Frequently Asked Questions (FAQ)

Question: I have heard that pathogenic bacteria can't grow in raw milk, but good bacteria can. In fact, I have heard that milk targets pathogens and kills them, leaving the good bacteria.

Answer: Many myths surrounding raw milk are out there, including this one. Milk doesn't know ‘good' bacteria from ‘bad' bacteria any more than you would by looking at them with the naked eye. Raw milk is essentially sterile in healthy cows. It's not contaminated until after it comes out of the cow, and that's what really matters as to whether it will contain ‘good' or ‘bad' bacteria. If the milk is contaminated with fecal matter, there will probably be pathogens in the milk at some level, along with other contaminants normally found in dairy-type environments. Fortunately, these other contaminants are found in much larger numbers than are pathogens, so they often will out-compete them.

Question: How do polysaccharides encourage the growth of good bacteria and not bad bacteria?

Answer: Polysaccharides are complex sugars. Examples of polysaccharides include starch, cellulose, and glycogen. Polysaccharides do not occur naturally in milk. The only sugar found in milk is lactose, which is a disaccharide (double sugar) made up of the monosaccharides (simple sugars) galactose and glucose. Bacteria, whether they're ‘good' or ‘bad' can use many different types of sugars as energy sources. For example, many of the culture organisms used to make yogurt or cheese are very good lactose fermenters, which makes them ideal organisms for this purpose. These organisms also create desirable flavors in the milk while they are growing. However, E. coli, a well known pathogen can also ferment lactose, for example.

Question: Aren't there more cases of food borne illness in pasteurized milk than in raw milk?

Answer: From 1990-2003, 153 outbreaks associated with consumption of milk or milk/dairy products affected 5,156 people. Of those, 53 (33%) of the outbreaks, which affected 1,440 people, resulted from consumption of raw milk or raw milk products. Fluid milk products were responsible for 14 (9%) of the outbreaks, with 389 illnesses. Other products (cheese, ice cream and other dairy products) caused 89 outbreaks with 3,327 cases (for many of these outbreaks, the pasteurization status of the products was not reported, and thus, is unknown.) In general outbreaks associated with raw milk consumption tend to be smaller in scale than those associated with pasteurized product consumption as raw milk products are usually available in relatively small quantities and products intended for human consumption cannot legally cross state lines, whereas pasteurized products are produced in greater volumes and often have a much wider distribution.

Milk production in 2009 totalled 189 billion pounds. Marketed milk (sold for processing into fluid milk/cheese/cultured products/ice cream or other dairy products)s totaled 188 billion pounds. Roughly 15-20% of this is used to produce fluid milk and the rest is used to make other dairy products. An estimated 1.01 billion pounds of milk were used on farms where produced. Calves were fed 89 percent of this milk, with the remainder consumed in producer households. (Source USDA, Milk Production, Disposition and Income-2009 Summary, Apr 2010). These numbers are typical of the average year. Therefore, in an average year, about 37 billion pounds are used to make pasteurized milk products and it's estimated that about 89 million pounds of the milk used on the farm was fed to calves, which leaves approximately 11 million pounds being consumed by producer households.

Question: I've heard that cows that produce milk that is conventionally pasteurized are kept in confinement, is that true of all pasteurized milk?

Answer: Cows are typically not ‘confined' to a small space. Many dairies have distinct areas for certain groups of cows; however, most cows in confinement are there for a reason. For example, cows that are being treated with antibiotics may be kept in a separate area from the regular milking herd to prevent their milk from entering the milk destined for a dairy plant. Freshening cows (those about to give birth) are sometimes kept separate so that the herdsman/farmer can watch them to ensure a healthy delivery. Opportunities for pasture exposure must be considered in relative terms. A pasture in the Northeast may be covered in snow for 4-5 months, during which cows cannot access pasture grass. Conversely, a pasture in Texas may be negatively affected by drought or intense heat, which results in the same consequence: no available grass. The most important issue in animal husbandry isn't whether cows have access to pasture, it's whether they are being treated humanely and have adequate food and water to sustain them. Access to a pasture with an inadequate supply of grass does them no good.

Question: Doesn't pasteurization destroy milk protein?

Answer: Pasteurization does denature some milk proteins. Protein denaturation is influenced by the length of time and amount of heat that is applied. Protein denaturation is commonly encountered in food preparation. To illustrate, when you heat ground beef, proteins are denatured, and the color changes. Further, chicken meat turns from its raw reddish color to white as heat is applied (cooked). The protein in milk, like the protein in meat, is still generally nutritionally available as a nutrient to the human body. Folacin uptake has been reported as less efficient in pasteurized milk because of folacin binding protein (FBP) denaturation .

Question: According to the FDA's definition of adulterated food, doesn't pasteurized milk fall into that category?

Answer: The FDA's definition of adulterated food is as follows:


SEC. 402. [342] A food shall be deemed to be adulterated—

(a)(1) if it bears or contains any poisonous or deleterious substance which may render it injurious to health; but in case the substance is not an added substance such food shall not be considered adulterated under this clause if the quantity of such substance in such food does not ordinarily render it injurious to health; or

(2)(A) if it bears or contains any added poisonous or added deleterious substance (other than one which is (i) a pesticide chemical in or on a raw agricultural commodity, (ii) a food additive, (iii) a color additive, or (iv) a new animal drug) which is unsafe within the meaning of section 406; or

(B) if it is a raw agricultural commodity and it bears or contains a pesticide chemical which is unsafe within the meaning of section 408(a); or

(C) if it is, or it bears or contains, any food additive which is unsafe within the meaning of section 409: Provided , That where a pesticide chemical has been used in or on a raw agricultural commodity in conformity with an exemption granted or a tolerance prescribed under section 408 and such raw agricultural commodity has been subjected to processing such as canning, cooking, freezing, dehydrating, or milling, the residue of such pesticide chemical remaining in or on such processed food shall, notwithstanding the provisions of sections 406 and 409, not be deemed unsafe if such residue in or on the raw agricultural commodity has been removed to the extent possible in good manufacturing practice and the concentration of such residue in the processed food when ready to eat is not greater than the tolerance prescribed for the raw agricultural commodity; or

(D) if it is, or it bears or contains, a new animal drug (or conversion product thereof) which is unsafe within the meaning of section 512; or

(3) if it consists in whole or in part of any filthy, putrid, or decomposed substance, or if it is otherwise unfit for food; or

(4) if it has been prepared, packed, or held under insanitary conditions whereby it may have become contaminated with filth, or whereby it may have been rendered injurious to health; or

(5) if it is, in whole or in part, the product of a diseased animal or of an animal which has died otherwise than by slaughter; or

(6) if its container is composed, in whole or in part, of any poisonous or deleterious substance which may render the contents injurious to health; or

(7) if it has been intentionally subjected to radiation, unless the use of the radiation was in conformity with a regulation or exemption in effect pursuant to section 409.

(b)(1) If any valuable constituent has been in whole or in part omitted or abstracted there from; or (2) if any substance has been substituted wholly or in part therefore; or (3) if damage or inferiority has been concealed in any manner; or (4) if any substance has been added thereto or mixed or packed therewith so as to increase its bulk or weight, or reduce its quality or strength, or make it appear better or of greater value than it is.

(c) If it is, or it bears or contains, a color additive which is unsafe within the meaning of section 706(a).

Pasteurized milk is not considered by definition to be adulterated food because of the pasteurization process. If post-pasteurization contamination allowed for the introduction of pathogens, or if the product became dangerous to a consumer in some manner, the product would be considered adulterated.

Question: I've heard that if I drink raw milk long enough I will become immune to the "bad" bacteria in it, this immunity will also help me fight off foodborne illness from other sources. Doesn't that mean that if I give my children raw milk from infancy, they will get sick much less often?

Answer: Friedrich Nietzsche said “that which does not kill us makes us stronger”, which can be true of a body's immune response following exposure to foreign materials including bacterial pathogens. Exposure to a low dose of pathogens by one individual may result in no illness, but exposure to the same dose for another who is immuno-compromised, or with an undeveloped immune system may result in illness or death. A recent study shows that approximately 13% of farm bulk tanks contain pathogens of one sort or another (Jayarao et al, Journal of Dairy Science 89: 2451-2458). While a healthy 30 year old person may be able to fight off a dose of E. coli or Listeria infection, a 4 year old child or an elderly person may not. Further, pregnant women's fetuses are at high risk of listeriosis infection, which may result in abortion, since Listeria monocytogenes is an invasive pathogen (able to penetrate cells, thereby gaining access to the placenta and causing infection of the fetus).

Question: If cows are kept on pasture then would they even have need of antibiotics? Is the milk coming from those cows safer?

Answer: Regardless of the management system in place, cows can develop infections that require attention. For example cows kept on pasture can develop mastitis (infection of the udder) and other illnesses. Infections in cows are sometimes painful and may require antibiotic therapy. Udder infections can be caused by many different things. Dirty farm/barnyard conditions, poor milking practices, poor sanitation of milking equipment, teat or duct injury, to name a few. Cows in any environment are exposed to opportunistic mastitis pathogens. The milk from cows routinely kept on pasture is no safer than milk from housed or ‘barnyard' cows. The main strategies for producing safe milk are good animal husbandry practices (minimizing conditions that lead to mastitis infections), quality milking equipment and exceptional sanitation practices while milking and handling/storing the milk to minimize contamination. More good information on mastitis and microorganisms that cause it can be found at .

Question: Why is it calves never get sick from drinking raw milk?

Answer: Calves do sometimes get sick when they drink raw milk. As in humans, pathogenic bacteria can be transferred through the milk to calves. Also it is possible for the calves to have severe scours (diarrhea) from raw milk, but it is probably not related directly to the raw milk but to the cleanliness and sanitation of the system/equipment that is feeding them (since we know raw milk is essentially sterile when taken properly from a healthy cow). The calf has an excellent adaptive immune response, especially if given adequate colostrum, and as long as we give the calf adequate nutrients above maintenance, it can fight off many diseases or illnesses.

Calves on dairy farms are often fed milk replacer. Some of the more progressive farms feed milk to their calves after a heat treatment step (similar to pasteurization to kill pathogens). A small study done and published appeared in Pro-Dairy's “The Manager” (June 2004), written by Bill Stone, DVM. In the study, a farm installed a pasteurization system, and fed waste milk pasteurized to calves. They note a 1.3% mortality rate and an average of 1.65 lb weight gain per day for the first 8 weeks.

A review of data by Sandra Godden, DVM and published in 2003 reports the following:

Raw vs. Pasteurized Waste Milk – Health and Performance of CA dairy calves.

In a study of 300 calves on a large California dairy calves fed pasteurized colostrum and milk had fewer sick days, lower mortality rates, lower costs for health expenditures, higher weights at weaning, and a higher gross margin ($8.41/calf) per calf, as compared to calves fed nonpasteurized waste milk (Jamaluddin et al. 1996).

Milk Replacer vs. Pasteurized Waste Milk – Health and Performance of MN dairy calves.

A recent 10-month field study of 439 dairy calves raised by a professional heifer grower in Minnesota systematically assigned calves, on arrival, to one of two feeding programs: 1) treatment group = pasteurized waste milk (n = 217) or 2) control group = traditional 20:20 milk replacer (n = 222). Waste milk from just fresh (transition milk) and antibiotic-treated cows was pasteurized before each feeding using a commercial batch pasteurizer (Dairytech Inc., Windsor , Colorado ). Calves fed pasteurized waste milk gained significantly more weight and were heavier at weaning (58.8 lbs gain; 147.3 lbs at weaning) than calves fed milk replacer (44.3 lbs gain; 134.0 lbs at weaning). Average daily gain (ADG) was significantly greater in calves fed pasteurized waste milk (1.04 lbs/day) vs. calves fed milk replacer (0.76 lbs/day). Preweaning mortality rates were significantly lower for calves fed pasteurized waste milk (2.3%) than for calves fed milk replacer (11.6%). Preweaning health and performance was significantly better in calves fed pasteurized waste milk as compared to calves fed a traditional 20:20 milk replacer feeding program.

The FDA has also published a "frequently asked questions" page regarding raw milk.