For the dairy industry there must be some disappointment that the word ‘scary’ rhythms so well with dairy. Certainly on many dairy farms the practices are more distressing than those of meat production - and those practices can be pretty poor (i). Indeed the internet is awash with info videos with titles like ‘Scary Dairy’ telling us it is time to reconsider dairy (see link).
If you want to check out ‘good’ milk then find those smaller farmers like Stroud Micro Dairy with a real consideration to the animals and environment. However this blog is not covering those issues other than to say how animals are treated has a huge part to play in the quality of food they produce - instead I wanted to explore more whether dairy has an impact on prostate cancer.
As a child we had glasses of milk at home and school and as an adult with some years largely vegetarian I loved cheese. However, it was not until my cancer diagnosis that I reconsidered it.
So what do folks say?
The NHS Eatwell Guide recommends having some dairy as part of a healthy, balanced diet. In Canada the federal government have updated their guidelines and their new Canada Food Guide advises Canadians to eat more vegan foods and less meat. They have cut the proportion of dairy and also largely removed cheese from the guidelines (see right).
Cancer Research UK (ii) always take a fairly conservative view in terms of research and like the Dietician I saw at the hospital after my diagnosis, says: "There is not enough good evidence to prove that milk and dairy can cause cancer."
Cancer Research UK also write: “Eating and drinking milk and dairy can reduce the risk of bowel cancer. But there is no proof it increases or decreases the risk of any other cancer type”. They note, however, studies have found an increased risk of both prostate and breast cancer in people who have large amounts of dairy; “But there’s not enough good evidence for this”.
Cancer Research UK call for more research - and clearly it is needed - however as Michael Greger of Nutrition Facts points out there have been many studies (iii). For example 32 studies found an increase in prostate cancer linked to dairy. In Greger’s 7 minute video he looks at some of that research pointing out the increase doesn’t seem to be connected to calcium; non-dairy calcium sources were protective of cancer but dairy was not. It seems the insulin-like growth factor I (IGF1) in dairy is more likely one of the key factors.
One study Greger quotes shows that consuming three or more product of dairy a day after prostate cancer diagnosis had a 76% higher risk of mortality and a 141% higher risk of prostate cancer-specific mortality compared to men who consume one dairy product or less per day. He goes on to show that advanced prostate cancers thrive by up-regulating a growth enzyme called mTOC1; dairy protein boosts mTOR1 signalling higher. This makes sense as the weight gain of calves in the first year of cow’s milk feeding is nearly 40-times higher than that of breast-fed human infants. Pregnant cows release “uncontrolled bovine steroids into the human food chain”. Could this all play a role in prostate cancer?
In the 2007 World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) report “Food, Nutrition, Physical Activity and the Prevention of Cancer” it stated that there is probable evidence that diets high in calcium increase risk and limited suggestive evidence that milk and dairy products increase risk. They gave no recommendation for dairy as the prostate cancer risk conflicted with the evidence noted above by Cancer Research that there is a decreased risk with bowel cancers.
A 2011 study looked at other studies and confirmed that milk and total dairy products but not cheese or other dairy products are associated with a reduced risk of colorectal cancer. However the picture is confusing as people who drink milk exercise more, eat less meat, smoke less and have other better health behaviours. The conclusion was that it was likely to be the calcium binding with bile acids to reduce cell proliferation and promote cell differentiation. This explains why cheese wasn’t a factor and could increase colorectal cancer by increasing bile acid levels in the colon.
As noted earlier we need more research. However there are too many reports for me linking dairy to an increased risk. Indeed as I started writing this blog a new study (8th June 2022) (iv) at Loma Linda University of 28,000 North Americans, concluded: “Men with higher intake of dairy foods, but not nondairy calcium, had a higher risk of prostate cancer compared with men having lower intakes. Associations were nonlinear, suggesting greatest increases in risk at relatively low doses.” The results had minimal variation when comparing intake of full fat versus reduced or nonfat milks; there were no important associations reported with cheese and yogurt.
In his video Greger concludes that if you want to take a precautionary approach then it is best to obtain calcium through green leafy vegetables, legumes and non-dairy milks. I am with him on that and we no longer have dairy milk in this house.
What about other dairy products?
Dairy of course includes a whole host of other products some of which may have benefits and some may have less impact on cancers than others - but there isn’t enough research.
Organic pastured-fed butter is surely better than processed margarines? And organic kefir and yogurt’s are full of probiotics which can be key support for the microbiome? Goat and sheep milks are said to be easier to digest and better than cow’s milk? Some suggest unpasteurised (or raw milk) is better, others see risks?
Ghee (or clarified butter) is treated with low heat, and retains more nutrients than standard butter. The Ayurveda tradition see it as having spiritual and medicinal properties and even preventative of cancer; it is certainly gaining traction as a healthier alternative to standard butter. Organic and grass fed being favoured - it is also a useful fat that can be used at higher temperatures. See a useful article on dairy by Truly Heal here (v).
Lactose intolerance?
A further factor to consider is that each of us is different. Most infants, for example, can digest lactose, however people can begin to develop lactose malabsorption (a reduced ability to digest lactose) after infancy. It is estimated that about 68 percent of the world’s population has lactose malabsorption; this is more common in some parts of the world (like Africa and Asia) than in others. Whereas in northern Europe, many people carry a gene that allows them to digest lactose after infancy, and lactose malabsorption is less common. In the United States, about 36 percent of people have lactose malabsorption; lactose malabsorption causes lactose intolerance, not all people with lactose malabsorption have lactose intolerance.
Genetic or allergy testing can be helpful. My DNA apparently shows that I am ‘likely tolerant’ of lactose. However my hair analysis shows a ‘high reactivity’ food sensitivity to all dairy. That is not an allergy but rather a sensitivity; having food sensitivity may be uncomfortable and cause symptoms that, whilst annoying, embarrassing or even debilitating, do not have the potential to be life-threatening like those caused by food allergy. Fortunately I don’t seem to have any obvious symptoms.
Where did this leave me? Well, confused but while being largely vegan I am not afraid to occasionally have some of these dairy products.
Berries and dairy - don’t do it!
To finish I thought this was worth a mention - before diagnosis I had berries and yoghurt - and more recently occasionally organic sheep yoghurt for breakfast with those berries - we know how good blueberries are for tackling cancer! I was however rather disappointed to read this; Three Harvard studies following more than a 100,000 women for more than a decade found that those consuming the most anthocyanins (the brightly coloured pigments found in blueberries and other berries) had an 8% reduction in risk of developing high blood pressure (vi).
Indeed just 11 blueberries or 6 strawberries daily made that difference. However the moment dairy (milk or yoghurt) was added and researchers found it blocked the absorption of the berries nutrients and appeared to eliminate the blood pressure-lowering benefits of the berries.
So no more strawberries and cream? Sadly milk in tea also prevents vascular protective effects of the tea.
All this is food for thought.
Notes
(i) https://www.theguardian.com/commentisfree/2017/mar/30/dairy-scary-public-farming-calves-pens-alternatives
(ii) https://www.cancerresearchuk.org/about-cancer/causes-of-cancer/cancer-myths/can-milk-and-dairy-products-cause-cancer
(iii) https://nutritionfacts.org/video/dairy-and-cancer
(iv) https://news.llu.edu/research/new-study-associates-intake-of-dairy-milk-with-greater-risk-of-prostate-cancer
(v) https://www.trulyheal.com/have-you-been-told-to-avoid-dairy/
(vi https://nutritionfacts.org/2022/05/17/blueberry-blocking-effects-of-yogurt/
