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Milk myths: eight common concerns about cow’s milk debunked

Is cow's milk really bad for you? We reveal the facts behind common beliefs about the white stuff

Milk myths: eight common concerns about cow’s milk debunked

Cow’s milk has had some pretty poor press in recent years. Not only have dairy products come under fire for their sustainability credentials, but many people have also come to believe that milk is bad for your health.

But while dairy products can have a higher carbon footprint than some plant foods, some of the other accusations levelled at cow’s milk don’t stand up to scrutiny.

We asked two experts – Dr Simon Steenson, British Nutrition Foundation nutrition scientist; and Dr Phil Garnsworthy, University of Nottingham professor of dairy science – for the facts on some of the most common myths about cow’s milk.


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Myth 1: Humans aren’t designed to drink cow’s milk

Most people can easily digest milk, which humans have been drinking since they first domesticated animals around 10,500 years ago.

Lactose, the sugar that naturally occurs in milk, requires an enzyme to naturally digest it, but 5% of the UK population lack this enzyme due to their genetics and are lactose intolerant. 

Professor Garnsworthy says: ‘This gene, which appeared in Northern Europe thousands of years ago, allowed humans to drink more milk and get vitamin D, which compensated for lack of sunlight.’

However, the NHS says that in the UK, cows’ milk is generally not a good source of vitamin D because it is not fortified, as it is in some other countries.

‘The proportion of people with lactose intolerance is higher in Asian and African countries where liquid milk was not traditionally consumed,’ adds Professor Garnsworthy.

If you’re lactose intolerant, you might still be able to tolerate dairy products where lactose is removed (such as butter), digested (such as cheese) or fermented (such as yoghurt) – or lactose-free milk.

Myth 2: Cow’s milk makes you fat

Cows on a farm

Weight gain is about how many calories you consume compared with how many your body needs. This is down to diet and lifestyle as a whole, and is unlikely to be caused by any one food or drink.

Dr Steenson says: ‘Although people sometimes talk about ‘full fat’ milk, whole cow’s milk is about 4% fat, and most of us choose reduced-fat versions that are less than 2% fat.

‘So, milk in itself isn’t a high-fat food and, overall, the scientific evidence tends to show that drinking milk has a neutral effect on body weight.’

Myth 3: Cow’s milk can give you acne

Some people believe that drinking milk can give you acne but there is insufficient evidence that this is the case.

Dairy foods have been blamed for causing or worsening several conditions, including acne and rosacea.

Dr Steenson says: ‘While there is some evidence to suggest that consuming milk may trigger acne in some people, this has not been studied in detail. We don’t have proof of a clear link between dairy and acne, nor that dairy triggers skin problems in most people.’

A systematic review concluded that the few surveys that reported increased acne with milk drinking didn’t take other factors into account, were based on recall rather than measuring food intake, or had non-medical definitions of acne.

Myth 4: Cow’s milk is full of hormones 

Myths abound about cow’s milk being pumped full of hormones, and cows being milked when they have conditions such as mastitis, but our experts say this simply isn’t true.

Professor Garnsworthy says: ‘Milk contains trace amounts of naturally occurring steroid hormones such as oestrogens, but intakes are small compared with what people produce themselves.’ 

The main concern about hormones is from stories about injecting cows with growth hormone – bovine somatotropin, or BST – to increase milk production. 

Although there is no evidence of a health risk, this practice was banned in Europe in 1999 on animal health and welfare grounds.

Myth 5: Cow’s milk contains pus

Critics of drinking cows' milk claim that it is full of undesirable things including antibiotics and pus but experts say this isn't true.

Pus is composed primarily of white blood cells and conjures up visions of infected wounds.

However, Dr Steenson says: ‘In relation to milk containing ‘pus’, this isn’t accurate and this misconception comes from the fact that all milk naturally contains some white blood cells that are part of the immune system.’

White blood cells are present in the milk of healthy cows and provide gut immunity against dangerous pathogenic bacteria.

‘Levels of white blood cells in milk are monitored and have to be kept low, as this indicates that cows are healthy,’ adds Dr Steenson.

Myth 6: Cow’s milk is full of antibiotics

Some people claim that milk is full of antibiotics and that when we drink milk we ingest those antibiotics, too.

Professor Garnsworthy says: ‘This is completely untrue. Antibiotics are used to treat sick cows, but milk is withheld from sale until antibiotics have cleared the cow’s system.’ 

Every single load of milk collected from a dairy farm is tested for antibiotics. If even trace amounts are detected, the whole tanker full of milk is rejected and the farmer is fined thousands of pounds.

Myth 7: Plant ‘milks’ are better for you

Plant alternatives to milk - such as rice, soya and almond 'milks' - have seen a massive rise in popularity.

Plant-based milk alternatives have seen a massive rise in popularity, with consumption growing by more than 20% in a year. But are they a good alternative to cow’s milk when it comes to your health?

Professor Garnsworthy says: ‘Milk protein is actually higher quality than plant proteins because it has the right balance of amino acids and is digested more readily.’

Cow’s milk contains a range of nutrients essential for human health, including calcium, phosphorus and vitamins B12 and B2. It is also an important source of iodine – dairy products provide around a third of the iodine needs of UK adults and more than a half of the needs of younger children.

However, plant-based versions, unless fortified, don’t always have these nutrients.

Dr Steenson says: ‘Iodine is essential for healthy growth and development in children, but not all plant-based milk alternatives are fortified with iodine at the moment. For people who want or need to choose plant-based milk alternatives, it is a good idea to make sure you opt for one fortified with calcium and ideally other vitamins and minerals.’

Myth 8: Cow’s milk is full of sugar

It has been suggested that milk can contribute to type 2 diabetes because it contains sugar.

While milk does contain a small amount of sugar naturally in the form of lactose, this doesn’t count towards your daily intake of what is known as ‘free sugars’.

Free sugars are those we should be aiming to eat less of, such as sugars added to foods or drinks or those found in honey or fruit juice.

Dr Steenson says: ‘The evidence doesn’t suggest that milk and other low-fat dairy products increase the risk of obesity or diabetes, but instead that it might actually help protect against the risk of developing type 2 diabetes over time.’ 

Professor Garnsworthy points out that milk contains about 4.7% sugar. ‘This puts it somewhere between tomatoes and sweet potatoes, but much lower than food with added sugar such as baked beans and ketchups.’


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Cow’s milk: the verdict

Cow’s milk can be an useful source of calcium, protein, vitamins and minerals, and concerns about it being full of hormones and antibiotics here in the UK are unfounded.

The use of hormones to increase milk yields is illegal in the UK and EU, and antibiotics are only allowed to be given to cows to treat disease.

Milk is tested for traces of antibiotics before it reaches us to ensure it’s safe for consumption.

If you’re considering plant-based alternatives, look for options that are fortified, and make sure you check the sugar levels. See our full guide to plant-based milks for more.

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