Dairy still scary? New research on the heart benefits of milk, cheese and butter

by Sally Blundell / 28 October, 2018
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Fear of full-fat milk is tipped on its head by new findings on stroke and heart disease. So what milk is best – and could dairy products help turn around our children’s poor nutrition?

The froth on our coffee, the dash in our tea, the splash on our cereal – our hankering for milk is as unquenchable as it is questionable.

Some say it is just plain wrong – all other mammals nurse only until they are ready for other food, then a gene steps in to shut down the ability to produce lactase, the enzyme that allows babies to digest the milk sugar lactose. It is only through an evolutionary twist that about 40% of humans, particularly those in Europe, the Middle East, North Africa and the Indian subcontinent, lack this gene and so continue to consume milk into adulthood. For the remaining 60%, dairy consumption can cause a range of symptoms such as cramping, bloating, gas and diarrhoea.

Others warn of milk’s high fat content. If they consume milk, they opt for the no-fat, low-fat, lactose-free and trim versions. Most current dietary guidelines, including in New Zealand, recommend 2-4 servings of fat-free or low-fat dairy per day, in the belief that saturated fats adversely affect blood lipids and increase the risk of cardiovascular disease.

But a new study says a glass of full-fat milk, a pottle of yogurt and a slice of cheese every day actually lower the risk of heart disease. The Canadian-led Pure (Prospective Urban Rural Epidemiological) study, involving more than 135,000 people aged 35-70 in 21 countries, found those who eat three servings of dairy a day (one serving being a glass of milk, a cup of yogurt, a 15-gram slice of cheese or a teaspoon of butter) had lower rates of cardiovascular disease and lower mortality than those who ate less. As reported in the Lancet, butter was not seen to be protective, but the intake was so low it was not associated with any clinical findings.

This is not the first study to drive a nail through our fear of dairy fat. In 2014, the American Journal of Clinical Nutrition cited research showing people whose dairy consumption was very high had a significantly lower risk of diabetes than people whose dairy consumption was very low. Although a 2017 Swedish study found having two or more servings of milk a day was associated with a 32% higher risk of mortality, the Lancet study reminded readers that the daily intake of dairy in Sweden is markedly higher than that on which the Pure research is based.

New Zealanders are the third-highest consumers of fresh milk per capita in the world, but our dairy habits are changing. Since Time ran its “Ending the War on Fat” cover story in 2014, butter sales, says Fonterra head of research and development Mark Piper, have increased whereas sales of zero-fat milk are declining. This year, Fonterra opened a new $15 million cream cheese factory in Darfield that is expected to make up to 24,000 tonnes a year.

“There was a lot of bad science showing dairy fat in particular was bad for you – only recently has a lot of that been debunked,” says Piper. “Fat gives a flavour and a taste that is hard to replicate.”

Professor Rod Jackson. Photo/Stephen Robinson

Rod Jackson, professor of epidemiology at the University of Auckland’s School of Population Health, won’t have a bar of it. Long-term studies such as the Pure study, he says, are impossible to do well. People often forget what they have eaten the week before, over a 5-10 year period their diets can change and what is eaten cannot be teased out from other lifestyle factors such as smoking, drinking and exercise. And for this research, he says, the results also depend on how much other saturated fat you eat and what sort of dairy you are consuming – high fat or low fat, butter or yogurt?

“Yogurt is made from whole milk – it has a bit of fat but it also has protein and calcium. Cheese is made from whole milk, but butter is just the 5% of milk that is fat – it has no protein, no calcium. People say butter is natural but it is a highly refined, highly concentrated form of saturated fat, and there is good evidence that eating a diet high in saturated fat is not good for you. Butter doesn’t come out of a cow, milk does. Excuse the pun, but they are like chalk and cheese.”

Debates about the risks and benefits of dairy will not end any time soon. Even without taking into account large-scale dairy farming’s urgent environmental issues and ongoing animal welfare concerns, figuring out if the white stuff is the right stuff continues to befuddle scientists, as it has for centuries.

“Milk is a test case in the most pressing issues in food politics,” says US writer and food historian Mark Kurlansky, author of global food chronicles Cod and Salt, “from industrial farming and animal rights to GMOs [genetically modified organisms], the locavore [local food] movement and advocates for raw milk.”

Kurlansky’s latest book, Milk! A 10,000-Year Food Fracas, explores the complex story of the “most argued over food in human history”.

Cows’ milk has four times as much protein as human milk and lacks linoleic acid, important for human brain growth. In Europe, in the early Middle Ages, it was third on the preferred list after goat and sheep milk, Kurlansky notes. But cows have come to dominate the global dairy sector: they are easy to domesticate and, per animal, produce a tremendous amount of milk: 25-30 litres a day compared to a goat’s 3.7 litres a day.

Milk, a source of nutrients, is handed out in more than 1400 New Zealand schools. Photo/Getty Images

Milk, a source of nutrients, is handed out in more than 1400 New Zealand schools. Photo/Getty Images

Fuelling conquest

The Mongol conquest of most of Asia and Eastern Europe was achieved by a soldier’s diet of koumiss (fermented mare’s milk) and dried cows’ milk curds, enabling them to ride for long hours without stopping.

But not everyone embraced such a diet. Southern Europeans long regarded the greater consumption of dairy foods by their northern neighbours as evidence of their barbarian nature. The Dutch, in particular, were singled out as a crude and comic people or kaaskoppen, “cheese heads”. But the Dutch, English, French, Spanish and Portuguese were also the milk-drinking conquerors. Off they sailed with their bovine cargo, most commonly the large black and white holstein-friesian from the Netherlands, to America, Australia and New Zealand.

With increasing urbanisation and milk production, quality became a serious issue. A freshly drawn bucket of milk starts growing dangerous bacteria within minutes, especially when buckets are not particularly clean. In large cities like London, milk was carried through dirty streets in open and often unwashed pails; the risk of contamination was huge.

Consumers paid the price as milk was mixed with chalk, molasses and other additives to improve colour, texture and quantity. By the late-1800s, tuberculosis, cholera, scarlet fever, diphtheria and typhoid were all traced back to milk.

By the early-1900s, much of the US had mandated pasteurisation, which involves heating milk to just below boiling point then rapidly cooling it (it became mainstream in New Zealand in the 1940s). The alternative, a process of monitoring and certification, was considered too expensive. Still, the debate rumbles on: more than half a million Americans a year buy unpasteurised milk. From a taste and nutrition perspective, Kurlansky tells the Listener, “raw milk is better; the issue is, can it be safely regulated?”

Fonterra’s Mark Piper.

The development of the milking machine saw the move to ever bigger dairy herds. In New Zealand, the average herd size has grown from 166 cows in 1990 to 414 cows in 2016-17; in the US, herd numbers can be in the thousands.

Increasing scale gave some economic security for a low-cost commodity but there have been ongoing health scares. In 1973, animal feed in the US was found to contain the flame retardant polybrominated byphenyl, or PBB. GMO-based recombinant bovine growth hormone (rBGH) to boost milk production further alienated some American consumers. In the UK and Western Europe, outbreaks of bovine spongiform encephalopathy, or mad cow disease, caused by concentrated feed including cheap meat and bone meal, drove worried consumers to the organic milk shelves or plant-based milk alternatives. China’s lack of trust in its own milk was aggravated by the melamine poison scare in 2008, when more than 300,000 babies became ill and six died. The Sanlu Group, in which Fonterra had a 43% stake, was found to be the source of the poisoned milk but other dairy companies have since come under suspicion. Many believe that not all the culprits were found, Kurlansky reports.

Outside hormones, genetic modification, chemicals and antibiotics, he concludes, there remains a fundamental question that, after 10,000 years, has still not been answered: “If a dairy did everything right and its milk was perfect, would it be good for you? After all, adults drinking milk is not natural; neither is babies drinking anything but their mothers’ milk.”

Dairy products do contain specific amino acids, natural fats, vitamins K1 and K2, calcium, magnesium and potassium. New research is looking at the potential of probiotics isolated from milk to alleviate maternal depression and anxiety after birth and to reduce the risk of gestational diabetes and the incidence of childhood eczema.

Others argue all the nutrients present in milk can be sourced from other foods. US advocacy organisation Physicians Committee for Responsible Medicine urges a dairy-free diet and denounces feeding animal milk to children. In 2012, the Advertising Standards Authority in this country upheld complaints regarding Fonterra’s claims that dairy is an “essential part of a balanced diet” and “we all need it”. We don’t, but dairy is still a cheap and readily available source of nutrients.

Nutrition Foundation scientific director Elaine Rush.

As part of a varied, largely plant-based diet, says Elaine Rush, scientific director at the New Zealand Nutrition Foundation, dairy can help turn around our poor health outcomes. “We need to look at the whole picture, be holistic and also think of the world and its future rather than focus on one food or nutrient. We are one of the most poorly nourished countries in the OECD because of our overweight and obesity. Almost one in three adult New Zealanders is obese, and one in 10 children – that is malnutrition.”

She points to the success of Project Energize, a programme now being used in 242 primary schools aimed at encouraging physical activity and healthy eating, including “the consumption of milk and other high-calcium foods every day”. Already, she says, participating schools have seen a 3% decline in childhood obesity. In a rerun of the 1950s, Fonterra is now giving out 200ml packs of UHT milk to children in 1420 schools around the country.

Despite recent findings on saturated-fat dairy, says Rush, low-fat dairy still has a place.

“If you take the fat out you increase the protein and water-soluble calcium, so you get more protein and calcium for your money. I am not anti-fat but there is evidence against saturated fat.”

Jackson agrees. “I am not against eating dairy,” he says, “but I am against eating a diet high in saturated fat.”

For the 60% of the world defined as lactose intolerant, fat content is irrelevant. After all, once the gene responsible for the production of lactase has been switched off, it cannot be switched back on. But there is growing support for the idea that, over generations, lactose tolerance can develop to meet a growing dependency on dairy foods.

“Though most black Africans are lactose-intolerant,” Kurlansky writes, “the Massai, who are cattle herders, are not. Those who are intolerant tend not to have dairy in their culture. Though most Europeans drink milk today, we don’t really know the original extent of lactose intolerance on the Continent, because centuries ago, milk drinking there was rare. Hard cheese and yogurt were popular, but they do not contain lactose.”

And dairy intolerance in general may be over-stated. China has long been regarded as a lactose-intolerant nation, largely on the basis that so little dairy was consumed there. However, the first mention of milk in China dates back to the Han dynasty (206BC-220AD). Since then, China’s more privileged classes have continued to enjoy dairy products. The Chinese are now eating ever more dairy and it has become the world’s fourth-largest milk producer, after India, the EU and the US. Today, almost 40% of Chinese drink milk, and the use of infant formula is widespread.

In some cases, a diagnosis of lactose intolerance may well be masking symptoms related to a specific protein in the milk, rather than milk itself. Keith Woodford, former professor of agribusiness at Lincoln University and author of the 2007 book Devil in the Milk: Illness, Health, and the Politics of A1 and A2 Milk, says there is “intriguing evidence” that a lot of diagnosed lactose intolerance is actually A1 beta casein intolerance.

Researcher and A2 proponent Keith Woodford.

A1 and A2 proteins are different forms of beta-casein that make up about 30% of the protein content in cows’ milk. Originally, all cows had only the A2 protein. The A1 protein is the result of a chance mutation 5000-10,000 years ago in northern Europe, originating, it is thought, in the black and white cows in northern Germany and the Netherlands that then carried their protein-determining genes around the world.

When digested, A1 beta-casein releases beta-casomorphin7 (BCM7), a mu-opioid with a structure similar to that of morphine. Scientists, beginning with Bob Elliott, professor of child health research at the University of Auckland in 1993, have long suspected BCM7 is a problem.

Mu-opioid receptors are responsible for peristalsis, the system of muscle contractions that moves food through the digestive tract, but the presence of BCM7 appears to slow that process. The longer that process, the more fermentation occurs within the gut system and the more scope there is for bloating and other markers of digestive discomfort. Even if there are no obvious digestive symptoms, there are other auto-immune and neural conditions related to BCM7, including diabetes, heart disease, eczema and asthma.

A 2009 study in Russia found formula-fed infants who could not metabolise BCM7  had delayed muscle tone and psychomotor skills compared with infants fed only A2 milk. “We know with reasonable confidence that this slowdown of passage will be occurring in everyone,” Woodford says. “But how people react to that will depend on other aspects of their system. Some people will get strong inflammatory reactions, others won’t be aware of it.”

Initially, there was strong resistance to A2 milk from major milk companies. A 2009 review by the European Food Safety Authority found no link between A1 milk and human disease but did not consider digestive problems.

But the tide has changed – and dramatically. A2 milk is now sold in about 10,000 stores in China, 2000 in the UK and 6000  in the US. Nestlé has an A2 milk product in China, the world’s largest infant formula market. Chinese dairy giant Mengniu also has an A2 product.

“I think we can say with confidence every big dairy company in the world either has an A2 project or it is looking at it very closely,” says Woodford.

The a2 Milk company has recently doubled its stake in Synlait Milk, which makes  infant formula for the lucrative Chinese market. This year, after being at odds for close to two decades, Fonterra and a2 Milk joined forces to offer a jointly branded A1-free milk under the Anchor brand.

The increasing availability of A2 milk, Fonterra’s Piper says, is not so much a response to health claims but consumer demand. “We believe true lactose allergies are overdiagnosed. People say they have been lactose-intolerant but they can drink A2 milk. But it’s the same lactose in A2 and in A1 milk, so it’s not just lactose intolerance.”

Last year, a2 Milk’s shares hit a record as appetite in China and Australia for its infant formula products saw annual profits improve 200% on the year before, to $90 million. This year, profit reached $196 million.

Peter Nathan, of a2 Milk.

“A decade or so ago, we were perceived to be a bit weird,” says Peter Nathan, Asia-Pacific head of a2 Milk. “Now, as a business, it is commercially strong. The beauty of the A2 proposition is it is natural, as opposed to a functional milk that has been artificially changed such as lactose-free or other modified milk.”

As demand for A1-free milk increases, providers of bull semen are now selecting for A2-A2 genes. Today, about 35% of Australia’s dairy herd is A2. In New Zealand, it is slightly higher, largely the result of a greater level of jersey genes in our herds (although farmers can change their herd to A2 without changing breed).

Whether it is A1 or A2, low fat or whole fat, pasteurised or raw, milk is not going to be scratched from our shopping lists any time soon. To Kurlansky’s question, “Is dairy good for you?”, Rush responds yes, but only as part of a broader plant-based diet.

“We are meant to be eating a varied diet of food from different groups – ‘not too much, mainly plants’. We need to look at the whole picture, be holistic and also think of the world and its future rather than focus on one food or nutrient.”

In Kurlansky’s home town of New York,  people are drinking less milk, he says. But New Zealand is holding its own in the dairy statistics. According to the NZ Beverage Council, milk is still the most frequently bought beverage in the shopping trolley. And consumers are becoming ever more discerning.

Boutique dairy company Lewis Rd began with a top-shelf butter but hit its stride in 2014 when its Whittaker’s chocolate milk flew out the door as fast as the checkout operators could scan the code. By then, global trends were swinging back towards dairy, but it is the premium end of the milk market, says founder and chief executive Peter Cullinane, that is showing growth.

It has now just launched its new “gold top” brand, a premium organic non-homogenised A2 milk from a jersey herd in Matamata packaged in glass and recyclable plastic bottles.

“A lot of our attention in the last 100 years has been on the biggest volumes at the lowest cost but New Zealand should make the best dairy products – we have the best raw ingredients in terms of land and the farming skills to do that.”

This article was first published in the October 6, 2018 issue of the New Zealand Listener.

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