Our milk article got a passionate response from many different angles. Perhaps the most common response was that people were surprised to discover that our milk is being watered down. Others condemned the intensification of our dairying and the reliance on palm kernel required to all these cows fed over autumn. Some felt that we had missed the real scandal by overlooking the impact of pasteurisation (heat treating milk to kill bacteria) and homogenisation (breaking up the fat globules so the cream mixes in). We will focus on these two issues in this blog.
Does pasteurisation make any difference? Not to taste; at least if our very unscientific taste test is any guide. A couple of passionate suppliers of milk sent in some samples to show off how their product was different. We thought we would have a bit of fun with the product we got sent, so we got hold of some raw milk and held a little in-house Morgan Foundation milk taste test. Of course this isn’t an attempt at definitive science: it is only a sample of four, and it is just a blind taste test so it tells us nothing about the nutritional value of the different milk. That said, we could only distinguish the non-homogenised Jersey milk – no surprise given the chunks of cream in it – but the others (including the non-pasteurised, non-homogenised raw milk) were indistinguishable from the mass produced supermarket stuff. You can watch the video we made here.
But the real question is whether homogenisation and pasteurisation are actually bad for us. There is a case to be made here – after all in our book Appetite for Destruction we found that generally the less processed a food is, the more nutrients it has. But that doesn’t mean that all processing is bad. There are trade-offs, particularly between food safety and the amount of nutrients in the food. In all processed food we need to strike a balance between these.
The advocates of raw milk tend to follow the diet advice of a chap called Weston Price. He was a slightly quirky dentist who travelled the world in the 1930’s to investigate the impact of Western diets on native peoples. He did this by following the roads being built into remote villages, and observing the changes in diet and health caused by their commerce with the outside world. He found that many of the problems we now visit a dentist for were non-existent in people with native diets. We’re not just talking plaque and tooth decay: he found that native people never needed braces or had problems with abscesses and wisdom teeth. He theorised that the Western diet was to blame.
Weston Price generally found that each tribe had developed ways to get their essential vitamins and minerals from their local environment. Being a dentist, he focused particularly on the fat-soluble Vitamins A and D (which have many benefits, including improved immunity, and combine with calcium and phosphorus to make bones and teeth) and a special Vitamin ‘activator’ (probably Vitamin K2). He found most native peoples got these vitamins from eating animal products. Most of the native diets were far less varied than ours, and yet he found that the level of these vitamins in their food was often ten times our official dietary requirements. Levels of other minerals and water-soluble vitamins were about four times higher than the typical Western diet. Is this the ideal level of nutrients our bodies require to truly thrive? Modern science can’t provide the answer: it can only tell us when we have a nutrient deficiency.
Weston Price’s followers argue that minimal processing is essential to retain the quality of food. They believe that pasteurisation (heating milk to kill off most of the bacteria that could cause serious harm to humans) and homogenisation (mixing milk to prevent the fats separating out and settling on top) destroys nutrients, kills off the good bacteria and enzymes that help humans digest milk nutrients, and can fundamentally change the chemical make-up of the milk itself. They are not so worried about cheese and yoghurt, which has good bacteria added back in.
Studies have shown that there is some evidence behind these concerns, but the short answer is that the health implications of homogenisation and pasteurisation are not fully understood. Pasteurisation is a heat treatment which rids milk of harmful bacteria, but might get rid of some good bacteria too. Some proteins, vitamins and antioxidants may also be damaged by pasteurisation. We also don’t know much at all about the impacts of homogenisation, which breaks fat globules up into smaller bits so that your milk as a smooth consistency instead of the cream on top.
But we do know that the downside of not pasteurising the milk is an increased risk of getting food poisoning. This is not a trivial issue – particularly with a mass produced and distributed milk supply. It is all very well for the middle class worried well to get their milk from the farm gate, but is it a viable way to deliver milk to the masses? Probably not, at least not cheaply. Of course the Weston Price crowd argue that if the cows are kept in sanitary conditions, and the supply chain is carefully controlled, pasteurising isn’t needed to keep the milk safe. That is a long way from the reality of many thousands of milk suppliers that comprise the New Zealand dairy scene so far better to use pasteurisation to be safe.
This is why it is still illegal to sell raw milk through the retail networks in New Zealand, which means the Weston Price followers and other milk connoisseurs are forced to buy it directly from the farm gate. Homogenisation is a different story, as it is perfectly legal to buy non-homogenised milk, although few people choose to.
Should the law on pasteurisation change? Frankly the science just can’t tell us what nutrient benefits we’re missing from pasteurisation so the risks that raw milk from the New Zealand dairy herd poses still dictates we pasteurise where raw milk from a plethora of farms is aggregated. In the meantime, scientists are exploring new ways of improving the safety of milk without heat treatment.