Is drinking and eating dairy bad for you?
One of the primary reasons I stopped consuming dairy was because I suffered from severe acne. Milk is well-known to adversely affect acne.[1,2,3,4,5,6,7,51] (Acne can also be a result of other poor dietary factors, not just dairy.) Personally, this is compelling enough evidence against dairy to restrict or eliminate its intake.
The evidence showing health detriments of dairy makes for a strong case against dairy consumption, with dairy potentially being one of the most harmful foods if consumed in excess (though it has tough competition in society’s generally unhealthy diet).
You may have heard about the latest of such studies (Milk intake and risk of mortality and fractures in women and men: cohort studies) illustrating that high milk intake may be problematic to health, including even potentially accelerating aging. This is not the first case of milk consumption leading to bone problems, there’s a long history of concerns.
While dairy milk is touted to build strong bones, the evidence doesn’t support this claim (at least in women, more data is required for men[48,49,50]). Dairy is known to increase risk for prostate and ovarian cancers, and perhaps other cancers, infections and tumors.[7,8,9,10,11,37,41,42,43,44,45,46,47] Dairy increases incidence of diabetes.[12,13] Dairy may play a role in multiple sclerosis. Dairy can elevate cholesterol. Dairy can lead to Parkinson’s disease. Dairy can contain hormones that adversely affect health.[17,18] A protein in dairy milk, casomorphin, is also linked with health detriments including sudden infant death syndrome.[19,20]
Milk and mucus remains a controversial issue. Many people anecdotally report milk increasing mucus production, but this hasn’t been scientifically verified.[38,39] However, a theory has been proposed that mucus glands in the respiratory tract may respond to casomorphin from dairy milk, potentially stimulating the production and secretion of mucus in the respiratory glands.[28,40] At least in some people dairy milk is known and documented to increase mucus production or produce asthma-like symptoms.[28,39] It depends on the person, it depends on the milk, but the milk and mucus claim shouldn’t be dismissed entirely as an old wives’ tale.
However, moderate consumption of dairy milk in the form of an occasional glass is unlikely to cause much if any harm, but regular consumption shouldn’t be advised. While the USDA still endorses milk consumption (which isn’t well-known to provide solid health recommendations due to the politics involved), the Healthy Eating Plate & Healthy Eating Pyramid, created by nutrition experts at Harvard School of Public Health and editors at Harvard Health Publications, suggests that dairy is not essential for diet and if consumed should be limited to one to two servings per day.
Milk is non-essential for good health so long as one ensures adequate calcium intake from whole or fortified foods.[30,31] There are many foods that have higher concentrations of calcium than dairy, and there’s nothing particularly special about dairy when it comes to absorption.[33,34] Especially healthful sources of calcium include dark green leafy vegetables like bok choy, broccoli, collards, kale and mustard greens.
With all these potential risks, and with little benefit — and no benefits that cannot otherwise be obtained from more healthful foods — why consume dairy milk at all? There’s sufficient evidence to support the assertion that dairy milk is detrimental for human health and there’s no good evidence to suggest the necessity or benefit of adding dairy into a healthy diet.
In summary, dairy milk is not entirely bad, but caution should at the very least warrant its restriction if not elimination. While dairy milk is not exactly void of nutrition — it does contain some useful nutrients — it does come associated with a lot of unwanted and unhealthful baggage, and dairy is completely unnecessary for good health. Moderate consumption of one to two glasses per day may be safe to consume but may also adversely impact longevity and likely doesn’t provide additional health advantage over other healthful food sources. Based on the available evidence illustrating potential ill effects of dairy milk consumption, it may be advisable to further restrict dairy milk consumption to even less than the one to two glasses per day limit currently recommended by the Harvard School of Public Health. Some people may be able to tolerate dairy milk better than others, and some people obviously are allergic and should avoid completely. In any case, excess consumption should certainly be avoided; opposed to other healthful high-calcium foods like dark green leafy vegetables that do not require moderation or restriction.