Milk

Milk is a fascinating topic, because it is the main source of nutrients for many species when they are young. Milk content varies from species to species to meet the specific needs of newborns. This raises a lot of questions. What is in milk that makes some species grow so fast? Why doesn’t a mother produce milk indefinitely for her children?  What happens when one species drinks the milk of another species? 

What’s in Dairy Milk? 

Along with vitamins and minerals, dairy milk contains many growth hormones such as Insulin like Growth Factor (IGF-1). Research is still emerging and shows the human body can digest a lot of this hormone. However, still trace amounts can be found. IGF-1 is still spiked in individuals drinking milk. This is because it contains animal protein which I have detailed how that impacts IGF-1 in the protein article. 

The latest research also shows that many food products including milk contain microRNAs. These microRNAs can turn on or off certain protein synthesis by stopping messenger RNAs. MicroRNAs could also impact the next generation by entering a sperm or egg (Greger, 2023, p. 519). Milk contains a heavy number of microRNAs including microRNA-148a which allows for the continuous activation of mTOR by suppressing deactivating components. (Greger, 2023, p. 529). When the enzyme mTOR is activated, it may suppress autophagy. (Greger, 2023, p. 524-25). Autophagy is your body’s cleaning mechanism, a way for it to get rid of not only fat stores, but also old protein molecules, organelles and more that are not functioning properly anymore. Baby calves do need quicker aging in the beginning of life. There have been many studies showing a positive correlation between milk consumption and prostate cancer. (Greger, 2023, p.529).

In a research analysis milk was found to increase hip fractures. One theory for this is because of all the D-galactose found in milk. D-galactose is normally broken down by the body, but in some that are genetically defective and cannot break it down, osteoporosis is as follows. Therefore the theory is that having a plethora of D-galactose may not be appropriate for anyone 1,2. Modern dairy cows are also genetically improved cows can have very large amounts of estrogen and progesterone in their milk.

Phytoestrogens in soymilk do not lead to lower men's testosterone levels. Canada has changed their food recommendation guidelines to include more plants and deemphasizing milk. 

Book Sources

Greger, M. (2023). How not to age. Flatiron Books.