Sugar is bad news for health — on this most would agree. However, fat has caused real controversy and often a tense debate.

For decades we have been warned that eating too much dairy such as milk, butter and cheese could raise our risk of serious conditions such as heart disease and strokes — only for more recent studies to suggest they might actually protect us from these by lowering our risk of developing high blood pressure or type 2 diabetes.

So where does the truth lie — and why can’t the scientists agree?

High levels of saturated fat are the main reason why dairy products can be considered unhealthy.

Although our bodies need fats for energy, growth and to absorb fat-soluble nutrients such as vitamins A, D and E, eating too much saturated fat, in particular, can raise levels of so-called ‘bad’ cholesterol in our blood. 

It can cause arteries to clog, leading to problems like high blood pressure and heart disease.

For decades we have been warned that eating too much dairy such as milk, butter and cheese could raise our risk of serious conditions such as heart disease and strokes ¿ only for more recent studies to suggest they might actually protect us from these

For decades we have been warned that eating too much dairy such as milk, butter and cheese could raise our risk of serious conditions such as heart disease and strokes — only for more recent studies to suggest they might actually protect us from these

Not unlike unsaturated fats found in fish, plants and nuts, saturated fats are more dense and difficult to digest for our bodies.

The NHS recommends men consume no more than 30 g of saturated fat per day, while women are advised to stick to a limit of 20 g. But a 200 ml glass of whole milk contains 7.4 g of fat, of which 4.8 g is saturated — a quarter of a woman’s daily saturated fat allowance.

Butter has around 80 percent fat and about 50 percent saturated fat. That’s equivalent to approximately 5.2 grams of butter per 10g serving.

Although the fat content of cheese can vary from 4 to % in cottage cheese, up to 35% in Stilton, and 44% in Mascarpone cheeses respectively; a Cheddar portion of 30g contains approximately 6.6 grams of saturated fat.

‘Consuming saturated fats like those in dairy raises our blood cholesterol levels,’ says Dr Giles Yeo, principal research associate at the MRC Metabolic Diseases Unit at Cambridge University and honorary president of the British Dietetic Association. ‘We need cholesterol as it gives our cells structure — it’s what stops us from being a puddle on the floor — but too much of it causes arteries to harden, which leads to cardiovascular problems.’

The main reason people in countries that consume high amounts of saturated fats are more at risk is because they have a higher chance of dying prematurely, especially from strokes and heart attacks.

In the case of dairy, it¿s certainly true that several studies observing large groups of people have failed to find a clear association between higher levels of dairy consumption and increased heart health risks

In the case of dairy, it’s certainly true that several studies observing large groups of people have failed to find a clear association between higher levels of dairy consumption and increased heart health risks

However, the link between saturated fat consumption and cardiovascular problems isn’t clear. Although scientists agree that high levels of saturated fat in the bloodstream can increase risk factors for cardiovascular disease and heart disease, it’s not certain that they directly cause heart problems.

Researchers believe saturated fat has been wrongly stigmatized. Arne Astrup, a professor in the department of nutrition, exercise and sports at Copenhagen University, argues that focusing on saturated fat alone ‘does not make sense’ as there are different types of saturated fatty acids which all have different effects on the body.

‘The effect is dependent on the food source it exists in — the effect of saturated fat is modified by all the other nutrients in the food,’ he wrote in 2019. 

Is eating milk protective? 

In the case of dairy, it’s certainly true that several studies observing large groups of people have failed to find a clear association between higher levels of dairy consumption and increased heart health risks.

There is a theory that this is because the other elements in dairy, such as calcium and certain fatty acids, work together in what is known as the ‘dairy matrix’ to protect our cardiovascular health.

However, scientists haven’t yet discovered how it might happen. But a 2018 study of more than 135,000 people in 21 different countries, who were monitored for nine years by researchers from McMaster University in Canada, found lower rates of death and cardiovascular disease in people who ate dairy than those who didn’t, with those who ate the highest amounts — two or more servings per day — the most protected.

A study published in September in the journal PLoS Medicine looked at 4,000 60-year-olds in Sweden (where diets are typically high in dairy) and found those who ate high levels were less likely to experience heart attacks, stroke or other cardiovascular problems — and were not any more likely to die than those who ate low levels.

‘A number of published studies suggest that, despite their saturated fat content, some dairy foods such as milk, cheese and yoghurt have a neutral or even positive effect on a person’s risk of heart and circulatory disease,’ says Victoria Taylor, a dietitian with the British Heart Foundation.

‘Studies have suggested that consuming dairy products is linked to a lower risk of type 2 diabetes and high blood pressure, both of which are factors that increase the chances of a heart attack or stroke.’

Under current recommendations adults and older children are advised to eat dairy in moderation, choose low-fat options where possible and avoid excessive consumption of butter or cheese

According to current guidelines, adults and seniors are encouraged to consume dairy moderately and choose low-fat alternatives whenever possible. They should also avoid eating excessive butter and cheese.

Calcium can stop fat absorption  

Some of the positive effects could be due to the beneficial nutrients found in milk foods. 

Protein and amino acids are found in milk, including calcium, vitamin B12 and potassium. These nutrients are vital to bone growth, repair and health. Iodine is also needed for thyroid hormones, regulation of metabolism, and other functions. These nutrients may help counteract the potential for damage caused by high fat levels.

‘There are several convincing studies to show that dairy foods are protective of our heart health,’ says Sophie Medlin, a dietitian with City Dietitians. ‘We think this may be due to the minerals in milk preventing full absorption of the saturated fats.’

High levels of calcium in cheese are thought to bind with fat in the gut, preventing some from being absorbed, so helping prevent it from raising ‘bad’ cholesterol levels.

In a 2017 European Journal of Nutrition study, it was found that people who consume 40g of cheese per daily have a lower risk of cardiovascular disease and stroke than people who don’t eat this amount.

Its authors attributed this to the probiotics — the ‘good bacteria’ —in cheese which they believe reduce the inflammation that can trigger heart disease. They also suggest that one of its fatty acids may boost levels of ‘good’ HDL cholesterol (which protects heart health) in the bloodstream and lower levels of ‘bad’ LDL cholesterol.

This could mean that cheese may not cause a furrowing of arteries like once thought and it might help prevent fatty plaques from forming on the walls of blood vessels. Another study has shown that some of the damages caused by cheese’s high levels of salt could be prevented by the antioxidants present in it during fermentation.

Scientists are still unsure how it works. Penn State University published a study in 2019 in which 11 participants tried different high-salt diets. It found that those who ate four cheese daily had lower blood vessel damage than people who ate other salt sources. 

Cheese: Question Marks 

Other experts, however, aren’t convinced. ‘This [theory that cheese could be beneficial for our health] speaks to the broader point that we eat a food rather than individual macronutrients, and the complexity of food means that there are good bits and bad bits, and how they interact also changes how good or bad they are,’ says Dr Yeo.

‘So this may be possible but the short answer is: we don’t know yet. There is still no evidence that having higher levels of saturated fat in your diet is a good idea.’

It is important to note that most studies on dairy consumption were observational. Researchers look at people’s diets and track what affects their health over the years. This type of study can’t prove cause and effect or explain why there might be an association between eating certain foods and developing certain illnesses.

Dr Yeo explains that randomised, double-blinded studies are the best for science. Participants are randomly assigned a placebo or a treatment and neither the participants nor researchers are privy to which.

This is a problem with diet studies because most participants know exactly what they eat. ‘This means studies are open to bias,’ he says.This is why, despite a growing number of studies throwing doubt over the link between dairy and health problems, the NHS, the British Heart Foundation and the Government’s Scientific Advisory Committee on Nutrition say their advice on dairy is not changing.

Current recommendations recommend that older adults and children eat moderate amounts of dairy, opt for low-fat options whenever they can and limit their intake of butter and cheese.

It means that there should be no more than 2 to 3 portions per day of dairy. This is equal to 1/3 of a pint worth of milk, one small portion of cheese (or yoghurt) and one small piece of cheese. The advice is different for children, who are recommended to drink 350 ml of milk a day, as research shows it helps young children’s growth. 

Sugar and salt concerns 

Dr Elijah Behr, a consultant cardiologist at Mayo Clinic Healthcare in London, agrees it’s too early to change dietary recommendations, particularly as we generally eat too much saturated fat already — the diet of the average Briton contains 12.6 per cent saturated fat, above the recommended maximum of 11 per cent — so it’s important we try to limit our consumption of fatty foods, such as fatty cuts of meat, sausages or biscuits.

He adds: ‘Recent research has suggested that it is not clear that dairy products will cause heart disease. However, these studies have limitations and, despite there being less consensus in the research community about whether dairy products are overall harmful or beneficial, we should be cautious before changing recommendations.’

Another flaw of many of the studies is they look at people’s overall consumption of ‘dairy’, ‘yoghurt’ or ‘cheese’ but do not differentiate between the specific types eaten.

Researchers believe that some ingredients in processed dairy products like sugar and salt could cause more harm than fat.

Plain full-fat yogurt may be healthier than low-fat flavoured, as they can have as high as 12 percent sugar. Sugar intake is associated with tooth decay and obesity.

Although lactose, a naturally occurring sugar in milk, isn’t considered to be harmful for your health. This complex sugar is slower than added sugars and releases more energy slowly.

But, salt added to dairy products like butter or cheese may raise blood pressure. This can increase the chance of strokes and heart attacks.

The NHS recommends that we consume no more than one teaspoon (6 grams) of salt each day.

But there is more salt in one matchbox-sized portion of Cheddar than in a packet of crisps, for example — around 0.5 g in the cheese compared to 0.4 g in a pack of salt and vinegar crisps.

‘Hard cheeses such as Cheddar are one of the biggest sources of salt in our diet and the sugar that is added to dairy products such as yoghurts, both whole milk and low-fat varieties, milkshakes and ice cream make dairy products a top source of free sugars in the UK diet,’ says Victoria Taylor.

What if the dairy nutrients are not added to foods? Sadly, we still can’t say for sure.

A Harvard University-led study that looked at the health of over 222,000 Americans published its findings in American Journal of Clinical Nutrition in 2016. It points out the confusion surrounding dairy. Researchers found no link between the consumption of dairy products and an increased risk of developing heart disease and stroke. But they did find that people who replaced dairy with vegetable fats or polyunsaturated fats — such as those found in fish and nut oils — saw their risk of developing these health problems drop by 10 per cent and 24 per cent, respectively.

Dairy consumption may not be harmful to your health but consuming less dairy could still prove beneficial.

Also, links to breast cancer have been challenged

To reduce breast cancer risk, should women cut back on dairy consumption? It is an issue that has been surrounded by controversy for a long time.

There is overwhelming evidence that dairy milk may raise breast cancer risk. A study in International Journal of Epidemiology published last year suggested that as little as 1 cup of milk per day could increase your risk by 50%.

Many reasons dairy foods should not be consumed include the possibility of high levels of growth hormones, fats, and oestrogen. A major study has shown that certain dairy products may actually be protective against breast cancer.

Indeed, the ‘comprehensive’ and ‘meaningful’ conclusions of the study, published last month in the journal BMC Cancer mean women should be encouraged to eat some types of dairy products, say the researchers from Zhejiang Chinese Medical University in China.

The research merged data from 36 studies from between 1986 and 2020, including information from more than a million women followed up for between 18 months and 22 years.It found that dairy can reduce the risk of breast cancer, particularly for oestrogen-receptor positive (ER-positive) and progesterone-receptor positive (P-positive) breast cancers, although this protection was not ‘statistically significant’ — meaning the protective effects identified may be just down to chance.

But, there were many variations in the amount of this protection. However, there are some exceptions. For instance, yoghurt or cheese may reduce the risk of breast cancer after menopause.

Contrary to what was shown in the last study, breast cancer risks were not increased by non-fermented dairy products like butter and milk.

It also affected the fat content in dairy products.

Low-fat dairy products (with a fat content of 1.0 to 1.5 per cent) offer protection against breast cancer in women before the menopause, while high-fat dairy products (3 to 5 per cent fat), are ‘harmful to [all] women’, increasing their risk of breast cancer, the study concluded. While more studies are needed, the researchers advise ‘low-fat dairy products for pre-menopausal women and fermented dairy products for post-menopausal women’.

They also recommend ‘minimising the intake of high-fat dairy products’ for all women.

It is possible that calcium, vitamin D, and conjugated Linoleic Acid (a type of Omega-6 fatty acids) found in milk can affect the growth of cells and inhibit tumor development.

Dairy may be particularly beneficial for protecting against hormone receptor-positive forms of breast cancer because its ingredients can ‘down-regulate’ oestrogen receptor activity, say the researchers.

With fermented dairy, the benefits may derive from probiotics or good bacteria it contains, which have been shown to protect against cancer by balancing bacteria in the gut (in turn affecting the body’s immune response, helping protect it from disease).

Researchers believe that probiotic levels naturally decrease with age. This may explain why women who have gone through menopause are particularly well served by fermented foods.

However, high-fat dairy may increase breast cancer risk. It can boost cell growth, as well as increasing the likelihood of type 2 diabetes and obesity (both related to the disease). The researchers say the ‘association between dairy intake and breast cancer risk is stronger in premenopausal women’, possibly owing to ‘more robust interactions’ between the different components in dairy in younger women.

Commenting on the study, Professor Kefah Mokbel, a breast surgeon at the private Princess Grace Hospital in London, said: ‘The assumption that dairy products contain significant amounts of oestrogens and growth hormones has led to the widespread belief that dairy products increase the risk of hormone-sensitive breast cancer.

‘But scientific evidence reveals that the theoretical increases in oestrogen concentrations following consumption of dairy are minuscule relative to circulating concentrations in humans.

‘Almost all epidemiological studies show that women consuming low-fat dairy products have a lower risk of breast cancer than those who don’t consume dairy, and fermented low-fat dairy products confer additional protection.’ 

Rachel Ellis