my feet now.

  9. Love Pavel – he is pretty “primal” without even intending to be. He is the reason I got into kettlebell exercising too.

    I try to use the “greasing the groove” philosophy in some of my bootcamp workouts. Instead of killing your bootcampers, like many instructors seem to do, you allow them to work longer, and increase their work volume.

    It’s a good thing.

  10. Pavel is a god in the strength training world. When I was in high school I put up a pull up bar in my room and did a couple when I went in and out. I went from being able to do 1 pull up to being able to do 11 pull ups in 10 days!

  11. Unfortunately, kosher meat tends to be expensive, tough and not very flavorful (in part because it’s a specialty product and there are a lot of rules involved in its production). Luckily, kosher poultry is often better and easier to find.

    But I think it would be hard for a lot of people who keep kosher to follow a strictly paleo plan, especially if they’re avoiding processed deli meats.

    1. It isn’t necessarily that difficult to keep kosher and paleo/primal/caveman/clean. There are quite a few options out there. KOL Kosher foods is available for order on-line, there is Wise that does mostly poultry, and there is Teva meats (still checking to see if their animals are free range or not, so far, no answer). I don’t eat dairy so the separation isn’t an issue. Hang in there, you’re not alone, and you can definitely do this.

    2. Kosher meat is expensive – but tough and unflavorful?? I cant say as I have no basis to compare…however, most people who keep kosher choose to live where they can get kosher food easily. As mentioned below, organic and free-range are available on-line mail order. (Which is even more expensive, but for a small family may be do-able).
      Going primal is NOT hindered by being kosher….I’ve been doing it for months. If I could, I’d buy grass-fed meat, but I am doing fine without it.

  12. “Greasing the Grove” is great. It helps break up the boredom when just hanging around doing busy work. I also make it a point to get more play time in with the kids. I get as much out of the monkey bars as they do.

    Now, if you’ll excuse me, I need to go look for some bones and make some broth.

  13. Nothing could be finer than bone-broth soup! My wife and I made a chicken soup a few weeks back that included 2Q of bone broth. It was phenomenally good!

  14. I’ve seen so many improvements, but my nails are still weak. I’m going to make bone broth more regularly and see if it makes the difference.

    Anyone else have success strengthening their nails?

    1. since I’ve gone (mostly) primal my nails and hair grows faster and stronger. I haven’t got around to making bone broth yet. I’m getting plenty of protein and fat and I’ve completely eliminated grain. I do eat a small serving of berries everyday and I take a vitamin c supplement.

    2. My nails became much stronger and grow faster since adding bone broths.

    3. Absolutely. Mine were great most of my life, then during a period of seriously crappy nutrition went all to hell, peeling in layers, splitting down the middle, ridges, breaking off with any length.

      Now they’re amazing. Stronger than they’ve ever been, growing so fast I have to file daily or every other day.

      I did add about 2 cups (before concentrating) of bone brother per day from grassfed ruminant animals and went hardcore on my n3:n6 ratio.

    4. I started taking magnesium malate for general health and in a few months my nails grew out strong and hard. I could hardly believe it! Don’t take the mag. with calcium, it will be wasted.

  15. I like this greasing the groove Idea , definitely going to try it for the next month.

    Dim Sum chicken feet, beef tendon, tripe and beef stomach for serious nails , strangely the I F ing seems to speed my hair and nail growth but I have no proof just anecdote.

    I have a messed up thumb nail from a car door slam.

  16. Silica is important for strong nails and strong bones. Diatomaceous earth (food-grade … not the kind for pools/yard) is a great source, but may be too weird for some. Beer is another good source.

  17. I love the greasing the groove idea. I was actually planning on going ahead with doing that this entire month. I was thinking doing an intense 10-30 minute strength routine of bodyweight exercises 1-2 times per week instead of 3-4. I think this post made me settle on just once.

    Then I was going to do bodyweight stuff randomly throughout the day. Why? I absolutely love doing push-ups pull-ups, squats, bunny hops, toad leaps, jumps, burpees, lunges, etc. LOVE

    Yesterday I played one round of mini golf. After each hole (starting on hole 11ish) I did 10 push-ups and 10 squats… I loved it!

    Thanks for answering this question Mark even though it was not mine!

  18. Since the subject of nails came up, I have a friend with white spots on her nails.

    Anyone had any luck getting rid of them? Or, have any idea what causes them?

    1. I have heard that white spots on nails is a sign of a Zinc deficiency.

      1. Everyone on the internet says white spots on the fingernails signify a zinc deficiency, but when I traced it down, nutrient by nutrient, for me it was a Vitamin C deficiency.

    2. I used to get a lot of those white spots on my nails – since I’ve stopped eating wheat I haven’t had any new spots come out. I haven’t added any supplements to my diet, just reduced wheat!

      1. Whoa, I just noticed this too because I checked after reading your comment. I hadn’t thought of that in a while. I used to have prominent spots on almost all my nails. I have some spots now but they’re a lot smaller and not as noticeable. This is after 6 months of mostly being really dedicated to eating primal. Primal FTW!

    3. I had white spots on my nails practically my whole life and always I hated it. In my case I’m pretty sure the cause is fats. They disappeared after going primal and I initially chalked it up to ditching gluten. However a few months in I temporarily went dairy free and the white spots promptly returned – I can only assume the reason was that the dairy free diet inevitably led to increased omega 6 intake (cooking with lard/olive oil instead of butter, increased consumption of nuts) as this was the only major change I could see from the lacto-paleo diet. Soon as I returned to lacto-paleo (about 3 months) and minimised nuts, no new white spots.

      Sure, white spots on the nails are not that big a deal in the scheme of things, but they are annoying – and I can’t help but suspect they are indicative of something awry in the body. It’s great not to have them any more.

  19. My nails have become incredibly strong after ditching the grains, sugars & dairy. They used to be so weak, even slightly bumping against a desk would cause a break right into the cuticle bed (ouch!). Now, my nails grow so fast, I have to trim them regularly, but no breakages… I actually get comments on how nice my nails look!

  20. My husband and I both noticed our nails were strong and growing like crazy after 10 days in Hawaii last month. I know from recent blood work that my Vitamin D is low ( I went from 19 to 35,so I’m getting better) and the husband’s has to be as he is outside less than I am. I would definitely check Vitamin D levels.

  21. I would warn against “greasing the groove” style workouts using only 1 movement. Instead opt to do oposite movements to balance your body out. I have a lot of clients who have tried to do the “100 pushup club.” Same concept, do pushups whenever you can untill you reach 100. Problem is then they come in with and overdeveloped chest, and chronic rotator cuff pain. Their chest tightens up and pulls their shoulders forward, straining the rotator cuff. This problem can be fixed by simply doing the same amount of rows (or whatever antagonist exercise you need) as the pushups.

    1. I agree that you should be careful “greasing the groove” as Jaybird says…my boyfriend did pull-ups like this for a month or so and developed carpal tunnel like symptoms in his arms. It went away went he stopped doing this. Probably just needed to balance out the muscles being exercised.

      That said, I’d like to try it (not as many reps as my boyfriend did) to see if I can surpass my measley 4 pull-up count. Being able to do 10 in a row would be awesome!

  22. a little of this, a little of that…I like it. I’m definitely gonna be “Greasing the Groove” this month. Thanks for the change up.

  23. Anyone have any good tips for using stock regularly? I have some great stuff in the freezer, but aside from stews I’m kind of at a loss as to what to use it for

    1. One of the staples in our fridge is a container(s) of homemade chicken and/or beef broth. We eat lots of steamed veggies, and I add a big spoonful of stock to the pan when cooking the veggies. It boils/evaporates down – along with the water in the veggies – leaving a nice non-oily flavor. (I also add some coconut oil or other fat.) The stock seems to always work no matter what type of veggie I’m cooking, but I’ve noticed that sometimes chicken works better than beef and vice-versa – depending on the veggie and your taste buds.

      Bottom line – if nothing else, just drink the stuff up as a broth before dinner or during dinner instead of tea or coffee (coffee as my DH is so used to doing – ugh! – he says it’s a Mid-Western ‘thing’ – more Ugh!”)

      Another one of my favorites is to use the stock to make various types of creamy soup using veggies (when in season) such as zucchini, broccoli or cauliflower and freezing the soup for use during the winter. Cook all the veggies in the stock and then puree and freeze in containers for winter use.

      The obvious is soup or stew or those types of meals – but just think about where you can use the broth in place of all the liquids you use/drink during the day.

    2. I drink two cups every day. My kids love it. The dogs love it. I also make a lot of soup – broccoli fennel, cauliflower dill and more…

  24. GTG is by far one of the best methodologies when learning a new movement pattern to build the memory towards it. Works very well for body weight exercises, especially pull-ups and pistols.

  25. Most of my workouts occur while out walking the dog. Sprints, stopping to do calisthenics or climb something interesting, all fit in really well. Breaking up the workouts, at least not being OCD about making them a particular way, but just about doing them, has been an boon to me. At 48 with a six year old still at home, I do what I can whenever I can. Any more structure than that just kills the workout altogether.

  26. For a second there, with a phrase like “Greasing the Goose” and a picture like that, my primal mind went straight to the gutter. Lol. Great post Mark.

  27. Thank you so much for answering my question Mark! I just got the chance to read this and I’m about jumping out of my chair with excitement!

  28. Jonas – This is just a precaution, but you might want to get your iodine levels tested. I had an iodine deficiency recently, and supplementing with iodine actually hardened my nails and made my hair shiny and smooth again! It also cured a whole host of other problems I was having, but I won’t go into detail here.

  29. Greasing the Groove: wow that is a revelation for me. We have a nice fitness room at work and the last two days I’ve popped in after each bathroom break and given it a go. It also serves to warm me up in our far-too-cold building! Thanks1 -Alane

  30. Hey Mark – thanks for answering my tea seed oil question! I had the same problem – couldn’t find much literature on it. Sounds like it’s not so bad, but I don’t see a compelling reason to run out and buy some either.

  31. I always say that the most important aspect of any workout regimen is that you enjoy doing it,

  32. A good portion of my exercise is “greasing the groove,” I just didn’t put a name on it. As a stay at home mom I almost never can find time (or child care) to go to the gym, so instead I come up with a sort of game each day…15 squats/push-ups/whatever each time I open the fridge/go to the bathroom/climb the stairs/whatever. Different exercise and cue each day. Another favorite is adding an extra stair climb – up, down, up or down, up, down every time. It’s been too hot to go outside, so I’ve had to get creative!

  33. I haven’t heard of any research on the tea seed oil, but it turns out there are many seed oils with high omega 3 content relative to omega 6. An example is chia seed oil.