Two highly-respected Harvard professors, Dr. Walter C. Willett and Dr. David S. Ludwig, think that North Americans don’t need to drink milk (N Engl J Med, Feb 13, 2020; 382:644-654). An earlier comprehensive review of the world’s literature came to the same conclusion (Amer J of Clin Nutr, May 2014;99(5):1217S-1222S). A majority of food scientists today question the 2015-2020 U.S. Dietary Guidelines (from the Department of Health and Human Services and the Department of Agriculture), which recommend that people over nine years old should consume three glasses of fat-free or low-fat dairy products each day. Willett and Ludwig have reviewed hundreds of studies and found:
• No evidence that drinking milk (including low-fat milk or skim milk) helps people lose weight or control their weight.
• No evidence that milk helps to control cholesterol or blood pressure, two major markers for heart attacks. The few studies that showed that dairy products help to control high blood pressure were only in people who followed a very healthful diet overall.
• No evidence that milk helps to prevent or treat diabetes.
• Evidence of increased risk for breast cancer (Int J of Epidem, February 25, 2020), endometrial cancer, and prostate cancer.
• Evidence that societies taking in the most milk and calcium have the highest rates of hip fractures (JAMA Pediatr, 2014;168(1):54-60). They also have higher growth rates in children, which may increase risk for hip fractures, lung clots, and several different cancers. Cows are bred to produce high levels of insulin-like growth factor, which increases milk production and also may promote both bone growth and cancer in people who drink that milk.
The main argument for drinking milk is its high calcium content. Milk and cheese contribute 46 percent of the calcium intake by the average American, but Willett and Ludwig found many recent studies showing that American adults do not need to take in that much milk to provide enough calcium to help prevent bone fractures. Children need calcium for building bones, but the studies fail to show that taking in extra dairy products builds stronger bones.
Health Benefits from Dairy Products?
Excess sugar in drinks and added to foods is arguably the major cause of heart disease in North America today (JAMA Intern Med, April 2014;174(4):516-24). Milk is more healthful than sugar-sweetened beverages or fruit juices, but there is no strong evidence to show that adding milk to the diet of average North Americans offers health benefits. The recent PURE Study that concluded that milk is healthful was done mostly in under-developed countries where many people did not get enough to eat. Getting any source of nutrients is more healthful than not getting enough. Willett and Ludwig believe that people in third world countries, who eat a diet based on refined carbohydrates (white rice, flour and sugar), may benefit from replacing the sugar and other refined carbohydrates in food and drinks with milk. Milk may confer more benefit to people who have a lower protein and calcium intake than people who generally have higher intakes.
Whole milk is high in saturated fats that have repeatedly been shown to increase blood levels of the bad LDL cholesterol, which is associated with increased heart attack risk. However, a review of 76 studies showed that saturated fats in foods were not associated with increased risk for heart attacks (Ann of Int Med, March 18, 2014;160(6)), and none of the milk fats in humans are associated with increased death rate (Am J Clin Nutr, Sept 2018;108(3):476-484). Red meat has been associated with increased risk for heart attacks, certain cancers and premature death, but this association may come from an immune response to Neu5Gc and/or increased colon bacterial production of TMAO, and perhaps has no link to the saturated fats.
Galactose, the Pro-Inflammatory Sugar in Milk
Milk contains galactose, a pro-inflammatory sugar that causes oxidative damage and chronic inflammation that is associated with increased risk for diabetes, heart attacks, certain cancers and bone loss (Biogerontology, 2004;5:317-25). People who drink milk have increased urine levels of 8-iso-PGF2a (a biomarker of oxidative stress) and serum interleukin 6 (a major inflammatory biomarker), and chronic exposure of mice, rats and drosophila flies to galactose caused their cells to develop signs associated with aging: shorter telomeres and DNA damage (Journal of Neuroscience Research, 2006;84(3):647-654).
When milk is fermented to make cheese or yogurt, bacteria break down the galactose (J Hum Nutr Diet, 2009;22:400-8), so they have very low levels of that harmful sugar. Several studies show that eating fermented yogurt and fermented cheeses, but not other dairy products, is associated with decreased risk for heart attacks and death (Brit J of Nutr, Dec 14, 2018;120(11):1288-1297). Cheese and yogurt have been associated with preventing heart attacks and prolonging lives (European Society of Cardiology Congress, Aug 28, 2018; J Agr and Food Chem, April 2015;63 (10):2830-9). People who ate a lot of cheese had very high levels of the healthful short chain fatty acid, butyrate, in their stool and urine, and much lower blood levels of the bad LDL cholesterol. The fermented dairy products appear to be converted by bacteria in the intestines into short chain fatty acids that prevent formation of the bad LDL cholesterol that is associated with increased heart attack risk, and encourage the growth of colonies of healthful intestinal bacteria. Another study of 27,000 people, ages 45 to 74, showed that eating cheese and yogurt lowered risk of type 2 diabetes by 25 percent (Am J Clin Nutr, April 2015).
Many recent studies show that North Americans do not need to drink milk to be healthy. I recommend that adults avoid milk because it is high in the pro-inflammatory sugar, galactose, but fermented dairy products such as yogurt and some types of cheese have very low levels of galactose and appear to be healthful. See my report on Yogurt or Cheese Instead of Milk Reduces Heart Attack Risk. If you are concerned about getting enough calcium in your diet, eat a wide variety of calcium-rich foods such as live-culture yogurt, cheeses, leafy green vegetables, whole grains, beans, and fish such as salmon or sardines.