Have there been any studies comparing milk consuming countries against mainly vegan countries? [closed]

Question

According to Vegetarian, vegan diets and multiple health outcomes: A systematic review with meta-analysis of observational studies (Critical Reviews in Food Science and Nutrition, 2017, both vegan and vegetarian diets can be associated with better health outcomes:

This comprehensive meta-analysis reports a significant protective effect of a vegetarian diet versus the incidence and/or mortality from ischemic heart disease (-25%) and incidence from total cancer (-8%). Vegan diet conferred a significant reduced risk (-15%) of incidence from total cancer.

Next, in some studies: Milk and dairy products: good or bad for human health? An assessment of the totality of scientific evidence (Food and Nutrition Research, 2016, they have found association between milk/dairy consumption and reduced risk of some chronic diseases:

The totality of available scientific evidence supports that intake of milk and dairy products contribute to meet nutrient recommendations, and may protect against the most prevalent chronic diseases, whereas very few adverse effects have been reported.

Is it possible that in countries with lot of vegans but also with high milk consumption, the health effects of vegan diet have been overrated and should be actually ascribed to milk consumption? Is it possible to find out this by comparing countries with lot of vegans and countries with high per capita milk consumption and the incidence of various diseases in these countries?

Answer 1

From the data about per capita milk consumption and veganism in various countries and prevalence of various diseases in those countries, you can't make any reliable conclusions about the effect of milk and veganism on health. On the other hand, you can check for such association in studies in milk consumers or vegans. So, the studies need to include only the actual milk consumers or vegans and not the whole country populations.

At least for adults, milk is probably not especially beneficial or harmful for health. For example, the latest scientific evidence confirmed neutral or slightly beneficial associations between dairy products and risk of cardiometabolic diseases (Current Nutrition Reports, 2018). According to an answer on Skeptics SE, milk consumption is not especially beneficial or harmful for bone health. But if you check the below pictures, you can see that in countries with high milk consumption (for example, in Europe), there is a high prevalence of bone fractures and cardiovascular disease. And Russia has a low per capita milk consumption but high prevalence of cardiovascular disease. This means you can't make any logic from the data "by country."

Here are some data for veganism by country from another answer:

• Poland: 7% (2,688,000 people, 2016)
• Israel: 5% (421,000 people, 2014 and 2015)
• Sweden: 4% (388,000 people, 2014)
• Brazil: 3% (6,333,660 people, 2018)
• United States: 3% (7,588,000 people, 2018)
• Switzerland: 3% (252,033 people, 2017)
• Japan: 2.7% (5,875,000 people, 2014)
• Canada: 2.3% (835,000 people, 2016)
• India: 1.6% (2005–06)

In this 2017 systematic review of studies veganism was associated with lower risk of cardiovascular disease. But again, if you check the above data about the percent of vegans in some countries with the Picture 3 that shows prevalence of cardiovascular diseases in various countries, you can't see any logic. For example, there are relatively lot of vegans in Poland but there's also a high prevalence of cardiovascular disease there. There is also a lot of milk consumers in Poland, which again shows that you can't make any conclusions from data "by country."

Picture 1. Milk production and consumption by country (source: Wikipedia) (here's an ordered list of 100 countries).

Picture 2. Prevalence of hip fractures by country. Red = high, Orange = medium, Green = low (source: Wikipedia)

Picture 3. Ischaemic heart disease prevalence by country (Red = high, Yellow = low) (source: Wikipedia)