My Vegan friend tells me that dairy products and cow milk are actually unhealthy.
He says that drinking milk increases the risk of getting cancer and that it actually impedes the bone's intake of calcium due to it being acidic.
Is consuming dairy products (in normal doses) unhealthy?
EDIT: The information I found online seemed conflicting. I also had trouble finding "neutral" sources of information.
There are several issues regarding dairy that have to be taken into consideration.
One is the link between casein and cancers. I have heard a presentation from the author of some of the prominent studies on the subject, and have reduced my own family's intake of dairy based on findings. An example of another author's findings is this paper, which concludes
The milk protein, casein, promotes the proliferation of prostate cancer cells such as PC3 and LNCaP.
Secondly is the fact that many adults lose the ability to digest lactose, which happens by slow loss of the enzyme on the intestinal brush border. Many don't realize it because of the slow onset. Symptoms of gas and diarrhea/constipation and abdominal pain are common, because the bacteria in the late gut DO digest it and produce quite a bit of gas, and it serves as an osmotic laxative.
Third, there are conflicting studies on the health impact of fat in milk. Generally, saturated fats from animal sources are advised to be avoided due to increasing cardiovascular risk via cholesterol levels. However, some studies have suggested full fat milk is actually better than skim in terms of health impact. Verdict is still out on that.
In short: According to several recent systematic reviews of studies, milk consumption is not associated with significant side effects, increased mortality, cancer, osteoporosis, heart disease or stroke.
very few adverse effects have been reported.
milk and dairy intake was inversely associated with colorectal cancer, bladder cancer, gastric cancer, and breast cancer, and not associated with risk of pancreatic cancer, ovarian cancer, or lung cancer, while the evidence for prostate cancer risk was inconsistent.
There was no consistent association between milk or dairy intake and cardiovascular disease, coronary heart disease or stroke
Food Sources of Saturated Fat and the Association With Mortality: A Meta-Analysis (PubMed, 2013)
...high intakes of milk, cheese, yogurt, and butter were not associated with a significantly increased risk of mortality compared with low intakes.
Milk and acid-base balance: proposed hypothesis versus scientific evidence (PubMed, 2011)
Recently the lay press has claimed a hypothetical association among dairy product consumption, generation of dietary acid, and harm to human health. This theoretical association is based on the idea that the protein and phosphate in milk and dairy products make them acid-producing foods, which cause our bodies to become acidified, promoting diseases of modern civilization. Some authors have suggested that dairy products are not helpful and perhaps detrimental to bone health because higher osteoporotic fracture incidence is observed in countries with higher dairy product consumption. However, scientific evidence does not support any of these claims.
Consumption of total dairy products and cream was not significantly associated with the risk of hip fracture. There was insufficient evidence to deduce the association between milk consumption and risk of hip fracture. A lower threshold of 200 g/day milk intake may have beneficial effects, whereas the effects of a higher threshold of milk intake are unclear.
Disclaimer: My conclusion is not that milk is healthy and I am not trying to encourage anyone to drink it. I just haven't found convincing evidence that it is unhealthy.
