Tuesday, March 31, 2009

Raw milk - not the 'cure-all' it's propounded to be

It wasn't much fun being a dairy lover back in the late 19th and early 20th century. Although heating or boiling milk before it was fed to infants was known to reduce the incidence of disease and mortality, milk products were the cause of 25% of all cases of food and waterborne illnesses traced to source (1).

Luckily for us, in 1864 Louis Pasteur developed the process now known as pasteurization. Pasteurization involves heating milk to 161°F (71.7°C) for 15 seconds, performing the dual function of killing milk-borne pathogens and extending the time that milk stays fresh. Michigan was the first state to make milk pasteurization mandatory in 1947, and nowadays, the incidence of food-borne disease from milk products is <1%>

All sectors of animal agriculture are currently plagued by small but extremely vocal minorities, with enough spare disposable income to buy products that they perceive as being healthier, less-processed, locally-grown, environmentally-friendlier or more sustainable than conventional food products. The emphasis here is on the word 'small' - it's a niche market of customers for whom giving a child a twinkie rather than a macrobiotic whole-grain carob rice cake could be considered child abuse. However, it's a form of food elitism that's increasingly finding its way into the mainstream media (3).

So what claims are the granola-brigade making this time? The main claim appears to be that valuable nutrients are destroyed by pasteurization. According to one raw milk enthusiast via Twitter, pasteurized milk is 'dead'. The 'facts' (according to the raw milk lobby) suggest that raw milk contains proteins, vitamins, minerals, anti-cancer agents (conjugated linoleic acid) and a whole host of goodies (4), whereas pasteurized milk is a chemical soup of hormones (5) and saturated fats. Not surprisingly, this is nonsense propagated by non-scientists: no scientific, peer-reviewed study has shown any difference in nutritional value or composition between pasteurized and raw milk (6, 7).

However, there is one major difference between pasteurized and unpasteurized milk consumption: the incidence of foodborne disease. The presence of foodborne pathogens in raw milk samples has been documented by several studies including that of Jayaro et al. (8), who found Salmonella isolates in 6% of samples, Shiga toxin-producing E. coli in 2.4% of samples and Listeria monocytogenes in 2.8% of samples. In another study investigating E. coli outbreaks after raw milk consumption, Keene (9) concludes that "consumption of raw milk is a high-risk behavior and will continue to cause morbidity and mortality until people stop consuming raw milk and raw milk products". Finally, Gillespie et al. (10) reports that between 1992-2000, 52% of foodborne outbreaks in England and Wales were attributed to raw milk consumption.

More information on the risks of raw milk consumption is available from the US Food and Drug Administration here: http://www.fda.gov/bbs/topics/NEWS/2007/NEW01576.html and here: http://www.foodsafety.gov/~dms/rawmilk.html

I have no issue with people doing things that endanger their health. Want to drive without a seat-belt? Fine. Want to smoke 45 cigarettes per day? Go for it. Want to help yourself to a tasty cold beverage that has a 6% chance of containing Salmonella? Yummy. However, it should be a choice made based on science and relative risk. I lived on a dairy farm for ten years where everyone drank raw milk. Did anyone get ill? No. Were we all likely to be more resistant to the bugs found on dairy farms through working with the animals every day? Yes. Would I give raw milk to a child or immunosuppressed person? Not on your (their) life.

Milk is milk. Just make sure that the choices you make are informed by science, not granola.

(Endnote: One other intriguing claim is that raw milk was used to 'cure' illnesses from ~460 BC until WWII (3), the same period when, for example, trepanning (drilling holes in the skull to release evil spirits) was used to 'cure' epilepsy. Think the FDA might want to check the
efficaciousness claims for this one.)


(1) http://www.milkfacts.info/Milk%20Processing/Heat%20Treatments%20and%20Pasteurization.htm#PastHist

(2) Schmidt, R. H. and P. M. Davidson. 2008. Milk Pasteurization and the Consumption of Raw Milk in the United States. Food Protection Trends. Jan 2008. 45-47.

(3) http://lifestyle.msn.com/your-life/living-green/articlegreenchan.aspx?cp-documentid=18708415&gt1=45002

(4) http://www.raw-milk-facts.com/raw_milk_health_benefits.html

(5) http://www.realmilk.com/

(6) Potter, M. E. et al. 1984. Unpasteurized milk: The hazards of a health fetish. Journal of the American Medical Association. 252:2048–2052.

(7) LeJeune, J. T. and J. P. Rajala-Schultz. 2009. Unpasteurized milk: A continued public health threat. Food Safety. 48:93-100.

(8) Jayaro, B. M. et al. 2006. A survey of foodborne pathogens in bulk tank milk and raw milk consumption among farm families in Pennsylvania. Journal of Dairy Science 89:2451-2458.

(9) Keene, W. E. et al. 1997. A prolonged outbreak of Escherichia coli O157:H7 infections caused by commercially distributed raw milk. Journal Infectious Disease. 176:815–818.

(10) Gillespie, I. A. et al. 2003. Milkborne general outbreaks of infectious intestinal disease, England and Wales, 1992–2000. Epidemiology of Infection. 130:461–468

Friday, November 28, 2008

Organic milk doesn't contain hormones.

A commonly-heard reason for buying organic or rbST-free milk is that it 'doesn't contain hormones'... or does it?

It's a commonly-heard perception, but one that's simply not accurate.

Firstly, all milk contains hormones. That applies whether it's from a cow, goat, sheep or even a human; whether the animal has been raised conventionally, on pasture or organically; and regardless of whether the animal has been given supplemental hormones (e.g. recombinant bovine somatotropin or rbST). Even soy 'milk' contains plant-based hormones.

Secondly, milk in the US is fortified with vitamin D to (very successfully) prevent rickets. Vitamin D is a steroid hormone that is absorbed in the small intestine.

Thirdly, there is no evidence to show that cows given supplemental rbST have an increased concentration of either naturally-occurring or recombinant bST in milk. rbST was approved by the FDA in 1993 as being safe both for animal use and for human consumption of the resulting dairy products, and has been available for producers to use since 1994. rbST is a protein hormone and is therefore digested in the stomach, producing amino acids that are absorbed in the small intestine. This means that it has no biological activity in humans. Furthermore, there is no test available to show whether bST in milk originated from the cow herself or from supplementation, and the levels of bST in milk samples is often too low to detect in the lab.

Finally, I refer you to a recent study by Vicini et al. (2008, Journal of the American Dietetic Association, vol 108) that investigated the nutritional and hormonal composition of milk from the 48 contiguous states labeled as conventional, rbST-free or organically produced. All milks sampled had similar nutritional contents (fat, protein, lactose etc) and both organic and conventional milks had the same bST content. Furthermore, estradiol contents were actually higher in organic and rbST-free milk than conventional milk.

Myth: Organic/rbST-free milk doesn't contain any hormones. BUSTED!

By Jude L. Capper

References: Vicini et al., 2008. JADA; 108: 1198-1203.

NEXT MYTH: Watch this space...

Sunday, November 23, 2008

Are dairy products bad for your health?

The American Medical Association and American Dietetic Association have both stated that saturated fat consumption leads to increased cholesterol levels and heart disease. Based on this, consumption of dairy products predisposes us to coronary heart disease.

Premature death from cardiovascular disease has fallen since the mid-1970s in the US and UK. However, saturated fatty acid intake has not changed. How can this be? We’ve been told that saturated fat consumption predisposes us to coronary heart disease (CHD).

The recommendations to reduce the amount of saturated fat consumptions are based on the relationship between dietary intake of saturated fat and their potential to increase cholesterol levels. But does saturated fat increase cholesterol? In a meta-analysis of 60 trials,saturated fat increased total cholesterol, LDL-cholesterol (the “bad” cholesterol) and HDL-cholesterol (the “good” cholesterol). However, the ratio of total cholesterol to HDL-cholesterol has been suggested to be one o f the best indicators of CHD risk; and this ratio was slightly elevated with saturated fat consumption. Thus, consumption of saturated fats increases the good cholesterol, which counteracts the bad cholesterol, resulting in no overall negative effect.

What about dairy products though?

Cow’s milk is 3 to 4% fat, which is 60% saturated fat, 25% cis-monounsaturated fat, 2% trans-monounsaturated fat, and the remainder is poly-unsaturated fat. The National Health and Nutrition Examination Survey (NHANES) looked at the effect of dairy consumption on blood lipids in adults. There was no effect of the number of servings of dairy products consumed per day (ranging from less than 1 to greater than 4.5) on total cholesterol, LDL-cholesterol (the “bad” cholesterol), HDL-cholesterol (the “good” cholesterol) or triglycerides. Additionally, in the meta-analysis mentioned above, cis-monounsaturated fat significantly decreased the ratio of total cholesterol to HDL-cholesterol, suggesting decreased CHD risk. All of the evidence shows that dairy products do not predispose us to heart disease.

Myth: Consumption of dairy products predisposes us to coronary heart disease. BUSTED!

By Robin R. Rastani

References: Mensink et al., 2003. Am. J. Clin. Nutr.; NHANES, 1999-2002.

NEXT MYTH: Organic milk doesn't contain hormones.... or does it?

Sunday, November 9, 2008

Should we all be vegans?

Activist groups like PETA often promote the message that we should all be vegan and that farm animals would be more healthy and happy if they were allowed to wander unfettered through sun-lit pastures rather than being farmed. Is this really the future that we want to see?

Ok. Let’s think about this from an animal welfare point-of-view. Leaving aside the increased risk of predation (coyotes killing sheep, foxes killing lambs, chickens as road-kill), there’s no doubt that animal health can be at risk in such an environment. Investigation of the recent avian flu outbreaks showed that the spread and prevalence of the disease was widespread among outdoor and backyard chicken flocks, with no disease found on farms where chickens were housed in barns. Allowing animals to wander free totally negates biosecurity, putting the entire US herd or flock at risk, especially when notifiable diseases such as avian flu or foot-and-mouth occur. While it’s nice to imagine ‘happy’ Holstein cows peacefully grazing lush spring pastures, what happens when that pasture is buried under 48 inches of snow, or is bare and brown after only 1 inch of rain has fallen in the past four months? More to the point, where’s this pasture going to come from? If a producer doesn’t need to use their land to produce animal feed, how long will it be before it’s covered with concrete and houses?

However, this brings me to my main point, the one that the idealistic vegans seem to miss: if we all went vegan tomorrow, there would be no farm animals. No cute little chickens for the kids to hand feed, no baby lambs to pet at farm days, no doe-eyed Jerseys for 4-H kids to raise and take care of… just a big pile of 9.2 million slaughtered dairy cows.

Welfare-friendly? I think not.

Myth..... BUSTED!

By Jude L. Capper

NEXT MYTH: The American Medical Association and American Dietetic Association have both stated that saturated fat consumption leads to increased cholesterol levels and heart disease. Does consumption of dairy products predispose us to heart disease?