Dairy Dairy Quite Contrary

When it comes to breast cancer, evidence is mixed on whether consumption of dairy increases or decreases risk of breast cancer but, as is often the case, the devil’s in the details. 

In this case, it appears that higher milk consumption (>500mls per day) may increase your risk of post-menopausal hormone positive breast cancer. On the flip side, other evidence suggests lower fat or fermented dairy may be protective in populations at risk of premenopausal cancer.

Hopefully it goes without saying that a blog is not medical advice, but have a think about your individual and family medical history and how this relates to the above evidence and if this sparks some concern, please have a chat to your health care provider!

Although, once again, the evidence appears mixed, there is a slight lean toward dairy potentially increasing your risk of prostate cancer. This increase seems to be specifically linked to milk, and may be to do with milk’s potential to increase your blood levels of IGF-1. Elevated levels of IGF-1 have been linked to an increased risk of prostate cancer BUT, as always, potential benefits and risks need to be put into context. Personal medical history and family history of prostate cancer should both be considered when thinking about how dairy fits into your life. 

Ok, I think we’re safely out of the “evidence is mixed” part of the blog. 

Dairy is not inflammatory. There’s no evidence to back up that claim. In fact, there’s actually a bit of evidence suggesting dairy is ANTI-inflammatory. Oh the irony. 

To properly understand dairy’s impact on cardiovascular disease, we need to remember that dairy is a broad food group. Milk, butter, cream, cheese, yoghurt, ice cream and kefir are all technically dairy, but have very different nutrient profiles. 

Because of this, we can find evidence suggesting dairy increases your risk of heart disease, as well as plenty of evidence to suggest it doesn’t. Great.

Calcium seems to decrease the absorption of fat suggesting that you may not be absorbing all the fat within the dairy you’re consuming, it travels all the way through your body and out. This would reduce the impact of saturated fat on your body if it is not being absorbed but excreted. Another possible explanation is something that has strong literature to support is the milk fat globule membrane. If you picture an inflated balloon, all the saturated fat molecules in a dairy product start within the balloon. If you take a less processed dairy product, the idea is that this membrane remains intact and the saturated fat stays within the balloon/membrane and travels through you without being absorbed. In products that are more processed/churned (e.g. butter, ice cream) the membrane is broken and the saturated fat spills out into the food during processing so when we consume it, we’re absorbing all the saturated fat.

If you like nerding out (real word by the way) C-reactive protein (CRP), tumour necrosis factor alpha (TNF-a) interleukin-6 (IL-6) are all blood markers of chronic types of systemic inflammation and evidence pointed toward these markers being reduced by dairy. One potential reason for dairy copping such a bad wrap with inflammation is because of lots of dairy products are high in saturated fat. Saturated fat is associated with inflammation and an increased risk of cardiovascular disease (CVD). CVD by the way, includes things like coronary heart disease, heart attacks and strokes. So dairy products can have high levels of saturated fat, which is bad, but dairy isn’t bad…but again we look to the context of the situation, dairy is a broad term for different products that have differing levels of saturated fats and therefore differing levels of proposed protective benefits.

The term dairy includes butter, cream, milk, cheese, yogurt, ice cream and so on. It’s important to categorise those foods to then be able to specify whether each type of dairy food would have a positive or negative impact on cardiovascular health. When looking at dairy as a broad category of foods, the evidence falls into dairy having more positive and neutral impacts with little showing any real negative effects with low fat dairy cheese and fermented dairy seem to have the most positive impact on decreasing risk of coronary heart disease or stroke.

If heart disease or stroke is in your family medical history then, I would be considering low fat dairies, cheeses, yoghurt and kefir as these appear to slightly reduce your risk of cardiovascular disease.

Milk and other full fat dairy appear to have neutral impacts where the outcomes aren’t positive or negative. (Assuming we all know what neutral means but at the same time explaining it just in case). I touched before on the confusion around dairy not being bad for you but also saturated fat (which is in dairy) and there being a ton of evidence showing positive correlations with saturated fat and risk of heart disease. BUT, caveat, when you look at types of dairy there are 2 potential explanations for the different impacts with the first being the calcium content. Calcium seems to decrease the absorption of fat suggesting that you may not be absorbing all the fat within the dairy you’re consuming, it travels all the way through your body and out. This would reduce the impact of saturated fat on your body if it is not being absorbed but excreted. Another possible explanation is something that has strong literature to support is the milk fat globule membrane. If you picture an inflated balloon, all the saturated fat molecules in a dairy product start within the balloon. If you take a less processed dairy product, the idea is that this membrane remains intact and the saturated fat stays within the balloon/membrane and travels through you without being absorbed. In products that are more processed/churned (e.g. butter, ice cream) the membrane is broken and the saturated fat spills out into the food during processing so when we consume it, we’re absorbing all the saturated fat.

Earlier on I mentioned dairy as a category being more neutral and positive when it came to impacts on health where some specific dairy foods having a negative impact. This seems to be where the negative impact comes from and why something like butter is a higher risk dairy product for CVD.