Dear Mark: Vitamin K2, Washing Eggs, Tapioca Flour, Short Term Grain Feeding, and a Raw-Fed Pack

I both love and hate the time change that just happened. Those first few days are magical. You wake up on Sunday at around 5:30, and you’re raring to go. Full of energy with a whole day ahead of you, plus an hour. It’s like time slows down and you’re ahead of schedule on everything. It’s always an hour before you thought it was, no matter what time it is. But then you get used to the time change, and you notice it’s getting dark out at like four in the afternoon. The afternoon ceases to feel like the afternoon. You get sleepy earlier, which is a good thing in some ways, but I also like to get in something outdoorsy later in the day. Maybe a hike, maybe some paddling. I can’t do that anymore.

All that said, the time may have changed, but Mondays stay the same: Dear Mark question and answer sessions. Today, I discuss the fate of vitamin K2 during dairy pasteurization, explain why I don’t wash my eggs, and give my thoughts on tapioca flour. Then, I field a very sad story from a reader in Argentina and try my best to assuage him. Finally, I discuss the potential costs of feeding a pack of large dogs the raw diet.

Does pasteurizing dairy destroy its Vitamin K2?


While there’s no smoking gun of which I’m aware, it appears as if vitamin K2 is retained during pasteurization. See Chris Masterjohn’s definitive article on vitamin K2 (or “Activator X,” as Weston Price knew it) where he notes that everything he’s seen suggests that it is heat-stable. Price himself found that “Activator X” survived pasteurization. And according to Real Milk (a pro-raw, anti-pasteurization dairy site), this article sees “no evidence” that pasteurization affects “Activator X”  status.

If anyone has evidence to the contrary, I’d like to see it, though.

Dear Mark,

Is it safe to eat farm-fresh eggs without washing them? If they should be washed, what is the best method?

Steve L

If you trust the conditions of the farm, I don’t see a reason to wash the eggs. I don’t even always refrigerate the pastured eggs I get, let alone wash them. The farmers don’t wash them either.

Premature washing of an egg removes the “bloom,” the thin protective layer that prevents bacteria from entering the egg (which is actually slightly porous, believe it or not). Excessive handling can also remove or degrade the bloom, but most farm fresh eggs – in my experience – don’t undergo a lot of handling. Besides, if eggs didn’t come equipped with natural, protective shielding and instead required the loving hand of a farmer, some running water, and a dollop of bleach to survive until hatching, chickens never would have made it to 2011.

Washed eggs actually go bad quicker than unwashed eggs. Don’t wash your eggs.

I was wondering about tapioca flour. I have found it locally. It is gluten free. I was wondering if it could be used like coconut flour. Thanks.


Tapioca flour is one of the “safe starches.” That is, it’s a toxin-free, antinutrient-less, dense source of carbohydrate. I wouldn’t exactly compare it to coconut flour, which is extremely high in fiber, low in digestible carbs, and really soaks up the liquid in a recipe. Tapioca flour can be treated more like potato or rice starch. It’s a classic carby flour, albeit one without gluten and other noted toxins.

For someone with good glucose control, tapioca is a decent source of carbs. If you’re looking to add carbohydrates, or your activity level warrants it, go ahead and try it out. Since tapioca comes from cassava, which is perhaps the most popular source of starch across the entire world, it’s not like it’s a dietary unknown. To venture into tapioca territory is to travel a well-beaten path. Just realize that anytime you turn something into flour, you massively increase the speed at which it breaks down into usable energy. High energy burners in need of a quick hit may find that to be a plus, while more sedentary individuals might react poorly to a quick infusion of glucose (especially if it’s not going to be utilized right away or sequestered into already swollen muscle glycogen stores). Your call based on your context.

Please help me get this straight: I asked my butcher and he told me the meat he sells comes from cows that are pastured their whole life and then are sent to feeding lots for the last 15 or 20 days before being butchered; he referred to this as “supplemented cows”. To me is quite clear this is “grain-finished” meat.

My questions are: Does this beef still counts as “grass-fed” or should I take it as plain and simple “grain-fed”? Do those last 20 days of eating corn nullify the previous 3 or 4 years of grazing? From a nutritional point of view, does this kind of grain-finishing cause the same result as ordinary grain-feeding (I mean, keeping the cow in a feed-lot for longer periods of time)?

I would REALLY appreciate some answers and/or any piece of information you could point me to in order to clarify this situation.

As always, thanks a lot!


Juan (writing from Argentina, once known as the-land-of-grazing-cows! Well done, civilization!)

Juan, I feel your pain.

But don’t despair. I wasn’t able to find any data on the effects of 10-20 days of grain feeding on otherwise grass-fed cattle, but I did find a study that compared the nutritional content of beef raised three ways: grass-fed for life, grass-fed and grain-finished for the last 80 days, and grass-fed and grain-finished for the last 150-200 days. As you might expect, grass-fed for life contained the most omega-3 fatty acids and CLA, while feeding grain reduced omega-3 and CLA. No surprise there. Grain-finishing decreased omega-3 and CLA content. Also no surprise.

However, it wasn’t as if that first mouthful of corn and soy immediately removed omega-3, lowered CLA, and irrecoverably altered the nutrient density for the worse. The benefits of grass-feeding weren’t totally undone, and grain-feeding didn’t work like an on/off switch. Rather, it’s a spectrum. Cattle that were grain-fed for the last 80 days of their lives had more omega-3 and CLA than cattle that were grain-fed for 150-200 days. In other words, the longer you grain feed, the more you impact the nutritional content of the animal’s meat. That would leave me to believe that 10-20 days of grain feeding is probably enough time to negatively impact the nutritional makeup of the meat (and especially the omega-3/CLA content), but not enough time to undo all the good of grass feeding.

It’s also worth noting that one of the biggest problems with feeding cattle grain for life is that it usually requires the use of antibiotics. If you feed them a diet they aren’t genetically adapted to for long enough their health will suffer and drug intervention will become a necessity. Grass-finished cattle (the shorter the period the better) are less likely to need antibiotics.

So, 10-20 days appears to be on the low end of the spectrum. I’d say eat away.

And I was planning on visiting Argentina sometime, too. Dang. (Kidding; I still want to go!)


I accidentally ran across your article about the raw diet for dogs. I am interested in it. However, with feeding 9 large dogs (wt 70lbs to 120lbs) will it be cheaper than what my pet food bill is now? I currently spend 450 a month on the dog food, with one of my dogs having a special diet because she is allergic to everything, and I do mean everything, except veggies (green beans, carrots, sweet potatoes) and fish. Also, do you know of any websites where I can buy organ meat? Thank you in advance.


I doubt it, but it really depends on your sources.

I’ll give an example. One of my Worker Bees has a 70 pound dog who eats all raw. He’s lucky, because he has access to a raw-feeding co-op which gets incredible deals from local small farms. All the meat is human-grade, pastured, grass-fed, and often organic, and it’s very affordable. His dog gets about one and a half pounds of food a day, mostly meat, bones, and various innards (liver, tripe, spleen, trachea, all sorts of cool stuff), supplemented with yogurt, fish, berries, shellfish, and sometimes vegetables. For convenience, he also buys preformed raw meat chubs of ground meat, bone, organ, and vegetable for $2/lb. He feeds his dog on $3 a day. And that’s grass-fed, high quality stuff. Very doable with one dog. With nine, though? That would get really expensive, really fast. Say all nine dogs are 70 pounds (which yours aren’t) eating $3 worth of food a day. At 28 days a month (allowing for a few days of intermittent fasting, which dogs are naturals at), that’s $756.

However, said Worker Bee lives in the SF Bay Area, where prices are generally higher than in other areas of the country. Things might be, and probably are different in your neck of the woods.

Here’s what I’d recommend: find a butcher or meat counter and get to know the people who work it. Tell them you need a steady supply of muscle meat, organs, and bones for your pets (many butchers will have experience preparing pet food for customers) and tell them your budget. Figure about a half pound of food for every 25 pounds of dog and go from there. Don’t worry too much about grass-fed this or pastured that; even conventional meat is better than kibble (especially considering the kibble makers use the cheapest “meat” possible in their products). There are online sites that sell organs and even pre-mixed raw dog food, but they run around $2 a pound at the least. At those prices, your monthly bills will run over $450, no question. I think you’ll end up paying more than $450 a month regardless, but I suspect you’ll save a ton on vet bills.

Join this Yahoo raw feeders’ group. I’ve heard nothing but good things about it, and it’s very active with a lot of helpful members wiling to give advice. There’s a good chance you find someone near you who can give more specific advice. Good luck!

That’s it for this week, folks. Keep sending the questions along, and chime in with any new ones related to today’s topics in the comment section. Thanks!

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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