Probably the only thing that is debated in society as much as the origins of Egyptian pyramids is dairy milk. You’ve heard it quadrillion times: greens are healthy and processed foods are not. But what about milk? Here come the questions and controversies. The reality is that the information provided by nutritionists on  Instagram, advice from our parents, in pseudo-medical articles online are too conflicting. “It is calcium-rich and promotes healthy bones” or is it ‘’full of growth hormones,  antibiotics and causes inflammation in the colon’’?

Let’s face some nutritional facts first: milk is indeed rich in protein, vitamins and minerals. It is a source of phosphorus and vitamin B12, which is found almost exclusively in animal foods. ¹ Dairy products are also one of the main sources of riboflavin (vitamin B2) in your diet.² Fat-saturated milk provides as many as 400 different types of fatty acids.³Studies also show that dairy may lower blood pressure: the unique combination of calcium, potassium, and magnesium in milk is responsible for this effect.⁴ Finally, milk is also rich in easily absorbable calcium, which is associated with higher bone density.⁵ However, the large meta-analysis shows that milk does not reduce the risk of fractures.⁶

This sounds pretty good, right? However, you might not be surprised to find out that almost all the beneficial nutrients mentioned above can be easily sourced in other even more nutritious foods like salmon or leafy greens. Other dairy products, like greek yoghurt or kefir, can be a better option for gut health as they contain probiotics and have a lower concentration of lactose. ^7,8

Now, let’s look at the other side of the coin. First of all, lactose intolerance is not a drill: around 65% of the world's population is affected by it. Unpleasant symptoms may not be limited to just diarrhoea and blemishes.⁹ Even those who tolerate lactose can face the consequences of drinking dairy milk on a regular basis. Numerous studies show that milk can trigger allergy, asthma, and eczema, it may cause intestinal bleeding in 40% of infants leading to iron deficiency and increase the risk of prostate cancer. ^10,11,12

Of course, we cannot ignore the effect of milk on hormonal health. Milk is the main food that the cow mother provides to her calf, thus it contains large amounts of growth hormone, for example, IGF-1. Large amounts of IGF-1 spike the insulin, which causes the liver to produce even more growth hormone. An abundance of IGF-1 may also lead to an increased risk of diabetes and increased triglycerides.¹³ Dairy also boosts male sex hormones, androgens. Increased levels of both androgens and insulin can cause hormonal imbalance and subsequently, hormonal acne and menstrual irregularities. ¹⁴

So, what is the verdict? To drink or not to drink? For people with lactose intolerance, hormonal imbalances and diseases, like PCOS, dairy milk is a product that should be avoided. For others, consuming dairy in moderation would be a smart decision. Be aware of all the mentioned risks, make sure you know where your milk is sourced from (organic, ethical farms without the use of antibiotics and other pharmacological interventions) and skip the highly processed milk chocolate or sugary yoghurts. And remember: it’s better to undergo an examination, do the necessary tests and consult your GP or nutritionist before making any dietary decisions. 

References:

1. Pawlak R, Lester SE, Babatunde T. The prevalence of cobalamin deficiency among vegetarians assessed by serum vitamin B12: a review of literature. Eur J Clin Nutr. 2014 May;68(5):541-8.
2. Powers HJ. Riboflavin (vitamin B-2) and health. Am J Clin Nutr. 2003 Jun;77(6):1352-60.
3. Månsson HL. Fatty acids in bovine milk fat. Food Nutr Res. 2008;52.
4. Engberink MF, Hendriksen MA, Schouten EG, et al. Inverse association between dairy intake and hypertension: the Rotterdam Study. Am J Clin Nutr. 2009 Jun;89(6):1877-83.
5. Cashman KD. Calcium intake, calcium bioavailability and bone health. Br J Nutr. 2002. 87 Suppl 2:S169-77.
6. Bischoff-Ferrari HA, Dawson-Hughes B, Baron JA, et al. Milk intake and risk of hip fracture in men and women: a meta-analysis of prospective cohort studies. J Bone Miner Res. 2011 Apr;26(4):833-9.
7. Dennis A Savaiano, Lactose digestion from yogurt: mechanism and relevance. Am J Clin Nutr. 2014, 99 (5): 1251S–1255S.
8. Nielsen B, Gürakan GC, Unlü G. Kefir: a multifaceted fermented dairy product. Probiotics Antimicrob Proteins. 2014 Dec;6(3-4):123-35.
9. Malik TF, Panuganti KK. Lactose Intolerance. [Updated 2022 May 16]. StatPearls. 2022.
10. Ho MH, Wong WH, Chang C. Clinical spectrum of food allergies: a comprehensive review. Clin Rev Allergy Immunol. 2014 Jun;46(3):225-40.
11. Ziegler EE. Adverse effects of cow's milk in infants. Nestle Nutr Workshop Ser Pediatr Program. 2007;60:185-199.
12. Song Y, Chavarro JE, Cao Y, et al. Whole milk intake is associated with prostate cancer-specific mortality among U.S. male physicians. J Nutr. 2013 Feb;143(2):189-96.
13. Schrezenmeir J, Jagla A. Milk and diabetes. J Am Coll Nutr. 2000 Apr;19(2 Suppl):176S-190S.
14. Melnik BC. Diet in acne: further evidence for the role of nutrient signalling in acne pathogenesis. Acta Derm Venereol. 2012 May;92(3):228-31.