I’ll admit it: Out of all the variables in the China Project, dairy is the one I’ve been most eager to analyze. Not because I’m a dairy lover myself (I haven’t touched it in years) or because I’m secretly a billionaire milk tycoon with my own thousand-acre Holstein farm (au contraire; I’m strangely phobic of cows). In his book, T. Colin Campbell makes such a compelling case about casein (a milk protein) as a cancer-promoting agent that I’m left wondering: Does the China Study data shows an equally convincing link between dairy and disease?
After all, the counties studied in the China Project weren’t eating the hormone-laden, antibiotic-stuffed, factory-farmed dairy we find in most stores. Their dairy was from pastured animals—typically sheep, goats, or yaks along with cattle—raised on natural diets in rural areas. As best I can deduce, milk products were neither pasteurized nor homogenized. This means that any connections we find between dairy and mortality variables are probably from dairy itself—not the nastiness that accompanies the dairy Westerners are more familiar with. This could be one of our best opportunities for studying dairy consumption in its raw, natural state. Yeehaw!
(Note: If this is your first visit to my site and you’re on a quest for China Study information, you may want to start with the earlier posts in this series:)
- What the China Study says about meat and disease
- What the China Study says about fish and disease
- What the China Study says about eggs and disease
Dairy consumption in rural China
First, the bad news—from a scientific standpoint, at least. Only three out of the 65 counties in the China Project consumed any noteworthy amount of dairy at all. The rest were completely dairy-free or consumed dairy only a handful of times per year. That means our sample size of hardcore dairy eaters is tiny, and drawing any conclusions about dairy consumption is trickier than if we had lots of dairy-eating regions to examine.
But there’s some good news, too. Two of the counties that did eat dairy ate a lot of it—856.5 grams per day for Tuoli (just shy of 2 pounds!) and 147 grams per day for Xianghuang qi (about a third of a pound). In terms of diet, both of these places are proverbial black sheep in China, making them quite interesting as case studies. And because these regions consumed so many milk products in contrast to everyone else, any correlations genuinely tied to dairy should be pretty dramatic.
Baoqing county, the third highest consumer of dairy, ate about 19.1 grams of milk products per day. Not a whole lot, for sure, but we should keep an eye on this county as well when looking for links with disease.
A tad more info on these places for anyone who’s curious:
Tuoli county. Located at the tippy-top of northwest China in the Uyghur region—a straggler county on the map, much farther west than any other area studied in the China Project. The Tuoli get over half of their daily calories from dairy products (holy cow, literally; this is even more than Americans eat) and are quite fond of yogurt. They consume very few vegetables, fruits, or nuts, but do eat a significant amount of wheat flour.
Xianghuang qi county. Located in inner Mongolia. Local cuisine includes mutton and dairy products—especially yogurt, fermented milk, Mongolian milk tea, butter, and cheese—as well as oats and buckwheat. Vegetables haven’t been a big part of their menu until quite recently. You can read more about the diet of this region at China.com.
Baoqing county. Located at the northernmost and easternmost spot out of all the counties studied. These folks are one of our highest egg eaters, eat moderate amounts of meat, and consume wheat as their primary grain.
Dairy consumption in rural China
In China, dairy intake ranged from zero grams per day to 856.5 grams per day, as mentioned earlier. Since so few counties consumed milk products, our correlations are strongly swayed by the habits of the two dairy-eating regions. Those include snuff use (correlation of +98), meat eating (+52) and wheat intake (+35). Dairy-eating people also tended to be heavier and taller than other Chinese citizens (+34 and +23, respectively). Although the additional fat and protein from dairy foods could be responsible for a bigger body size, inhabitants of these regions tend to be ethnic minorities in China, and it’s possible they have larger builds genetically.
Dairy intake correlates positively with HDL or “good” cholesterol (+29), but not with LDL or “bad” cholesterol (-15). And in terms of general diet composition, dairy-eating regions had a low intake of fiber (-28), soluble carbohydrates (-23), and plant protein (-25) but a high intake of total protein (+80), animal protein (+99), total fat (+78), and total calories (+62).
So does all this animal protein and fat equate to more chronic diseases, especially cancer? Let’s take a look-see. Surprisingly, there’s only one statistically significant correlation, so I’ll list even the weak correlations to give the full picture.
NEGATIVE CORRELATIONS (more dairy = fewer of these diseases)
Liver cirrhosis: -21
Peptic ulcer: -19
Other metabolic diseases: -17
Rectal cancer: -14
Penis cancer: -13
Colorectal cancer: -9
Death from all causes: -9
Other heart disease: -9
Bladder cancer: -8
Diseases of the blood and blood-forming organs: -7
Colon cancer: -6
Liver cancer: -4
Neurological diseases: -2
POSITIVE CORRELATIONS (more dairy = more of these diseases)
Hypertensive heart disease: +30*
Stomach cancer: +10
Breast cancer: +9
Oesophageal cancer: +8
Death from all cancers: +7
Myocardial infarction: +6
Brain cancer: +4
Cervix cancer: +2
Rheumatic heart disease: +1
Remember that, for both positive and negative correlations, smaller numbers are essentially insignificant. Zero is perfect neutrality, but we rarely get a statistical zero in the real world—especially when we have a maximum of 65 data points to work with. With the exception of hypertensive heart disease, none of the positive correlations appear meaningful, and perhaps only lymphoma and “other metabolic diseases” warrant further study among the negative correlations. (Liver cirrhosis and peptic ulcers, the other marginally strong inverse trends, most likely have non-nutritional causes.)
Hypertensive heart disease
Unlike atherosclerosis, hypertensive heart disease is not caused by plaque building up on arterial walls. With this condition, chronic high blood pressure (AKA hypertension) forces the heart to work harder, leading to a thickening of the muscle. Does something about dairy consumption raise blood pressure and lead to a big heart (the diseased kind, not the generous kind)?
Looking solely at the “hypertensive heart disease” variable, we can see that a few other factors outshine the dairy correlation. Daily salt intake correlates at +37, salt intake plus urine salt correlates at +50, weight correlates at +33, and wheat flour correlates at +54. The “other foods” category—which includes vinegar, MSG, baking powder, tea, and melon seeds—has a correlation of +51. Negative associations include rice (-45), yearly green vegetable intake (-36), steamed bread and pancakes (-57), and daily alcohol consumption (-27).
Since we really only have three counties that consumed significant levels of dairy, it won’t be easy—and maybe not even possible—to pinpoint the role of dairy itself in hypertensive heart disease. Here’s our untampered graph, charting every county that reported hypertensive heart disease mortality.
Kinda sparse, huh?
There certainly is an upward trend amongst dairy-eating counties, but let’s face it: We’re basing that on two measly dots. Dots that, more importantly, represent complete dietary rebels in this data set. Along with consuming milk products, our two dairy-eating regions have some other nutritional divergences compared to the rest of China. For instance:
- Both significantly fewer vegetables than any of the other 65 counties in the China Project: Tuoli only consumes green vegetables an average of two times per year (!) and Xianghuang qi consumes them 24 times per year, about twice per month. The average intake for all counties is closer to 200 times per year. Could lack of green vegetables, which we already know correlates with hypertensive heart disease, be raising these county’s rates?
- Tuoli consumes a whoppin’ average of 172.5 grams of protein per day, 134.55 of which come from animal sources. Even a gym-rat bodybuilder might consider that excessive. No other county comes close to that intake; the next highest is 90.8 grams per day. Could an uber-high protein intake contribute to hypertension?
- Tuoli also consumes far more fat than any other county: 185.8 grams per day. Wowza. The average for all of China is 44.2. Is a high fat intake playing a role?
- As you’d expect from a very high-fat diet, the Tuoli eat more calories per day than any other county studied in the China Project: 3704 on average. No, that’s not a typo. They’re also the heaviest county among the 65. Do these folks have higher rates of obesity, which surely is a risk factor for hypertensive heart disease?
- Both dairy-eating counties had a higher levels of dietary and urine sodium than average. This one’s a no-brainer; excess sodium is a well-known cause of high blood pressure and, consequently, hypertensive heart disease.
- Both dairy-eating counties eat significant quantities of wheat flour, which—as you shall soon see—has some really mind-bogglingly crazy associations with cardiovascular disease. Seriously, it’ll knock your socks off. But that’s a few more posts away.
And despite eating almost two pounds of dairy a day, Tuoli’s hypertensive heart disease mortality (far right dot) is still surpassed by two other counties—both of which eat no dairy at all. And the disease rate for Xianghuang qi county is right smack dab in the middle of the data set range, ranking behind six dairy-free counties. Even if dairy is a factor in developing hypertensive heart disease, which we can’t say for certain, it’s clearly not the only contributor.
At any rate, I’m not interested in vilifying nor vindicating dairy here; I’m just exploring alternative possibilities for the correlation between milk products and hypertensive heart disease.
- China’s dairy eaters don’t have significantly more cancers, myocardial infarction, stroke, and so forth than the dairy-free regions.
- Dairy’s only significant mortality correlation, hypertensive heart disease, may be related to any number of variables we don’t have enough data to tweeze apart. (Lack of vegetables, excess sodium, high body weight, and high caloric intake, to name a few.)
- Despite T. Colin Campbell’s findings with the milk protein casein spurring cancer in lab rats, there does not seem to be a correlation between high dairy consumption and cancer in the China Study data.
Are you as fascinated as I am with the Tuoli’s incredibly high-fat, high-protein, vegetableless diet? Are you wondering what their disease rates are, how long they live, and whether they’re any healthier or sicker than the Chinese eating plant-based diets? I sure am. Up next will be a mini-post about the Tuoli specifically, including answers to the aforementioned questions. This should be pretty interesting!