With increasing reports of gastrointestinal issues around the globe, the rise in allergies, and talk about whether or not cow's milk is appropriate for human consumption, cow's milk and dairy foods are getting pointed at with an accusatory finger.
It can be pretty tough to figure out what to believe - there is so much information available to us, yet not all of it is science-based. If you're not sure whether you should be drinking dairy, I've spent many hours trawling through the research for you. I hope some of your biggest questions around cow's milk will be answered by the end of this blog.
Before we get started, it's important to know that removing any food from your diet should be done with great care. This is the because the different food groups:
1) Fruit & vegetables
2) Breads & cereals
3) Meat & meat alternatives
4) Dairy and dairy alternatives
provide a different range of nutrients mostly distinct from the others. Therefore, reducing the variety of foods you eat can also reduce the nutritional quality of your diet if not done properly.
So, before making such decisions and to ensure you are as fully informed as possible, here are a few things to consider before ditching the dairy.
First of all, it's important to know what cow's milk and dairy products are, and their significance for New Zealand. Milk and milk by-products (otherwise known as dairy foods) are one of the largest export products in New Zealand. They make up around 20% of our total earnings from export goods and services. A whopping 95% of all the milk we produce is exported to other countries.
In very basic terms, milk is produced by dairy cows through the consumption and digestion of grass. Milk is then pasteurised for safety (heated to destroy bacteria) and homogenised for taste and texture (stops the fat separating into a layer on top). The homogenisation process also allows the fat content to be adjusted e.g skim milk vs full cream milk. Removing the fat also means there is more room for other nutrients, which is why lower fat milks have more protein and calcium. Milk is also used to create cheese (separating the curds and whey proteins), yoghurt (adding probiotics), butter (using the fat from the milk) and other products, such as cream.
Nutrition in Cow's Milk vs Milk Alternatives
Cow's milk is objectively very nutritious. Cow's milk is naturally high in protein and minerals, such as calcium and phosphorus (very important for healthy bones). It is also a good source of vitamin B12 (nerve & blood health) and dairy products are one of the few foods that provide vitamin D (brain & immune health).
There is a growing range of milk alternatives on the market. Below is a nutritional comparison of 100mls of cow's milk and milk alternatives available in the market. As many milk alternatives are not naturally high in protein, vitamins, or minerals (unlike cow's milk), these nutrients are added into the product (fortfication). After fortification, some products can be good nutritional alternatives to cow's milk.
Make sure you check the labels and pick the best alternative you can - there will be some nutrient variation across brands as well.
When picking your milk alternative, select a milk that's higher in protein (has at least 3g/ 100ml of product) and calcium (at least 100mg / 100ml). Additional vitamins such as vitamin D and B12 are also great to look for. Some milk alternatives have their own nutritional bonus e.g oat milk has beta-glucans to help lower cholesterol and hemp milk contains small amounts of omega-3 for brain health. Every little bit can add up to improve the nutritional content of your diet. If you're worried you might not be getting enough protein, calcium, or other nutrients from your milk choice, it's really important to speak to a dietitian or nutritionist to make sure your diet is nutritionally complete.
From a nutritional perspective, we can see that cow's milk is a highly nutritious food. We can also see that are there some suitable milk alternatives available, so with some planning and guidance you can get all the nutrients you need if you decide not to have cow's milk.
The next topic is based on questions I often get during my nutrition consults.
Growth Hormones in Cow's milk
It is true that there are growth hormones in cow's milk. However, it's important to know the distinction between naturally occuring hormones in milk (such as IGF-1) and hormones that are used in dairy farming (such as rBST). Hormone use in dairy farming is banned in New Zealand, so these concerns are not applicable to our locally produced dairy foods. However, there is some research on naturally occuring hormones in cow's milk which is quite interesting. I'm going to get a touch heavy on the research in the next few paragraphs, so bear with me.
Growth hormones are pretty much exactly what they sound like - hormones which stimulate growth. They occuring naturally in cow's milk to help calves grow. It's theorised that naturally occuring hormones in cow's milk may play a role in the development of certain types of cancer in humans. This is because hormonal imbalances can present with some types of cancers. However, there is no evidence that cow's milk actually causes cancer. Currently, some research shows only a correlation, where people who consume more cow's milk also have higher incidences of some types of cancers. However, the science doesn't agree here. Whilst there have been correlations noted between high milk consumption and prostate , breast, and ovarian cancers , other studies have suggested that high cow's milk intakes are protective against breast  and colorectal cancers . There is also evidence that cow's milk and dairy products may help with weight management and reduce the risk of type 2 diabetes .
Overall, having the recommended 2-3 serves of cows milk products everyday (e.g 40g cheese, 250mls milk, 1 x 150g pottle yoghurt) will not increase your risk of cancer. You can enjoy your cow's milk and dairy products in peace.
Intolerances, Cow's Milk Allergies & A2 milk
Finally, there is one more question that crops up frequently during my nutrition consults. Is cow's milk giving me a funny tummy? The answer to this is very much a case-by-case basis. Here are some reasons why cow's milk could be causing some tummy troubles:
1) A cow's milk allergy. This is very unlikely in adults, but not impossible. A food allergy is an immune-response to certain proteins in food. The body mis-identifies these proteins as an "enemy invader" that can cause you harm. Your immune system will create antibodies which are sent out to attack and destroy the "invader". These antibodies attach themselves to body cells that have been exposed and release chemicals such as histamines. It's these chemicals that cause the allergic symptoms. For example, if we have hay-fever, we take anti-histamines to stop our nose running and our eyes itching.
A food allergy can range from mild to severe (anaphylaxis) and can present as hives, swelling of the throat, trouble breathing, vomiting, nausea, stomach pains, and diarrhoea . Symptoms usually come on very quickly and immediate medical attention is required. Cow's milk allergies occur mostly in infants and is very rare in adults, with less than 0.1% of the adult population presenting with cow's milk allergy .
2) You could have a cow's milk intolerance. A food intolerance is usually an inability to properly digest the sugars found in food. It's not uncommon to have an intolerance to lactose, which is the sugar found in cow's milk. An intolerance usually presents a number of hours after eating the food as it travels through the digestive tract. It can cause bloating, cramping, flatulance, and diarrhoea. Symptoms occur because the person does not produce enough lactase, which is the enzyme that breaks down the lactose. An intolerance is not life-threatening or immediately harmful, though it can cause a lot of discomfort. Around 15% of people of European descent have some level of lactose intolerance, and as many as 100% of Indian or Asian peoples. . Depending on their tolerance level, most people can consume a small amount of lactose before experiencing any symptoms. Milk products such as yoghurt and cheese contain less lactose than milk, so these foods are often better tolerated. If you experience digestive upset after drinking cow's milk, you may have a lactose intolerance. The most reliable way to test for a lactose intolerance is to undertake a food challenge, where you remove lactose-containing foods from your diet for a set length of time before reintroducing it and monitoring symptoms. This must be done with the guidance of a nutritionist or dietitian, as you will need to make sure you are still meeting your nutritional requirements. Lactose intolerances are easy to manage in New Zealand. You can choose to consume lactose-free milk (which is actually milk with lactase added to it), or you can chose another suitable non-cow's milk alternative.
3) Lastly, you might have an A2 protein intolerance. This is a tricky one to navigate, as there isn't much evidence around A2 intolerances, and the evidence we do have is quite controvertial. A2 milk contains only the A2 type protein, instead of both A1 and A2 like most cow's milk. There is a theory that due to the slight difference in structure of the A1 protein compared to the A2 protein, the digestion of A1 milk forms a peptide called BCM-7. BCM-7 is theorised to cause digestive problems, among other health concerns. Studies investigating links between A1 proteins and disease have been heavily criticised in the scientific community due to bias or poor design . A major problem with studies finding that A2 milk results in fewer tummy troubles than A1 milk is that they have few participants [11, 12]. This means that findings are not applicable to the general population. It also means that it's not always possible to establish a statistically significant difference between drinking A1 & A2 vs A2 only milk . Whilst it's clear that we need more evidence from larger studies with objective measures of digestive symptoms (many studies are self-reported), there seems to be more to learn. Nutritionists and dietitians should not disregard A2 milk as a possible solution to digestive discomfort. Drinking A2 milk causes no harm, so if all other potential causes have been investigated, it seems logical to give it a try.
Cow's milk is a nutritious beverage that many individuals can enjoy every day. Cow's milk is safe to consume, is high in protein, vitamins and minerals, and is a valuable addition to a healthy diet. If you are experiencing gastrointestinal symptoms upon drinking cow's milk, reach out to a nutritionist or dietitian to see if milk alternatives might be a solution for you (I'm here to help!).
When you read articles about cow's milk (or about food in general) be weary of sensationalist headlines or articles. One scientific study is not enough to give us all the information we need. Controversial findings can also be presented by the media or by individuals on social media without considering all the facts.
If you've got any questions about the sustainability of cow's milk, dairy products, and milk alternatives then keep an eye out for my next blog: How to Eat Sustainably in New Zealand.
1. Ganmaa, D., Li, X.M., Qin, L.Q., Wang, P.Y., Takeda, M. and Sato, A., 2003. The experience of Japan as a clue to the etiology of testicular and prostatic cancers. Medical hypotheses, 60(5), pp.724-73
2. Ganmaa, D. and Sato, A., 2005. The possible role of female sex hormones in milk from pregnant cows in the development of breast, ovarian and corpus uteri cancers. Medical hypotheses, 65(6), pp.1028-103
3. Knekt, P., Järvinen, R., Seppänen, R., Pukkala, E. and Aromaa, A., 1996. Intake of dairy products and the risk of breast cancer. British Journal of Cancer, 73(5), pp.687-691.
4. Aune, D., Lau, R., Chan, D.S.M., Vieira, R., Greenwood, D.C., Kampman, E. and Norat, T., 2012. Dairy products and colorectal cancer risk: a systematic review and meta-analysis of cohort studies. Annals of oncology, 23(1), pp.37-45.
5. Grout, L., Baker, M. G., French, N., & Hales, S. (2020). A review of potential public health impacts associated with the global dairy sector. GeoHealth, 4(2), e2019GH000213.
6. Woods RK, Thien F, Raven J, Walters EH, Abramson MA: Prevalence of food allergies in young adults and their relationship to asthma, nasal allergies, and eczema.Ann Allergy Asthma Immunol88 :183– 189,2002 .
7. Woods, R.K., Thien, F., Raven, J., Walters, E.H. and Abramson, M., 2002. Prevalence of food allergies in young adults and their relationship to asthma, nasal allergies, and eczema. Annals of Allergy, Asthma & Immunology, 88(2), pp.183-189.
8. Swagerty Jr, D.L., Walling, A. and Klein, R.M., 2002. Lactose intolerance. American family physician, 65(9), p.1845.
9. Truswell, A.S., 2005. The A2 milk case: a critical review. European journal of clinical nutrition, 59(5), pp.623-631.
10. Kaskous, S., 2020. A1-and A2-Milk and Their Effect on Human Health. Journal of Food Engineering and Technology, 9(1), pp.15-21.
11. Jianqin, S., Leiming, X., Lu, X., Yelland, G.W., Ni, J. and Clarke, A.J., 2015. Effects of milk containing only A2 beta casein versus milk containing both A1 and A2 beta casein proteins on gastrointestinal physiology, symptoms of discomfort, and cognitive behavior of people with self-reported intolerance to traditional cows’ milk. Nutrition journal, 15(1), p.35.
12. Ho, S., Woodford, K., Kukuljan, S. and Pal, S., 2014. Comparative effects of A1 versus A2 beta-casein on gastrointestinal measures: a blinded randomised cross-over pilot study. European journal of clinical nutrition, 68(9), pp.994-1000.