Thursday, February 10, 2011

Steph’s Science Corner: The Raw Milk Debate

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Glass of milkPublic health has been a contentious topic in society since the era of mankind began. Issues such as what we eat, how we treat and prevent disease, and how to increase our lifespan take up more of our attention and occupy more of our news than nearly any other subject of public interest. It is as hotly contested, as violently inflammatory, and as cut-throat as any political, moral, or religious debate in today’s culture.

One of the most divisive topics in current public discourse concerns the body’s most essential need: food. Because eating is a staple of our existence, it ties in moral judgment, social responsibility, and personal freedom. Making the matter even more contentious, food science suffers from the weakness of being not just a science, but interdisciplinary. That means that not only does it bear the doubts, shortcomings, and restrictions of scientific investigation, but it covers a spread of experts from many different fields with vastly different priorities including biology, medicine, and agriculture.

Recently leading the charge in the battlefield of food science is the raw movement – the idea that cooking certain foods compromises their value. The argument asserts that heating destroys naturally-occurring nutrients, eliminating the good stuff with the bad. With vegetables, the matter is straightforward. Eating raw plant matter, if washed, is safe and often preferable. Animal by-products, however, are far more dangerous. Advocates have recently been emerging that reject the traditional treatment processes for milk (the kind we typically buy in the grocery store), preferring instead to drink – and hotly defending the advantages of – raw milk. In other words, milk that comes straight from the cow’s udder.

cow udderThis is a rather loaded issue. The FDA and other federal health organizations have come out strongly against drinking untreated milk, which they argue is a public health risk, while holistic practitioners and small dairy farmers are advocating fervently that it is safe, healthier than treated milk, and that they have a right to control what food they ingest. The legality of its commercial sale is determined by individual states, currently illegal in twenty-three. In this week’s segment, I will explain the pasteurization and homogenization processes, and then I will introduce some of the arguments made by each side of this issue in an attempt to analyze their scientific (as well as briefly visiting their legal, and moral) merit. It will be hard to mask my opinion behind a thin veil of objectivity, and I will not try to. However, I will not dismiss the power of fervor, or the deeply personal attachment that many people have to their beliefs even in the face of undisputed proof, which in this debate is quite limited. As you read this, know that it is not my goal to throw my voice into the raw milk debate, but rather to educate readers about its roots as it begins to take hold in our upcoming cultural stage.

Homogenization

Suspension_Emulsion_2b Notice that the key root of this word is the prefix used to describe things that are uniform or distributed evenly. By definition, homogenizing it is the blending of two things that don’t mix together, like oil in water, in a way that forces them to disperse in a mixture called a suspension or an emulsion. Milk, as it comes straight from a lactating mother, is a watery suspension of fats, proteins, vitamins and minerals. In raw milk taken straight from the production glands, the fat (or the cream) separates quickly from the water and collects on a surface layer. In this way, it is possible to “skim off” the fat, which is then used for cream, butter, and cheese, and the removal of this layer is how we can reduce the fat content of our milk.

Homogenization forces the milk through very small holes at a high pressure, forcing the large fatty globules to break into tiny droplets, which stay separated more easily. That’s why, when you buy whole milk at the store, you don’t have to shake it before you drink it.

Pasteurization – the Frenchman and his wine

Pasteur Scientists didn’t understand that illness was caused by tiny organisms until the 18th and 19th centuries. One of the contributors to germ theory was a French chemist named Louis Pasteur, regarded as one of the three founders of microbiology. His work included contributions to antiseptics in surgery, the reduction of mortality rates in puerperal fever, saving silkworms from a devastating epidemic, and the development of vaccines for rabies and anthrax. But his earliest work was the discovery that food spoilage occurs because of the rapid growth of micro-organisms.

From here, he was quick to discover that brief exposure times to high-temperature environments killed most of the bacteria and molds within a liquid, and that this slowed the spoiling rate significantly. He originally designed what became known as pasteurization to keep wine from going sour (because what else do the French really care about?), but most popularly, it was used to increase the shelf-life of milk. Put simply, pasteurization is the process of heating something to a specific temperature for a certain length of time and then quickly cooling it. This temperature is typically below boiling since, at high temperatures, the main protein found in milk will irreversibly aggregate – in other words, curdle.

pasteurization process diagramIn order for milk to be labeled as pasteurized, it must undergo “High Temperature/Short Time” treatment (HTST). In the “continuous method,” milk is pumped through long thin pipes that are submerged in 160-degree water for 15-20 seconds, and then cooled in a matter of seconds. Another option, called the batch method, is just what it sounds like. The milk is collected into a large vat and constantly stirred, treating one bulk amount at a time.

These standards are specific to the type of milk product, so fluid milk will have different requirements than cream or milk intended for cheese making. These values are calculated to kill 99.999% of viable micro-organisms while still leaving as much of the taste and nutritional value as possible intact. It is still very much possible for bacteria to enter into milk after it has undergone pasteurization. For this reason, it must be kept cold (slowing down bacteria growth) and its exposure to air and contaminated surfaces must be minimized after treatment.

The nutritional values of milk and its history as a dietary staple

As mentioned above, milk is an emulsion of fat and water. The fatty portion contains the vitamins A, D, E, and K. The water portion contains small amounts of water-soluble proteins (called whey proteins), as well as a much larger quantity of caseins -- the primary milk protein. This portion also contains the milk sugar known as lactose, as well as water-soluble vitamins and minerals such as vitamin C and calcium.

sardinesSome of the vitamins and minerals that we associate with milk are not actually abundant in it, naturally. Most of our milk is fortified with extra nutrients, the most well-known being vitamin D. It is found in fatty fish species such as catfish, sardines, and eel, but it is unique because it is the only vitamin that it is produced naturally by our skin upon exposure to sunlight. While we suspect that it may have a number of important health benefits, one of its primary functions is to help the body absorb calcium, which is essential to bone health.

Milk is the essential form of nutrition for infants of nearly all mammals. Each animal produces its own biochemically distinct type of milk that is evolutionarily designed to meet the particular needs of its young. Humans are the only animals that consume milk past infancy, specifically milk that is meant for the young of another species, despite the fact that many of us show at least some intolerance to lactose. Our bodies are equipped with unique enzymes (self-produced catalysts that help us break down food energy) that specifically aid in the digestion of lactose – called lactase – and they reach their highest levels in our bodies just after birth, declining as we age.

Regulations on the milk we consume

The food and drug administration does not allow milk to be sold for consumption unless it meets Grade A standards. A farm that sells Grade A milk must be inspected every six months and maintained with strict standards of hygiene and chemical safety. The milk must stay within a certain temperature at all times, and it must undergo tests that prove that it has fewer than the maximum safe level of micro-organisms present. Specifically, the white blood cell count (a measurement of potential infection in cows) must fall below 750,000 cells per mL, and the bacterial count may not exceed 100,000 per mL.

These same regulations apply to all milk-sellers, including large-scale commercial farms, small dairy farms, and farms that distribute raw milk. This, therefore, leads to the argument that if raw milk was sold commercially, it would have to adhere to the exact same standards as pasteurized milk, regardless of how these levels were achieved.

The benefits of pasteurization

Pasteurization was considered one of the greatest public-health success stories of the 20th century, becoming universal in 1950. It expanded the range of families that could acquire milk safely, and drastically reduced the instance of food-borne illness. Most public health professionals are adamantly in support of it. It is recommended by the Center for Disease Control, the FDA, and the American Academy of Pediatrics.

Strep Some of the common microbes found in milk may include E. coli, salmonella, listeria, bovine tuberculosis, streptococcus, parasites such as Giardia, norovirus, and organisms that could lead to Guillain-Barré syndrome. Milk can become contaminated through intestinal bacteria that is naturally present in tolerable quantities to the animal, but is dangerous to humans if allowed to multiply. It can also come from the exterior of the udder when mud or fecal matter is picked up from the ground.

Currently, the U.S. has no federal law against drinking raw milk, however the FDA has banned its interstate sale, leaving commerce within borders up to individual state mandate. People have attempted to circumvent the law in some of these states by paying for a portion of a cow’s day-to-day costs in order to collect milk, but Wisconsin banned this cow-sharing program after 75 people became infected with Campylobacter jejuni bacteria in 2001.

The pro-raw milk argument, potential health benefits and personal ideals

Obviously, people drank raw milk for thousands of years. In this country it was commonly limited to rural families owning one or two cows for private use, where it received limited attention. But it has recently caught on with people in search of healthier alternatives, with supporters claiming that it not only tastes better, but has many proven health benefits that are lost in pasteurization.

Raw milk enthusiasts tout its merits in two areas. First, they say that “helpful bacteria” which aids in digestion is plentiful in raw milk, but that it is killed off by the heat exposure. Secondly, they suggest that many of milk’s natural vitamins, minerals, and enzymes that may aid in digestion (specifically, the digestion of milk, eliminating lactose-intolerance), are destroyed by pasteurization. Some people go as far as to say that raw milk is a miracle-cure which prompts the body’s self-healing abilities, enhancing the immune system, curing asthma and allergies, and repairing damage to the gastro-intestinal tract.

cowsSmall dairy farmers argue that pasteurization was necessary because of unsanitary conditions maintained by large urban dairies, which allows sick and infected animals to be diluted in the herd. They accuse large dairy farms of being afraid to lose business. Raw milk, they say, is cleaner because of their environmentally-responsible farming practice.

Most controversially, raw-milk enthusiasts describe milk’s ability to “protect itself.” They say that competition offered by good bacteria limits bad bacteria, or that lactic acid provides a harsh atmosphere for growth. However only grass-fed animals have the correct nutrient balance to achieve these ideal conditions, they say. This claim is harshly rejected as untrue by food safety advocates.

The raw milk rebuttal, legality and public safety

The CDC and the FDA have not stood idly by as this trend expanded its reach, especially after they were targeted by legal action. They have started educational websites, responding to the claim that raw milk protects itself by identifying outbreaks of illness that were traced back to cows in organic raw-milk farms. They tout scientific evidence collected by non-partisan, public-interest groups that show that the long and short-term health benefits of milk are not significantly altered by pasteurization, and that the quantities of vitamins lost are small compared to the gain in public safety. For example, one vitamin often advertised as lost is C, but milk is not a major source of vitamin C to begin with. The FDA has found no reliable scientific evidence that accurately supports the claims made by raw-milk supporters about its curative properties.

Elevated levels of discourse and opinions running hot

There is a lot of armed, defensive discourse taking place on both sides. The FDA seems to be determined to stop the raw-milk movement from taking hold by convincing the population of its sweeping risks. Raw-milk supporters respond by minimizing these risks in comparison with other food-related illnesses that come from foods the FDA pronounced safe. They accuse the FDA of banding together in an evil conspiracy – sometimes to keep the big-business dairy farms in power, sometimes saying that their wonder-cure threatens a health-care industry that depends on keeping people sick.

There is also the debate over personal freedoms and legal rights. Advocates say that they should have sole jurisdiction over their bodies and their consumption, and the FDA has responded by pointing out that there is no such right written into the law, and that it exists to protect people from communicable diseases and widespread outbreak. They say that because many of the pathogens in raw milk are actually communicable (rather than just simple food-poisoning), it’s a risk to the public.

My thoughts

Before researching this post, my feelings were clear. Pasteurization was a miracle when it was first invented. I also feel a little bit odd about the fact that we drink milk when no other animal on this breastfeeding statueplanet does. And why cow milk? When we imagine drinking human milk in our adult life -- the kind we’re biochemically suited to -- most of us cringe. I can’t find many well-conducted studies to support the claims that raw milk is a miracle cure (other than anecdotal evidence), yet I believe in the statistical data and DNA tests that trace unsafe outbreaks. I am also inclined to believe the argument that we produce our own enzymes, and that bovine-specific enzymes aren’t really meant for us. I thought that raw milk was slightly silly at best, unsafe and irresponsible at worst.

I was also not impressed by the combative, conspiracy-riddled language of these websites that I investigated, on both sides. I found it annoying that big-bad government organizations were turned into idols of pure evil. They’re just people doing a public service. Likely they all have families and children, and I can assure you that if they knew of a way to live forever, they would be doing so. No one wants our children sick and dying. That just doesn’t happen on purpose.

As I’m disgusted by that type of behavior, I also wonder if the FDA isn’t overreacting. I’m pretty sure my farm-living father had a cow growing up, and drank its milk for years without any problems. Sometimes I wonder...would drinking raw milk help improve my sensitive digestive system? Or keep me from getting so many colds? I can see what tempts people into trying it. It probably is mostly safe, just like eating anything is mostly safe. We trust other people – whether its the FDA or the farmer down the street – to protect us.

Whatever your opinion, I will say this: the food debate is a broiler of strong emotions, absolutes, and incendiary dialogue. We turn our noses down at the choices of others, as if our organic foods make us superior. We call each other nasty names meant to minimize the admirable purpose of holding our food suppliers accountable. All of us want the same things – to be healthy and happy without spending too much money. In an age where we’re questioning our political rhetoric, I think it’s also important to tone down our food rhetoric. It’s just milk. Do your own research and leave your mind open.

But then I imagine a cow, covered in mud, lying down in a pile of poop, right in the udder. And I think to myself...maybe not.

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