It's the nature of cow's milk yogurt as a dairy food that makes it controversial. There can be many healthful aspects of cow's milk yogurt, especially when certified organic and obtained from grass-fed dairy cows. Yet, even in these optimal circumstances, yogurt remains controversial.

Three of the most controversial aspects of yogurt are (1) a disproportional number of adverse reactions to yogurt in comparison to other commonly eaten foods; (2) lack of regulatory standards needed to assure a natural lifestyle for dairy cows whose milk is needed to produce yogurt; and (3) potential contribution of large-scale yogurt production to excess greenhouse gas emissions and global warming.

Adverse Reactions to Yogurt

The vast majority of yogurt consumed in the U.S. is made from cow's milk, and cow's milk is listed by the Centers for Disease Control as one of the eight food types most closely associated with food allergy in the U.S. These eight food types are (1) wheat, (2) cow's milk, (3) hen's eggs, (4) fish, (5) crustacean shellfish (including shrimp, prawns, lobster and crab); (6) tree nuts (including cashews, almonds, walnuts, pecans, pistachios, Brazil nuts, hazelnuts and chestnuts); (7) peanuts; and (8) soy foods.

Processed foods containing yogurt (for example, yogurt covered pretzels or raisins) must be labeled as containing a potential allergen in the same way as foods containing cow's milk itself. In research studies, however, there is less documentation of allergic reaction to yogurt than to cow's milk in the U.S. This difference makes sense to us, for one basic reason: most yogurts consumed in the U.S. have been fermented with the help of live bacterial cultures, and this fermentation helps break down some of the proteins contained in cow's milk and lower the chances of an allergic reaction. The type of allergic reaction we are describing here involves the body's immune system and a response to specific proteins found in cow's milk. Some persons who are unable to consume cow's milk find that certain yogurts do not trigger the same type of allergic response by their immune system. This difference may be real and related to the fermentation process involved with the production of most yogurts. Still, many individuals do experience allergic reaction to yogurt and avoid it for this reason.

Yogurt and Lactose Intolerance

A second type of adverse reaction to yogurt involves the presence of lactose (milk sugar) in this food. People differ in their reaction to lactose, including the lactose found in yogurt. Some people experience digestive problems after consuming very small amounts of lactose. Others can tolerate very small amounts. Since yogurts can vary significantly in the amount of lactose they contain, it's difficult to predict how a person will react to any specific yogurt. However, as a general rule, fermented yogurts typically contain far less lactose than the cow's milk from which they are made. In 4 ounces of whole cow's milk, you will typically get 5-6 grams of total sugar, mostly consisting of lactose. Yet in 4 ounces of whole milk yogurt that has been fermented with the help of starter bacteria, you are likely to get only 3 grams of lactose. The reason for this decreased amount of lactose in yogurt versus cow's milk involves the use of lactic acid bacteria (LAB) to ferment the milk. While the LAB are fermenting the milk, they are also converting lactose into lactic acid and lowering lactose levels in the yogurt. For some individuals, the lactose level may become low enough to tolerate, even if cow's milk itself cannot be tolerated. For others, yogurt is still best avoided due to this type of adverse reaction.

Lack of regulatory standards to assure a natural lifestyle for dairy cows

A second aspect of the yogurt controversy involves the lifestyle of dairy cows needed to produce yogurt's basic ingredient: milk. There are approximately 9.3 million dairy cows in the U.S. (mostly black and white Holsteins) and they produce about 196 billion pounds of milk each year. A significant amount of this milk is used to produce yogurt, and yogurt is rising in prominence as a dairy product. Given these circumstances, it's easy to understand how the lifestyle of dairy cows might be a special concern for individuals who think about yogurt and its place not only in their meal plan but also in the food supply.

In the U.S. and in many other countries, the role of dairy cows in our cultures has changed dramatically over the centuries. Instead of a small number of cows being cared for by humans living on small family farms, or a small number of cows being herded by nomadic cultures who traveled to find pasture land and water for their herds, dairy production in the United States now involves nine million dairy cows who produce about 20,000 pounds of milk each year or 180 trillion pounds total. This level of production is not possible without certain constraints on the lifestyle of the cattle. Maximal milk production is difficult if cows are left to graze in pasture year-round. Maximal milk production is also difficult if cows are only milked during the first trimester of pregnancy, rather than continuously throughout the second and third trimesters. Artificial insemination is often necessary to allow for near year-round milk production. Maximal production also tends to require milking at least twice per day. All of these practices impact the life of dairy cows.

One of the most controversial practices impacting the life of dairy cows is use of rbGH. Short for "recombinant bovine growth hormone," rbGH is estimated to be used in the raising of approximately 15-20% of U.S. dairy cows. You'll also see this hormone called rbST (recombinant bovine somatotropin). Originally developed by Monsanto and now produced by Elanco (a company that acquired rights to the synthetic hormone from Monsanto in 2008), rbGH is sold under the brand name Posilac (TM) and it is one of the largest dairy animal pharmaceutical products sold in the U.S. Use of rbGH in dairy cows in the U.S. began in the mid-1990's as a way of increasing milk production. From a physiological perspective, rbGH is part of a complicated network of hormones and hormone-like substances that are required for growth and proper differentiation of cells.

An especially important part of this network is a polypeptide (small protein-like molecule) called insulin-like growth factor 1, or IGF-1. In humans, elevated blood levels of IGF-1 are associated with increased risk of certain cancers, especially breast cancer in women and prostate cancer in men. Cows injected with rbGH would, of course, be expected to have elevated amounts of rbGH in their bodies. In addition, however, cows injected with rbGH would be expected to have higher levels of IGF-1 as well. A question raised by many scientists is whether humans regularly consuming milk from rbGH-injected dairy cows are at increased risk for IGF-1 exposure and IGF-1 associated cancers. We have not seen any large-scale human study that has determined regular consumption of milk from rbGH-injected cows to be a risk factor for cancer. In fact, we've found indexed-journal reviews in this area that report no evidence for this association. Still, the connection between excessive exposure to growth hormone, IGF-1, and increased cancer risk makes logical sense to us, and it is an issue that seems worthy of concern.

In the U.S., the only regulatory standards prohibiting use of rbGH in dairy products involve certified organic dairy products. Its use is strictly prohibited in certified organic foods. In other countriesâ€"including countries like Canada, Australia, New Zealand, Japan, and all countries belonging to the European Union (27 countries, including the United Kingdom, France, Spain, Italy, Germany, Greece, Hungary, Poland, Norway, Sweden and Denmark)—regulations have banned rbGH in all dairy products.

One of the reasons we recommend purchase of 100% grass-fed yogurt involves the better lifestyle that 100% grass feeding affords dairy cows. The vast majority of dairy cows in the U.S. are raised in Intensive Production Systems (IPSs) that provide little access to fresh pasture. IPSs generally involve confinement facilities consisting of barns, feedlots, stalls, pens, feeding alleys, and sorting alleys. In place of a fresh pasture diet, IPSs typically rely on total mixed rations (TMRs) and concentrates made from grains, fermented grains, hays, fermented hays, soymeal, soybean hulls, citrus pulp, linseed meal, cottonseed meal, and other ingredients. TMRs and concentrates can result in digestive problems for the cows including bloat and other problems.

U.S. governmental regulatory agencies do not currently provide strict dietary or pasture standards for dairy cows. For example, certified organic cow's milk does not provide strict regulations for pasture feeding. Certified organic cow's milk may be obtained from cows who only had access to pasture on 120 days of the year and who only obtained 30% of their food from pasture on those days. Similarly, USDA certification for grass-fed dairy products requires continuous access to pasture during the growing season but not during other parts of the year. USDA grass-fed animals are required to consume grasses and forages as their food source year-round, although this rule does allow for the inclusion of cereal grain products like corn if provided in the early (vegetative and pre-seed state) state, as well as for silage and vitamin/mineral supplements.

U.S. governmental regulatory agencies do not currently provide strict dietary or pasture standards for dairy cows. For example, certified organic yogurt does not provide strict regulations for pasture feeding. Certified organic yogurt may be obtained from cows who only had access to pasture on 120 days of the year and who only obtained 30% of their food from pasture on those days. Similarly, USDA certification for grass-fed beef requires continuous access to pasture during the growing season but not during other parts of the year. While it is true that USDA grass-fed animals are required to consume grasses and forages as their food source year-round, they can still be denied access to pasture and fresh grasses during the non-growing season, provided that they continue to consume grasses and forage in some form (for example, in dried or fermented form). USDA grass-fed standards also allow pasture forage to include cereal grain plants like corn, but only if those plants are in the early stages of development before forming seeds.

Requirements for pasture access and grass-based diets are stricter with third-party certification by the Food Alliance (FA) and the American Grassfed Association (AGA). These stricter requirements, which help improve the lifestyle of the cow, are one of the reasons that we recommend purchase of grass-fed yogurt that has been certified by one or both of these organizations.

Potential contribution of yogurt production to excess greenhouse gas emissions and global warming

According to the Intergovernmental Panel on Climate Change (http://www.ipcc.ch/), the average surface temperature of the earth has increased by 1.3 degrees Fahrenheit over the past 100 years. This increase in temperature is commonly referred to as "global warming," and it's due to excessive accumulation of certain gases in the atmosphere surrounding the earth. These gases are called "greenhouse gases" because they help turn the earth into a greenhouse that is warm enough for living things to survive. Greenhouse gas is a good thing. Without them, the earth would still be frozen and unable to support life. However, too many greenhouse gases create a blanket around the earth that is too thick and traps too much of the sun's heat. If too much heat is trapped, the earth's ecosystem balances get disrupted, including the flow of rivers, patterns of wind, and animal habitats.

On a global basis, about 10-15% of unwanted increases in greenhouse gases (GHGs) come from agriculture. Even though there is unwanted release of carbon dioxide (a key greenhouse gas) into the atmosphere due to the use of industrial farm equipment that requires the use of gasoline, oil, or natural gas, carbon dioxide is not the primary greenhouse gas of concern in agriculture. That distinction goes to two other greenhouse gases: methane, which is released into the atmosphere from manure (and primarily cow manure), and nitrous oxide, which is released into the atmosphere following use of nitrogen-containing fertilizers used in the cultivation of feed crops for animals (and primarily cows). So there are some direct links between the phenomenon of global warming and the raising of dairy cows in Intensive Production Systems that involve increased reliance on nitrogen-containing fertilizers and feed concentrates that increase nutrient intake, growth, and as a by-product of increased growth and consumption, manure. These links between global warming and the raising of dairy cows naturally extend to the production of yogurt.

A more natural lifestyle for dairy cows involving 100% grass feeding can lessen both of these problems. Less focus on intensive production can mean less use of nitrogen-containing fertilizer, as well as less concentrated dietary intake resulting in less manure. These favorable environmental consequences of 100% grass feeding are another reason that we recommend selection of 100% grass-fed yogurt.

It's also worth noting that 100% grass feeding typically means more emphasis on the existence of pasture land within dairy farms. This increased focused on pasture land brings with it more cultivation of food crops and cover crops. Increased crop cultivation, in turn, means increased capture of carbon dioxide by the crops and less lease of carbon dioxide into the atmosphere. (Plants take in carbon dioxide and release oxygen into the air.) Some scientists have estimated that widespread use of cover crops and planted pasture land in global agriculture could turn global agriculture into an industry that actually helps reduce the amount of carbon dioxide in the atmosphere rather than increasing it.

Summary

While we believe that modest servings of whole milk yogurt from 100%-grass fed cows can help to lessen some of the concerns about this food, we understand how controversial it remains and we respect the decision of many individuals to avoid it in their meal plan. We do not consider intake of whole milk, grass-fed yogurt to be mandatory for anyone. At the same time, however, we recognize that some people do well when including it in their diet, and we want to provide as accurate information as we can about this controversial food.