How Healthy is Dairy?
Updated: Sep 21, 2019
I just heard an advert about dairy. 'Love Irish dairy, and it loves you back!' We've been told for decades that drinking milk builds strong bones and helps to avoid osteoporosis or hip and other bone fractures in later life, as it increases bone mass. But does milk consumption really contribute to stronger bones and a healthier life? What is the environmental impact of dairy, and can milk production be sustainable? Let’s have a deeper look into dairy to find out more about this so-called health-supporting food group.
Growing up with dairy - healthful or harmful?
Most of the population in the Western world has grown up consuming a lot of milk and cheese, in the belief that we need it in order to stay vital and strong. Dairy is supposed to be good for bone health, as well as providing protein, vitamins and minerals. It seems to make its way into everything – you’ll find it on pizza, in salads, soufflés and ice cream, in yoghurt, butter, coffee, tea, cereals, pastries and cakes. The list is nearly endless.
Growing up in the 1980s, I consumed a lot of milk, cheese and cream, as I thought that dairy is an essential part of a balanced diet and healthy development. However when I started researching this topic in the past few years, I was very surprised to discover that the things I believed about dairy were not true. I wish I had learned about the problems associated with milk and cheese consumption earlier. I am sure that I would not have consumed so much of it, as it turns out that it is not as health supporting as I had always thought.
What exactly is cow's milk?
Like mother's milk is made for the needs of babies, cow's milk is made for calves. It consists of all the nutrients and hormones that a calf needs to grow as quickly as possible. A calf gains weight about 40 times faster than a human baby, and so cow’s milk is packed with hormones, fat and protein. These components change regularly to fulfil the needs of the calf.
Cows, like any other mammal, only give milk after having a baby. That's why they have to be impregnated as well as give birth to a newborn yearly. Otherwise, milk production cannot be guaranteed. Calves are separated from their mothers shortly after birth, so that humans can drink their milk. This milk is packed with the nutrients that calves need to grow into a mature cow, however, it is not needed by or designed for the human body.
Milk from pregnant or breastfeeding cows contains high levels of steroid hormones such as oestrogen, progesterone and other growth factors. These hormones have been found to contribute to the development of hormone-sensitive cancers such as prostate, ovarian, breast, uterus, testes and endometrium cancer.
A Japanese study, for example, found that the intake of exogenous oestrogen through the consumption of cow's milk changes the hormone levels of men, women and children. After consuming milk, the testosterone and gonadotropin secretion decreases, while the estrogenic level, as well as other female hormone levels, significantly increase. This may affect cancer growth and influence the sexual development of prepubescent children. (1) One reason for this change in hormone levels is due to the number of female sex steroids in milk products, which is 60-80%. Eggs, meat and fish contain only 10-20% of steroids, and vegetables do not show any oestrogen levels. (2/3)
As most people in the Western world consume milk regularly, these hormone levels accumulate in the body, and the risk of cancer development and prepubescent adjustments increases significantly. Higher levels of hormones in men who consume milk may more than double the risk of prostate cancer (76%), quadruple the risk of developing metastatic cancer, and the risk of developing fatal prostate cancer increases to 141%. (4)
Another factor which contributes to the risk of prostate cancer is the hormone IGF-1. IGF is the short form for insulin-like growth factor. This hormone plays an essential role in cell proliferation and cell death, as well as brain development. (5) A defining characteristic of cancer is uncontrolled cell proliferation. Therefore, IGF-1 plays a huge part in causing or preventing tumour growth.
Our bodies are constantly exposed to pollution, radiation, chemicals and other carcinogens which affect cell mutation and can result in cancer cells. Our immune system is able to destroy these cells before they divide and cause problems. However, IGF-1 inhibits cell death so that cell growth is adversely affected, and tumours can grow uncontrolled. As Cow's milk is composed of IGF-1, so that calves grow up very fast, drinking it boosts our IGF-1 levels and increases the risk of cancer tremendously.
But IGF-1 is not only found in cow’s milk. It is also produced by the human body in very small amounts and it seems to be nutritionally regulated. This means that animal protein – which is rich in essential amino acids – has a stimulating effect on the synthesis and action of IGF-1. Plant protein, on the other hand, is less abundant in essential amino acids and therefore, does not have any effect on this steroid hormone. (6) Consuming dairy and other animal products raise IGF-1 levels in the body. Studies have found that vegan men have significantly lower IGF-1 concentration in comparison to non-vegan men, and vegan women have a 13% lower amount of this hormone compared with meat-eaters and vegetarians. Only a small 8% increase of the serum was discovered in men who subsequently developed prostate cancer. This shows that only a minor change in the amount of IGF-1 can determine a change in cell multiplication. (7/8)
Besides IGF-1, there are other components in milk such as the proteins casein and whey that also increase the risk of the growth of prostate cancer cells. Studies found that milk plays a significant role in the growth of prostate and other dairy-promoted cancers due to its high amount of steroids and hormones. (9) However, putting people on a whole-foods, plant-based diet without any other lifestyle changes has shown that the growth of prostate cancer cells was inhibited by almost 8 times more than in the control group. (10) Another study also found that you can “switch off” cancer cells by switching to a plant-based diet. (11)
Milk consumption in general contributes to a variety of health issues – from atherosclerosis, to arthritis, to cancer. Women who consume milk products, for example, have a higher risk of getting breast cancer. This risk is linked to the proteins whey and casein, saturated fat, as well as hormones in milk.
The lactose in milk raises the risk of ovarian cancer, and is also related to other significant health risks for women. The China Study concluded that dairy is responsible for some cancers in children, and Dr Neal Barnard discovered a higher risk for Type 1 Diabetes in children who were exposed to non-human dairy milk in the first year of life.
This was only a short discussion on some examples of milk-related diseases. More information about the health risks caused by milk consumption will be discussed in future blogs. Unfortunately, milk is not only a threat to human health – but also to the environment.
But first, I want to stress that it does not make sense from a biological perspective to consume milk from another species. Mammals show a high lactase activity in infancy but this decreases to very low levels after weaning which makes physiologically complete sense. The same is true in humans. Looking at Caucasian adults, for example, only 5-15% have the ability to consume dairy milk due to their low levels of lactase activity. (12)
If you think you need to drink milk for getting the recommended daily amount of protein and calcium, let me tell you that there is enough calcium in leafy green and cruciferous vegetables, as well as a high amount of protein in grains. And unlike dairy, plants contain no saturated fat, no hormones, and do not cause diabetes or otherwise harm the body in any way.
The production of dairy also requires a huge amount of water. Especially today, with the climate getting warmer, and with water shortages in many countries throughout the world, it makes sense to reduce dairy production to a minimum (or to get rid of the dairy industry altogether).
Water for dairy is used for cows to drink, stay hydrated and cool off. It is also used for sanitising the facilities, irrigating the crops, the milking process and cooling the milk. As you can see, water is a very important element in the production of dairy. It takes several hundred litres of water to produce 1 litre of milk in Ireland, but depending on the country and milk production system,
it can take up to several thousand litres of water to produce only 1 litre of milk.
Another problem is water pollution that affects the land, rivers, and sea. Herbicides, pesticides and manure are washed into our rivers and find their way into the sea. Not only across Ireland, but also Europe, the Mississippi delta, India and China are so-called “Dead Zones” caused by permanent nutrient pollution. In these zones, hypoxic areas have built up, which deplete the oxygen, so that marine life is not able to survive anymore. The excess in nitrogen and phosphorus levels caused by animal manure, fertiliser and plant protection agents is responsible for an overgrowth of algae, causing algal blooms, which usually happen in warmer weather.
Milk is also heavily subsidised by the government, and dairy would never be so cheap without state assistance. It is even cheaper than water. When you see the amount of land used for growing crops and breeding cattle – as well as the whole process behind milk production – you might wonder how this is possible, and you begin to realise that it is only possible with our tax money. Why not use this money to support organic fruit and vegetable farms? We would have a variety of local fruit, vegetables, grains and legumes to eat – and support our health as well as the environment.
Sonja from SOS Free