How & Why Is Dairy Linked to Disease?

Dairy consumption has been linked to many health issues ranging from acne and asthma to certain cancers and diabetes.

Here we explain why dairy is the culprit in many of these diseases. Click on each health condition below to read how and why it's linked to milk and dairy products or for detailed and referenced information, scroll down to the White Lies report.

Acne is much less common in non-Western societies and increases with junk food diets. It is caused by obstruction and inflammation of hair follicles and the oil (sebum) glands in the skin. If hair follicles become infected with bacteria (usually Propionibacterium acnes) the situation gets worse.

Several large studies discovered that the more dairy products teenagers consumed, the more they suffered from acne. The most likely cause, say the authors, is the many hormones and other bioactive molecules that dairy products naturally contain.

One of the main culprits is a growth hormone called IGF-1 (insulin-like growth factor 1), which is what calves need to grow fast. Dairy products contain it but they also increase production of your body’s own IGF-1. On top of that, there are steroid hormones in dairy which directly affect your skin cells. They encourage more and faster production of oil (sebum) and skin cells and the result is oily skin and clogged pores where bacteria can breed.

Body builders who use steroid hormones are more prone to acne and so are athletes who use whey-based shakes, supplements and the like. Dairy affects hormone levels and therefore the skin. Case studies show that young athletes lost their acne when taken off whey supplements but it returned when they went back to using whey.

Rheumatoid arthritis is a chronic inflammatory disease of the joints causing considerable pain and discomfort. Rheumatoid arthritis is thought to be an autoimmune disease, where the immune system that makes the body to attack its own tissues.

It has been suggested that dairy may trigger an autoimmune response in some people who may then go on to develop rheumatoid arthritis via a mechanism called molecular mimicry. This may occur when the immune system reacts to a protein in cow’s milk called bovine serum albumin and produces antibodies to attack it but because one of the joint cartilage proteins – collagen – has a similar structure, the antibodies attack it too.

Another link between dairy and rheumatoid arthritis is through a strain of bacteria commonly found in milk and beef (Mycobacterium avium subspecies paratuberculosis, shortened to MAP) which may trigger the development of rheumatoid arthritis in people who are genetically at risk. You can get infected by the bacteria by consuming milk or beef that contains it.

Asthma is a chronic, inflammatory lung disease characterised by recurrent breathing problems. During an asthma attack, the lining of the airways becomes inflamed and the airways become narrower causing the characteristic symptoms of asthma: coughing, wheezing, difficulty in breathing and tightness across the chest.

Food allergy is often associated with asthma and milk is one of the most common food allergens. However, even people who are not allergic to milk often find that dairy is either the trigger or makes their asthma worse - diets higher in fat, particularly saturated fat from dairy products and meat, have been directly linked to asthma. On the other hand, a diet based on plant foods and rich in fruit and vegetables can reduce the frequency and severity of attacks.

The links between dairy and cancer are much debated. However, for hormone sensitive cancers in particular – prostate, breast and ovarian – the scientific evidence keeps mounting. Regular dairy consumption ensures that you’re ingesting hormones (naturally present in dairy) including oestrogens, progesterone and growth hormones, and saturated fat. These milk components have been suggested to play a role in the development or growth of hormone sensitive cancers. For ovarian cancer, milk sugar (lactose) has also been repeatedly associated with an increased risk of the disease.

Two-thirds of milk in the UK is taken from pregnant cows with the remainder coming from cows that have recently given birth. This means the hormone content in milk is much higher than it used to be decades ago and before the start of industrial farming. Dairy consumption also increases the production of IGF-1 (insulin-like growth factor 1) in the human body and increased levels of this hormone have been linked to higher risks of cancer.

Colic is the medical term for excessive, frequent crying in a baby who appears to be otherwise healthy and well fed. It is a poorly understood yet common condition that affects around one in five babies. Typically, a baby with colic will scream and draw up their legs, and may refuse to be comforted.

Several factors are thought to contribute including poor digestion, lactose intolerance and/or a reaction to cow’s milk proteins. Certain components of cow’s milk may lead to colic - in a clinical trial to investigate the effects of cow’s milk whey proteins, 24 out of 27 infants with colic showed no symptoms of colic after whey protein was removed from their diet. In order to alleviate the negative effects of cow’s milk whey proteins (and other milk proteins thought to cause colic) some infant formulas are hydrolysed, this means the proteins are broken up. These hydrolysed formulas are called hypoallergenic and have been shown to be effective in the treatment of colic in some infants.

Many reports now also link the maternal intake of cow’s milk to the occurrence of colic in exclusively breastfed infants. The breast milk of mothers who consume cow’s milk and milk products has been shown to contain intact proteins from these foods. In trials where mothers eliminated all dairy products from their diet, the colic disappeared in over a half of the infants.

In children, chronic constipation may be a symptom of milk allergy or intolerance. In studies where dairy products were removed from children’s diets, most of them experienced relief.

In adults, dairy can also cause constipation – it’s been suggested that one type of protein found in milk, A1 beta-casein, slows down the speed at which food moves through the digestive tract which can contribute to constipation.

Dairy products contain no fibre – a natural component of plant foods essential to a healthy digestive tract and bowel movements – so a diet based on dairy and other animal products can be severely lacking in fibre and thus causing constipation.

Crohn’s disease is a chronic inflammatory bowel disease (IBD). It is a long-term condition that causes inflammation of the lining of the digestive system. The symptoms are similar to other bowel conditions such as irritable bowel syndrome (IBS) and ulcerative colitis and can include diarrhoea, abdominal pain, fatigue (extreme tiredness), unintended weight loss and blood and mucus in the faeces.

Crohn’s is linked to dairy foods through a bacterium cattle often carry. The MAP bacterium that causes Johne’s disease in cattle is also found in retail pasteurised cow’s milk and in rivers contaminated with infected cow manure. A substantial body of evidence now supports the causal link between MAP and Crohn’s disease in people. Professor John Hermon-Taylor at St George’s Hospital Medical School in London has found MAP in patients with Crohn’s disease from the UK, Ireland, US, Germany and United Arab Emirates.

Over the last 60 years, the worldwide incidence of type 1 diabetes has risen by over three per cent a year, doubling every 20 years, with a rapid rise in the number of children affected. If this trend continues in 2035 the NHS could be spending 17 per cent of its entire budget on treating diabetes.

Early exposure to cow’s milk proteins has been linked to type 1 diabetes, where little or no insulin is produced. Candidate proteins include: casein, bovine serum albumin and bovine insulin. Unfortunately, these proteins ‘look like’ our own pancreatic cells and may trigger an inappropriate immune response in genetically susceptible people whereby our own immune cells set about destroying these foreign dairy proteins and our pancreatic cells. This autoimmune reaction leads to diabetes. Even a short duration of exposure to cow’s milk infant formula may constitute a risk factor for type 1 diabetes.

Type 2 diabetes (normally affects adults over 40) is occurring in young adults at the level of a global epidemic driven by the increasing burden of obesity. 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 out meat and dairy and increasing the intake of fruit, vegetables, whole grains, pulses, nuts and seeds. Indeed, low-fat vegan diets have been shown to reverse type 2 diabetes.

Gallstones are solid pieces of stone-like material, usually made of cholesterol, that form in the gall bladder, which is a small organ on the right side of the body, below the liver. It stores a green liquid called bile, which is produced by the liver to help the body digest fats. As we eat, bile is released from the gall bladder into the intestines through a thin tube called the bile duct. Gallstones are formed when some of the compounds stored in the gall bladder harden into a solid mass – they are made up of cholesterol and other fats, bile salts and the pigment bilirubin. They may be as small as a grain of sand or as large as a golf ball. Some people may have one large stone while others may have many small ones. Gallstones are the most common cause of emergency hospital admission for people with abdominal pain - the passage of a gallstone along the bile duct to the small intestine can be extremely painful.

The main dietary risk factors appear to be low fibre (plant foods) intake, high saturated fat and cholesterol intake (animal fats) and obesity. High-fat dairy products (butter, cheese, cream, ice cream) are among the main sources of saturated fat and cholesterol in Western diets.

Diseases of the heart and circulatory system are collectively called cardiovascular disease (CVD) and are a leading cause of death in the UK. Coronary heart disease (CHD) is one of the two main forms of CVD along with stroke. CHD occurs when there is a build-up of fatty deposits (plaques) along the walls of the arteries that supply the heart with blood. These plaques build up and clog the arteries making them narrower and restricting the blood flow. Blood clots can form at the site of a plaque in the coronary artery and cut off the blood supply to the heart. This can result in heart attack and sudden death. The scenario for stroke is similar but occurs in the brain - if the supply of blood is restricted or stopped, a stroke may occur and brain cells could begin to die, which can lead to brain damage and possibly death.

The plaques that block the arteries are made up of a fatty substance that contains cholesterol and diets high in saturated fats increase the risk of these plaques forming. Foods high in saturated fat include a number of dairy products: butter, ghee, lard, cream, hard cheese, dairy ice cream, whole milk and cakes. Replacing unhealthy saturated fat with healthier polyunsaturated fats from plant foods may actually be more effective in lowering the risk of heart disease than reducing the total amount of fat in the diet. Soya (protein), nuts, plant sterols and soluble fibres (found in oats and some fruit, vegetables and pulses) all help lower cholesterol which is a risk factor for heart disease.

Milk naturally contains hormones – they are there to help direct the growth of the calf and include growth hormones (eg IGF-1), oestrogens, progesterone, adrenal and pituitary hormones. There are 35 different hormones present in cow’s milk – all cow’s milk, without exception. However, as milk is taken from pregnant cows and cows that have recently given birth, it contains even higher levels of certain hormones and these have been linked to some hormone-sensitive cancers, such as breast, prostate and ovarian cancer.

In addition to that, cow’s milk stimulates your own body to produce the growth hormone IGF-1 in the liver. IGF-1 stimulates the growth of human cancer cells in the laboratory and increased IGF-1 levels are linked to cancers of the bowel, breast and prostate. Professor T. Colin Campbell, Professor Emeritus of Nutritional Biochemistry at Cornell University, says that IGF-1 may turn out to be a predictor of certain cancers in the same way that cholesterol is a predictor of heart disease. Furthermore, IGF-1 may transform pre-existing or benign tumours into a more aggressive form of cancer.

In 1836, after returning from the Beagle, Charles Darwin wrote “I have had a bad spell. Vomiting every day for eleven days, and some days after every meal.” Darwin suffered for over 40 years from long bouts of vomiting, stomach cramps, headaches, severe tiredness, skin problems and depression. A number of researchers now suggest that he suffered from lactose intolerance. His case is a good example of how easily lactose intolerance can be missed.

We are only meant to consume breastmilk in infancy and then stop which is why the human body produces the enzyme to digest lactose (the sugar in both breastmilk and cow’s milk) in the early years of life and, in most people, gradually stops producing in during childhood. The ability to digest lactose in adulthood evolved as a result of a genetic mutation among some people in central Europe around 7,500 years ago (and a couple of other places). Descendants of these people are able to consume dairy milk today without suffering the symptoms of lactose intolerance (bloating, wind, discomfort etc). However, that doesn’t mean it is good for them. Being lactose intolerant is the natural, normal state for most adults in the world.

Allergy vs intolerance: Lactose intolerance should not be confused with cow's milk allergy, they are entirely different. Cow's milk allergy is where the immune system reacts to cow's milk proteins. Lactose intolerance is where the body cannot digest lactose – the sugar in milk.

A migraine is much more than a bad headache; unless you suffer from them it is difficult to appreciate just how debilitating a migraine can be. Often people with a migraine can do nothing but lie quietly in a darkened room waiting for the pain to pass. The pain is excruciating, often accompanied by nausea, vomiting and an increased sensitivity to light and sound. A migraine can last for a few hours or a few days.

A range of common factors that can cause migraines in some people have been identified. Some scientists suggest that fluctuating levels of hormones may be linked to the causes of migraines (hence the higher number of women affected). Other factors include: emotional, physical, environmental, medicinal and dietary factors. Foods are frequently identified as triggers and the most common culprits include dairy products (particularly cheese), chocolate, alcohol (particularly red wine), caffeine, citrus fruits, nuts, fried foods and foods containing monosodium glutamate (MSG) such as some Chinese food, processed meats and frozen pizzas. Other triggers include cigarette smoke, bright lights, hunger, certain drugs (such as sleeping tablets, HRT and the combined oral contraceptive pill), loud noises, strong smells, neck and back pain, stress and tiredness. All these factors and others can lead to a migraine, and some people may experience a migraine following any one or a combination of these factors.

The national medical charity Allergy UK lists cheese (particularly Stilton, Brie, Camembert and Emmenthal) as the third commonest cause of food-induced migraine after alcohol and chocolate.

Multiple sclerosis (MS) is the most common disease of the central nervous system (the brain and spinal cord) affecting young adults in the UK. It is estimated that there are currently around 100,000 people with MS in the UK. Symptoms usually first develop between the ages of 15 and 45, with the average age of diagnosis being about 30.

Sclerosis means scarring and multiple refers to the different sites at which the scarring can occur throughout the brain and spinal cord. In MS the protective sheath (myelin) that surrounds the nerve fibres of the central nervous system becomes damaged. When myelin is damaged (demyelination) the messages between the brain and other parts of the body become disrupted.

MS is an autoimmune disease whereby the body’s immune system attacks its own tissues. As with other autoimmune diseases, it is thought that a combination of genetic factors and environmental triggers cause the disease. Recent research shows that an important environmental factor is diet.

Several studies found a link between the consumption of cow’s milk and the incidence of MS. Other research suggests that for people who already have MS, avoiding saturated fats (dairy and meat) may significantly slow down the progression of the disease.

Most people know what the term obesity means: an increased body weight caused by the excessive accumulation of fat. Overweight and obesity occur when more calories are taken into the body than are burnt up over time. In other words, if you don’t burn up the energy you consume it will be stored as fat, and over time this may lead to excessive weight gain and obesity.

Abdominal fat (also known as internal or visceral fat) is of particular concern because it’s a key player in a variety of health problems including high blood pressure and cholesterol (which can lead to heart disease), diabetes and some cancers. You don’t have to be overweight or obese to have high levels of this type of fat. Some slim people, who do little or no exercise, can have elevated levels of visceral fat. Unlike subcutaneous fat (the kind you can grasp with your hand), visceral fat lies deep within the abdominal region, hidden in the white fat that surrounds the vital organs, streaked through underused muscles and wrapped around the heart.

The main causes of obesity include an excessive intake of food coupled to a lack of exercise and a sedentary lifestyle. As populations become more urban and incomes rise, diets high in sugar, fat and animal products replace more traditional diets that were high in plant foods with healthy carbohydrates and fibre.

Cutting the amount of fatty and sugary foods in the diet, replacing them with plant-based wholefoods and moving from saturated animal-based fats to unsaturated plant fats is a smart move towards a healthy weight. Whole milk, cheese, cream, butter, ice-cream and most other dairy products, apart from skimmed and non-fat products, contain significant amounts of saturated fat and cholesterol. There is no nutritional requirement for saturated fat in the human diet so cutting dairy foods out is a healthy decision.

Osteoporosis (meaning porous bones) is a condition that affects the bones, causing them to become weak and more likely to fracture. Although the whole skeleton is usually affected, fractures most commonly occur in the spine, wrist and hips. Osteoporosis develops when calcium is lost from the bones and they become more fragile. It’s commonly associated with post-menopausal women but osteoporosis can also affect men, younger women and children. In the UK, one in two women and one in five men over the age of 50 will break a bone mainly because of poor bone health.

Many people believe that because dairy contains calcium, it must be good for the bones – which is a testament to the dairy industry’s marketing but bears no relevance to reality. In countries with the highest milk and dairy products intake, the rates of osteoporosis are also the highest.

In their recommendations for preventing osteoporosis the World Health Organisation state that:

The paradox (that hip fracture rates are higher in developed countries where calcium intake is higher than in developing countries where calcium intake is lower) clearly calls for an explanation. To date, the accumulated data indicate that the adverse effect of protein, in particular animal (but not vegetable) protein, might outweigh the positive effect of calcium intake on calcium balance.”

Western style diets (rich in dairy foods and animal protein) accompany hip fracture rates around the world. We do need calcium for healthy bones but as research shows, we’re best off getting it from plant sources as dairy products don’t help to improve our bone health and animal protein (from meat, dairy and eggs) may even weaken the bones because it increases calcium losses.

What matters most when it comes to bone health is physical (especially weight-bearing) activity to stimulate bones and a healthy diet and lifestyle - this means eating plenty of fresh fruit and vegetables, pulses, wholegrains, nuts and seeds and cutting down on caffeine and avoiding alcohol and smoking.

FAQs — Health & Nutrition

What are the best calcium sources? What's important for bone health? And are there hormones in milk?

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