Last week, I wrote about how the available evidence indicates that full-fat dairy is a very healthy, nutritious source of food for people who tolerate it. The comment section exploded with questions, so I figured I’d use this week’s “Dear Mark” to answer most of them. First up is a question about dairy’s oft-reported positive effect on weight gain. Next, I briefly go over the A1/A2 milk issue. Is it something you actually have to worry about? (Maybe.) After that, I discuss whether dairy has to be raw to be worth eating (or drinking), and I give my rationale for choosing the dairy that I do. Then I give my take on why the osteoporosis rates in the United States are high despite our high dairy consumption, followed by whether using inflammatory forms of dairy to heighten the post-workout spike in inflammatory markers makes sense. And finally, does a gluten intolerance make dairy more problematic?

Let’s go:

I do wonder, though, why dairy is often implicated in weight gain (or weight loss stalls). Is it simply a matter of a calorically dense food that is easy to overeat? Or is there something else going on?

There seems to be conflicting evidence, doesn’t there? On the one hand, the bulk of available studies suggest an inverse association between dairy intake and weight gain – people who eat the most dairy, whether it’s cheese, milk, butter, or yogurt, seem to lose the most or gain the least weight.

Yet anecdotal reports often contradict the published research. They don’t pass peer review, but we can’t discount them entirely. Not everyone is lying or deluded about their experiences, believe it or not.

One explanation: it’s individual. Some people gain weight on dairy, some people lose it, some people remain at the same weight, and this can be reflected in the studies. Even if a few participants gained weight in one trial, the overall trend could be weight loss or stasis if the mean (average) effect on weight was neutral or negative. Outliers always exist. In fact, we’re generally all outliers from each other.

Another explanation: weight gained from dairy is both lean and fat – bones, muscle, and, yeah, maybe some adipose tissue. The scale never tells the entire story.

Yet another: dairy is calorically-dense, delicious, and easy for some to overeat. Particularly if you’re talking liquid dairy. Anytime you’re consuming caloric liquids, you run the risk of overdoing it. Chugging a big glass of milk might be the quickest way to eat a bunch of food at once.

Still another: among the Primal/ancestral/paleo community, dairy is a frequent topic of discussion and experimentation. People are constantly wondering about dairy’s place in their diet and “throwing it in” to see “how it affects them.” They’re adding whole milk to their post-workout meal. Incorporating a snack of aged cheese. Adding a cup of yogurt to their berries. In most cases, people are adding dairy to their diet without removing anything. They’re increasing their overall food intake. This can increase body weight.

What do you think about A1 versus A2 milk?

There’s a lot of literature to sift through, including an entire book (Devil in the Milk), so I’ll try to summarize my big takeaway.

A1 and A2 refer to two types of beta-casein (a protein) found in milk. A1 milk has mostly A1 beta-casein and A2 milk has mostly A2 beta-casein. Essentially all mammalian milk studied has beta-casein, but only certain (“newer”) breeds of cattle, like Holsteins, make significant amounts of A1 beta-casein. Goats, sheep, humans, and some other (“older”) breeds of cattle like Jerseys mostly produce A2 beta-casein. Why might this matter? What exactly is the issue?

When A1 beta-casein is digested, one of the byproducts is beta-casomorphin-7 (BCM7). BCM7 is a peptide that acts a bit like an opioid (hence “morphin”), and if it can resist complete digestion and get through the gut lining into the bloodstream, BCM7 seems to cause problems. Keith Woodford (author of Devil in the Milk) lays out the issues in a 2011 paper here (PDF).

But it sounds like intestinal permeability, or leaky gut, is a prerequisite for damage to occur.

For the first six or so months of their lives, infants have a leaky gut by design. It allows the passage of larger, beneficial protein fragments, like from their mother’s colostrum, into the bloodstream. In infants fed formula made with A1 cow milk (which is most of them), a baby’s leaky gut also allows BCM7 into the bloodstream. A study found that formula-fed infants showed elevated serum levels of bovine BCM7, especially among subjects with a genetic defect in the enzyme that breaks down BCM7. This effect was most pronounced during the first 3 months, when the gut is leakiest. High levels of bovine BCM7 were also correlated with delayed psychomotor development. The breastfed group also had BCM7 in the blood, but human BCM7; this was correlated with normal psychomotor development.

The purported links between A1 milk consumption and type 1 diabetes also appear to be mediated by the age of consumption (and thus leaky gut). A1 milk during the first two years (when the gut tends to be leakier) of life was associated with type 1 diabetes, while A1 milk consumption during the early adolescent years (when the gut tends to be less permeable) was not.

So, is it a problem? I’m not sure. Maybe for infants, although BCM7 in the blood may simply be a marker of formula feeding (which we already know to be inferior to breastfeeding). Maybe for people with leaky gut. However, I question whether A1 BCM7 makes it through intact, adult (or even teenage) gut linings. If A1 milk is a problem, I think it probably depends on your gut health – like so many other things.

Here in northern Canada, we can only get organic full fat pasteurized dairy products. I would really like to know if there is any benefit to eating them when they are all pasteurized? Or are the benefits completely mitigated by the pasteurization process…I realize it is better to have raw…just not available here….

Applying a firm latch directly to the animal’s protruding, leaking teat with your mouth is the surest way to get untouched, pure, unprocessed dairy, but that’s the ideal (well, something like the ideal) that few of us will ever attain.

Here’s how it works out for me. My butter is mostly grass-fed, but not organic. My yogurt is organic and pasture-fed, but not completely grass-fed. My Greek yogurt is conventional and presumably not pasture-fed. My cream is pasture-fed and organic, but not fully grass-fed. My cheese is sometimes raw and grass-fed, sometimes just grass-fed, and sometimes neither; it’s rarely organic. So it’s not a nice linear continuum with raw at the desired beginning. I make choices based on what’s available and what dairy food I’m actually buying. I’m not wedded to any single label.

I don’t stress too hard about raw dairy because I’m not drinking fluid milk. Raw milk is where most of the benefits appear. Raw whey, for example, is pretty good at boosting glutathione status when you eat it.

Instead, I go for fermented dairy – cheese, yogurt, the occasional batch of kefir – and dairy fat – cream and butter. With those foods, the raw aspect, while a nice bonus, isn’t all that crucial. That they are grass-fed or pasture-fed is probably the most important factor I’m looking for. Plus, remember the vast majority of those studies I mentioned last week linking full-fat dairy to various health benefits were referring to pasteurized, standard dairy, not raw dairy. Raw dairy likely isn’t necessary to get the benefits, at least not all of them.

Can you discuss the possible relation between dairy products and metabolic bone disease? As you know, the USA consumes more dairy products than any in the world, and yet have the highest incidence of Osteoarthritis.

Actually, the US ranks 16th in dairy consumption per capita, well behind most Northern European and some Eurasian countries. Furthermore, while Nordic countries like Sweden and Finland get most of their dairy from milk, and Greece and Switzerland get most of theirs from cheese, the dairy situation in the United States is a little different.

We’re drinking less milk than ever.

We eat the most ice cream in the world (as of 2011, at least). There are very few bone-building nutrients in ice cream.

We’re eating less butter and more “butter.” And the butter we do eat tends to be the alabaster, factory-farmed variety low in bone-supportive vitamin K2.

But your overall point that we eat a lot of dairy and still have poor bone health is sound, and this is simply evidence that calcium is not enough to ensure good bone density. Vitamin D status, vitamin K2 intake, even the amount of protein you eat impact the health of your skeletal system. Lifting weights and just staying active enough and moving your body against gravity on a regular basis improve bone density. Sitting around on cushioned sofas using only enough musculature to follow the screen with your eyes and cram chips into your mouth provides insufficient stimulus for maintenance of bone density. You aren’t working against gravity. Gravity is at least acting upon you (can’t say the same for astronauts in space who end up losing tons of bone and muscle), but you aren’t acting back.

Post workout, you want inflammation to be high, because the higher the inflammation, the stronger the recovery (I learned this from you, Mark). Low-fat dairy = inflammation and insulin spike, and protein. So non-fat greek yogurt post workout = best PWO snack ever?

Interesting way of thinking! I see where you’re coming from, but I don’t think heaping even more inflammation (from dietary input, no less) on top of the inflammation created by an effective training session will help. All the inflammation you need should and will come from the actual training. It’s not that “inflammation is good post-workout.” It’s that “training-induced inflammation is necessary for the training effect.” It’s a balance. Upsetting that balance in either direction could impair the results you’re expecting.

Insulin spike, post-workout? Sure, that’s helpful for shuttling in nutrients, particularly if you’re looking to increase muscle mass and restore glycogen levels as quickly as possible. The low-fat Greek yogurt might be “better,” but not because it’s increasing inflammation above and beyond what you’re already get from the workout.

I have heard that if you are gluten intolerant you should leave milk alone also. Is this true?

If your gluten intolerance is accompanied by elevated intestinal permeability (or “leaky gut”), you might want to try a period of dairy avoidance. A leaky gut can allow partially digested proteins from the food you eat pass into your bloodstream where your immune system reacts, and dairy contains potentially reactive proteins (especially casein and related byproducts like the aforementioned BCM7).

Though the evidence isn’t totally clear, gluten may increase intestinal permeability in everyone, celiac, gluten sensitive, and non-gluten sensitive alike by stimulating the release of zonulin, the compound that toggles intestinal permeability. It’s not a problem for everyone, because their immune systems can take care of any invading proteins without it developing into an inflammatory issue or an autoimmune attack on their own cells.

Try dairy. Just be careful with it. And don’t eat dairy if you’ve been eating gluten recently, especially if you’ve got a confirmed sensitivity to gluten.

That’s it for today, folks. Thanks for reading – and asking! Let me know if you have any other dairy-related questions.

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