Milk: from healthy to harmful

Nothing is more terrible than ignorance in action.

Johann Wolfgang von Goethe

Introduction

In the 1930s, Sir John Boyd-Orr recommended that we in Britain should drink more milk to improve our health. He was talking of full-cream milk, of course; skimmed milk was fed to pigs. Since then, milk and dairy products have been heavily promoted for their health-giving properties. But, although cow's milk is still enthusiastically promoted as providing adults with 'essential' vitamins and minerals, after the Committee on the Medical Aspects of Food Policy (COMA) introduced us to 'healthy eating' in 1984, the dogma about fat causing heart disease has transformed milk from healthy, fresh whole milk to a product which is utterly denuded of most of its essential nutrients — the most important of which is the fat in its cream.

How milk is processed

When I was young, milk was collected from a local farm, cooled and then delivered to households by horse and cart. At the door, the milk was measured out with a half-pint ladle. The cream floated naturally to the top of the churn; the delivery man had to stir it to make sure that everyone benefited. My mother had young children, so our milkman was careful to ensure that we got a bit more cream by ladling the creamier milk off the top. The milk was no older than the previous evening's milking. We were healthy in those days.

Today, raw milk is collected from farms daily for delivery to dairies by tanker for storage and processing. To make it 'safe for drinking' the raw milk is then heat-treated at a variety of temperatures to kill any bacteria and increase its shelf life. The lowest temperature is used in pasteurization; the highest is UHT (ultra-high temperature). Most milk in UK is pasteurized.

After pasteurization, milk to be sold as liquid milk is separated from its cream in a centrifuge. With the cream separated from it in this way, we are left with skimmed milk. The cream is then blended back into the skimmed milk in measured amounts to produce whole milk — 3.3% fat although whole milk would be over 4% naturally — and semi-skimmed milk (1.7% fat). Excess cream is sold as cream or used to make butter.

During the blending process the fat globules in the cream are usually broken up and dispersed throughout the liquid milk to give the finished product a more uniform texture. This process, called homogenization, also prevents the cream from rising to the top. Whole milk in supermarkets is homogenized.

After the entire process has been completed, the milk is heat treated yet again and then cooled before being packaged and sold to retailers.

Other than the addition of the cream back into the milk, every step in this process makes the finished product less and less healthy for consumers.

Skimmed milk and prostate cancer

Around 1975, scientists noted an apparent strong correlation between milk intake and deaths from prostate cancer. Since then, there have been growing suspicions of a causal link between the two which two studies published in 2007 appeared to confirm. The first was the CLUE II study which involved nearly 4,000 men in Washington County, Maryland.^[1] This study found that men who consumed five or more servings a week of dairy foods were more likely to suffer from prostate cancer than those who ate a serving of one or less. The second study involved over 29,000 Finnish men taking part in the Alpha-tocopherol, Beta-Carotene Cancer Prevention Study (ATBC Study) which ran for 17 years.^[2] This also found that the more dairy consumed, the higher the risk of cancer.

The first thing to be blamed for such an association, as it always seems to be, was the saturated fat in the cream.^[3] But mounting evidence suggests that the truth is quite different because full-cream milk does not increase prostate cancer risk, only skimmed milk does. It was the stripping of fat from the milk — to make it 'healthier' — which actually increased the risk.

The 11-year Physicians' Health Study, involving over 20,000 men, found that all the increased risk of prostate cancer associated with dairy intake was attributable entirely to skimmed milk.^[4]

In 2005, the first National Health and Nutrition Examination Epidemiologic Follow-up Study (NHEFS), involving more than 3,600 men and 10 years of follow-up, arrived at a similar conclusion. They found that men with the highest intakes of dairy were more than twice as likely to develop prostate cancer as men with the lowest intakes. But the risk was higher only with low-fat milk — not with whole milk or any other dairy. In fact, whole milk actually seemed to protect against prostate cancer.^[5] Similar results were found in other countries. A Norwegian study of more than 25,000 men,^[6] and an analysis of milk drinking and diet in 41 countries,^[7] found that prostate-cancer death rates were associated only with the drinking of low-fat or skimmed milk.

Low-fat milk increases women's cancers too

Women are presently encouraged to consume dairy products as a source of calcium to prevent osteoporosis. And, because of the fat scare and the fact that all the calcium is in the milk, not in the cream, the milk women are advised to drink is skimmed.

Studies have looked at dairy intake and rates of ovarian cancer and found an increased ovarian cancer risk with milk drinking. But just as in the case with prostate cancer in men, there is no increased risk with whole milk; only with low-fat milk and skimmed milk. The Iowa Women's Health Study investigated the association of epithelial ovarian cancer with dietary ingredients in a study of 29,083 postmenopausal women.^[8] They found that skimmed milk, but not whole milk, was significantly associated with an increased incidence of ovarian cancer.

An even larger study published six years later confirmed the Iowa results. In the Brigham and Women's Hospital Nurses' Health Study, in which more than 80,000 women participated, those who consumed just one or more servings of skimmed or low-fat milk products per day had a 32% higher risk of any type of ovarian cancer, and a 69% higher risk of the most widespread form — serous ovarian cancer — compared with women who had three or fewer servings monthly. Yet again, whole milk did not increase the risk.^[9]

References

1. Rohrmann S, et al. Meat and dairy consumption and subsequent risk of prostate cancer in a US cohort study. Cancer Causes Control 2007; 18: 41-50.
2. Mitrou PN, et al. A prospective study of dietary calcium, dairy products and prostate cancer risk (Finland). Int J Cancer 2007; 120: 2466-2473.
3. Willett WC. Nutrition and cancer. Salud Publica Mex 1997; 39: 298-309.
4. Chan JM, et al. Dairy products, calcium, and prostate cancer risk in the Physi-cians' Health Study. Am J Clin Nutr 2001; 74: 549-554.
5. Tseng M, et al. Dairy, calcium, and vitamin D intakes and prostate cancer risk in the National Health and Nutrition Examination Epidemiologic Follow-up Study cohort. Am J Clin Nutr 2005; 81: 1147-1154.
6. Veierod MB, et al. Dietary fat intake and risk of prostate cancer: a prospective study of 25,708 Norwegian men. Int J Cancer 1997; 73: 634-638.
7. Grant WB. An ecologic study of dietary links to prostate cancer. Altern Med Rev 1999; 4: 162-169.
8. Kushi LH, et al. Prospective study of diet and ovarian cancer. Am J Epidemiol 1999; 149: 21-31.
9. Fairfield KM, et al. A prospective study of dietary lactose and ovarian cancer. Int J Cancer 2004; 110: 271-277.

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