Rethinking dairy

Dr Justine butler senior Researcher and Writer viva!health

dr Justine butler is a Senior researcher and writer at Viva!health. Justine holds a Phd in molecular biology, bSc biochemistry and diploma in nutrition. She has published an extensive list of reports, guides and factsheets for Viva!health and written articles for health journals, regional and national press.

We know about the health risks associated with fish contaminated with pollutants (1). The links between red and processed meats and bowel cancer are well-documented (2). However, dairy continues to slip under the net. It’s as if the white stuff is so pure, natural and wholesome its beneficial properties are beyond question. It is portrayed as liquid calcium for bones, an elixir of goodness for the young, the fussy, the poorly and the elderly. However, a large body of evidence links cows’ milk and dairy products to a wide range of illnesses and diseases including heart disease, diabetes and cancer, right through to acne, allergies and even osteoporosis, suggesting that cows’ milk could be doing more harm than good.

heaRt Disease The number of people in the UK with heart disease has remained relatively constant over the last decade. The benefits we should be seeing (due to advances in medical treatment and the reduction in smoking) are being negated by the increase in obesity and diabetes. We are smoking less, but we are eating more, and not just that, we are making poor dietary choices. Heart disease is linked to poor diets including high levels of saturated fat, salt and refined carbohydrate and low levels of fruit and vegetables (3). Foods high in saturated fat include: meat pies, sausages and fatty cuts of meat, butter, ghee, lard, cream, hard cheese, cakes and biscuits and foods containing coconut or palm oil (4). Interestingly replacing saturated fat with polyunsaturated fat may be more effective in lowering the risk of heart disease than reducing the total amount of fat in the diet. This means moving away from saturated animal fats to unsaturated vegetable oil-based fats. A move that offers major health benefits according to the World Health Organisation (5). So go dairy-free, while increasing the intake of fibre, fruit and vegetables is a simple way of reducing saturated fat intake, losing weight and lowering the risk of diabetes and heart disease.

Soya protein, nuts, plant sterols and soluble fibres from wholegrain foods, fruit and vegetables can all help lower cholesterol which is a risk factor for heart disease (6). Vegetarians (who eat a diet based on cereals, pulses, nuts, fruits and vegetables) tend to have lower cholesterol levels and a lower mortality from heart disease. The widespread adoption of a vegetarian diet could prevent approximately 40,000 deaths from heart disease in Britain each year (7). This means a healthy plant-based vegetarian diet and not one based on cream cakes and cheesy pizzas.

Diabetes Over the last 60 years, the worldwide incidence of Type 1 diabetes has risen by over three percent a year, doubling every 20 years, with a rapid rise in the number of children affected (8). In 2035, the NHS could be spending 17 percent of its entire budget on treating diabetes (9).

Type 1 diabetes is an autoimmune condition whereby the immune system attacks the body’s own insulin-producing cells in the pancreas. It is thought to involve a genetic predisposition (diabetes in the family) coupled to an environmental trigger. Putative triggers include: viral infection, vaccines, low levels of vitamin D, increased insulin demand and the early exposure to cows’ milk protein. It is only in recent years that cows’ milk protein has been identified as a potential trigger for Type 1 diabetes (10, 11). Candidate milk proteins in milk include casein (12), bovine serum albumin (13) and bovine insulin (14). Even a short duration and/or a lack of breastfeeding may constitute a risk factor for Type 1 diabetes (15).

The World Health Organisation recommends that infants should be exclusively breastfed for the first six months of life. Yet the government continues to scrap funding for infant feeding coordinators (who encourage breastfeeding in parts of the country with the lowest uptake) and withdrew funding of the National Breastfeeding Awareness Week in 2011. Last year, figures from the Department of Health revealed that the number of new mothers who are breastfeeding fell for the first time since they began collecting statistics in 2004. From 2012-2013, nearly half of all new mums were not breastfeeding their baby at all by their eight week check-up (16). The Royal College of Midwives have expressed concern over the lack of promotion of breastfeeding under the current Government, saying there is a shortage of 5,000 midwives. Strategies to promote breastfeeding could confer important and widespread health benefits and not just with respect to Type 1 diabetes.

Type 2 diabetes (normally affecting adults over 40) is occurring in young adults at the level of a global epidemic driven by the increasing burden of obesity (17, 18). The risk factors for Type 2 diabetes (obesity, poor diet and lack of exercise) are well-documented and one obvious preventative measure is to reduce the amount of saturated fat in the diet. This means cutting down on meat and dairy and increasing the intake of fruit, vegetables, wholegrains, pulses, nuts and seeds. Vegetarian and vegan diets offer significant benefits for diabetes management, including weight loss and improving blood lipid profile and glycaemic control (19, 20). Increasing dietary fibre can help and should be encouraged as a disease management strategy (21, 19, 22).

CoWs’ milK anD CanCeRs Selective breeding and modern intensive farming practices have significantly changed the nature of cows’ milk. Modern dairy cows are routinely impregnated while still producing milk (23), so over two-thirds of UK milk is taken from pregnant cows, the rest coming from cows that have recently given birth (24). As a consequence, commercial milk products contain considerable levels of hormones (25) which may be linked to the development of some hormone-dependent cancers. Furthermore, cows’ milk stimulates the production the growth hormone IGF-1 in the liver and so drives up circulating levels of this hormone. IGF-1 has been shown to stimulate the growth of human cancer cells in the laboratory (26) and increased levels are linked to cancers of the bowel, breast and prostate. Professor T Colin Campbell, Jacob Gould Schurman Professor Emeritus of Nutritional Biochemistry at Cornell

University, New York, says that IGF-1 may turn out to be a predictor of some cancers in the same way that cholesterol is a predictor of heart disease (27). While dairy increases IGF-1, avoiding milk and dairy products can reduce the level of circulating IGF-1. A study published in the British Journal of Cancer found that vegan men had a nine percent lower IGF-1 level than meateaters and vegetarians (28). The significance of this needs to be further investigated, but it seems reasonable to assume that going dairy-free may lower the risk of certain cancers.

boWel CanCeR Some reports suggest that dairy products may very slightly lower the risk of bowel cancer (29). However, this effect may be attributable to vitamin D (30) and/or calcium (31) which can be obtained from plant-based sources. Furthermore, dietary calcium increases the risk of prostate cancer (32), so recommending dairy to men to lower their risk of bowel cancer would not be advisable. As stated, milk increases IGF-1 in the blood and higher IGF-1 levels are linked to an increased risk of bowel cancer (33, 34, 35). On a positive note, it is well-documented that increasing the intake of fruit and vegetables can significantly lower the risk of bowel cancer (36, 37).

bReast CanCeR Female breast cancer incidence rates in Britain have increased by almost 70 percent since the mid-1970s. Just in the last 10 years they have increased by six percent. The lifetime risk for women in the UK is now one in eight. Only five to 10 percent of all breast cancers are caused by genes (38), the vast majority are caused by environmental factors. Research from Harvard School of Public Health suggests that nearly a third of all breast cancer deaths in high-income countries are caused by preventable lifestyle factors: alcohol, overweight/obesity and lack of exercise (39). Indeed, the global rise in breast cancer is often attributed to the adoption of a more Western-style lifestyle. A significant number of breast cancers could be prevented by changing the diet (40). Dietary modification may also affect progression of the disease in those who already have breast cancer (41).

Women with breast cancer tend to have higher levels of oestrogens in their blood (42, 43, 44). A typical Western-style diet, rich in meat and dairy, increases the levels of these hormones (45, 46). Saturated fat intake has been implicated and, as stated, dairy products are a major source. Researchers at the Department of Preventive Medicine at the University of Southern California Medical School in Los Angeles published a review of 13 studies that investigated the effect of fat intake on oestrogen levels. Results showed that decreasing dietary fat intake (to just 10 to 25 percent of the total energy intake) reduced circulating levels of oestrogen by as much as 10 percent. They suggest that reducing fat intake to lower hormone levels may help prevent breast cancer (47).

However, low-fat dairy products may not be the answer. Numerous studies have focused on the hormone content of milk. Cows’ milk contains hormones and increases the level of IGF-1 in the blood (by increasing endogenous production from the liver). Increased IGF-1 levels are linked to cancers of the bowel, prostate and breast. Author of the book Your Life in Your Hands, Professor Jane Plant, from Imperial College London, is so convinced that the low-fat yoghurt and skimmed organic milk she was eating was responsible for her breast cancer that she now advocates the complete avoidance of all dairy products. Her cancer

specialist agrees and recommends a dairy-free diet to his cancer patients.

On the other hand, high-fibre, low-fat diets may offer some protection against breast cancer (46, 48) possibly by lowering hormone levels (49, 47). Soya foods may also reduce breast cancer risk (50) and improve the prognosis in women with breast cancer (51). In summary, a dairy-free plant-based diet can reduce the risk factors associated with breast cancer and may help those who have been diagnosed with the disease.

pRostate CanCeR The lifetime risk of prostate cancer for men in the UK is about one in nine (52). Just five to 15 percent of prostate cancers are linked to genes (53). So, like breast cancer, the majority of cases are caused by environmental and/or lifestyle factors. We know that obesity and lack of exercise increases the risk, but less is known about the effect of diet. Prostate cancer rates are higher in countries consuming a typical Western diet. Men who eat a lot of saturated animal fats (including red meat such as beef, lamb and pork, eggs and dairy produce such as butter, whole milk, cheese and cream) have an increased risk of getting the disease (53). Diets high in calcium and dairy protein may also increase the risk of prostate cancer (54, 55, 56). It has also been suggested that regular exposure to oestrogen in milk from pregnant cows may explain the increased risk of prostate cancer in Western societies (57).

iGf-1 siGnallinG tRouble As stated, dairy products increase circulating IGF-1 levels (58, 59) and higher IGF-1 levels are associated with an increased risk for prostate cancer (60, 61, 62, 63). Furthermore, IGF-1 may transform pre-existing or benign tumours into a more aggressive form of cancer (64, 65). So, IGF-1 from cows’ milk may be a risk factor that could easily be avoided by eliminating dairy foods from the diet. Whether it is the saturated animal fat, the calcium, the hormones in milk or the hormones we produce in response to drinking milk, the fact remains that a high dairy diet appears to increase the risk of prostate cancer. On the positive side, a plant-based diet may slow prostate cancer progression and improve prognosis (66, 67, 68). In addition, specific plant foods, including flaxseeds (linseed) and lycopene-rich tomatoes (64) and soya foods (69), may help reduce the risk, along with a high level of physical activity (70).

summaRy In summary, the research linking the consumption of cows’ milk and dairy products to numerous different types of cancer provides a convincing argument for eliminating all dairy from the diet, while increasing the intake of wholegrains, pulses (including soya), fruit and vegetables. The realisation is growing that changing our diet can have an enormous impact on health - for better or for worse. But what constitutes healthy or unhealthy food is not universally agreed and seems to change on a weekly basis. Cows’ milk is vigorously defended by the dairy industry, but the evidence paints a very different picture. If the huge numbers of people suffering from heart disease, diabetes and cancer could be reduced by one simple change in the diet, wouldn’t it be worth trying? This article presents a summary of an extensive fully-referenced scientific report called White Lies. All the facts presented are based on peerreviewed published research. To find out more, or to access the full references, visit: www.whitelies. org.uk/resources/white-lies-report-2014