Should you ditch the dairy from your diet?

Milk’s reputation is no longer whiter than white. Popular ‘wellness’ writers advocate avoiding milk to combat a range of health problems, while Dr Mark Hyman, a New York Times bestselling author, goes so far as to claim that adults are incapable of digesting dairy. “Dairy is nature’s perfect food – but only if you’re a calf,” he states on his website.

No surprise, then, that increasing numbers of people are taking milk, cheese, yogurt and butter off the menu. Meanwhile, sales of plant-based ‘mylks’ – the EU bans the use of the term ‘milk’ on drinks from non-animal sources – are booming. According to market research firm Mintel, non-dairy milk sales in the UK soared by 30 per cent between 2015 and 2017, with almond milk most popular.

The science bit

Milk contains a form of sugar called lactose, which can’t be absorbed and used by the body as it is; it needs to be broken down by an enzyme in the intestine called lactase. When we’re babies, we produce lactase to absorb our mother’s milk. In most mammals, lactase levels decline after weaning because they generally never encounter lactose again. This has prompted people like Dr Hyman to suggest that adults are not biologically wired to drink milk.

Dietitians disagree. “Humans have had dairy in their diet for thousands of years,” says Sophie Medlin, dietitian and lecturer in nutrition and dietetics at King’s College London. “Without milk, it is unlikely that humans would have survived in northern Europe at all. Most people are able to digest milk well because we have adapted to be able to do so.”

It’s true that some people can’t handle dairy and suffer from bloating, abdominal pain and wind, caused by gas from unabsorbed lactose which ferments in the gut. People with a cow’s milk allergy need to be particularly careful to avoid dairy as an allergic reaction occurs when their immune system incorrectly identifies the milk protein as dangerous, triggering symptoms ranging from diarrhoea to life-threatening anaphylaxis.

The British Nutrition Foundation estimates only 5 per cent of people in northern European countries, such as the UK, have a genuine problem with digesting lactose, but the intolerance is more common in other European countries and in Afro-Caribbean and Asian communities. Surprisingly, many people with a genuine lactose intolerance are able to drink 200ml cow’s milk with a meal without suffering symptoms.

Fermented products such as natural yogurt can be easier to digest, and hard, aged cheeses, such as cheddar, gruyère and parmesan, contain little or no lactose because it’s removed during the cheese-making process.

Increasing numbers of people are giving up dairy simply because they believe it’s healthy to do so. But is it?

The benefits of dairy

“It’s not a good idea to exclude dairy from your diet unless it’s due to allergy or intolerance,” says Professor Ian Givens, director of the Institute for Food, Nutrition and Health at the University of Reading. “Dairy foods (except butter, which is mostly fat and water) are important sources of key nutrients including high-quality protein, calcium, iodine and several B vitamins.”

Milk naysayers point out these nutrients are widely available in other foods, but dieticians and scientists say that, of all the sources, the body is best able to absorb the calcium in dairy.

Bones store calcium and other minerals for use throughout our lives. Failing to build strong bones can lead, in later life, to osteoporosis, a disease in which bones become brittle and fragile. “Dairy foods have the perfect matrix of nutrients to build bones,” says Sophie Medlin. “Our bones get stronger until we’re around 30 and after that bone density usually starts to deteriorate. That’s why investing in bone health in childhood is essential.”

Girls aged 11-18 are also at risk of iodine deficiency because they don’t drink enough milk, adds Prof Givens. Iodine is essential for the body to make the thyroid hormone, which is important for women of child-bearing age. “The first three months of pregnancy are critical for iodine status as the foetal thyroid isn’t functional,” Prof Givens says.

New findings

Recent studies suggest that eating dairy may also have broader health benefits. Prof Givens says the proteins in cow’s milk are now associated with a “small but valuable” reduced risk of stroke. “Research also shows that eating fermented dairy, especially yogurt, is associated with a substantial reduction in the risk of type 2 diabetes, although the mechanisms for this are not fully understood.” In its latest report, the World Cancer Research Fund concludes that consumption of dairy probably protects against colorectal cancer.

Dairy’s combination of calcium, protein and fat is linked to lower cholesterol and a healthy heart, particularly when eaten as cheese.

The bottom line

Unless you have an intolerance or allergy, there are no health benefits to excluding dairy from your diet: indeed the opposite might be true. Dairy is highly nutritious and a valuable source of calcium and iodine. Evidence also suggests that eating dairy can reduce the risk of stroke and some forms of cancer.