Milk is a nutritious food that provides protein, vitamins, minerals and fatty acids.
Prior to the introduction of pasteurization in the early- to mid-1900s, all milk was consumed raw in its natural, unprocessed state.
With the growing popularity of natural, local, farm-sourced foods and the perception that raw milk is healthier, its consumption is increasing ().
Raw milk advocates argue that it has superior health and nutritional benefits and that pasteurization eliminates these advantages.
However, government and health experts disagree and advise against consuming it.
This article looks at the evidence to determine the benefits and dangers of drinking raw milk.
Raw milk has not been pasteurized or homogenized.
It primarily comes from cows but also goats, sheep, buffalos or even camels.
It can be used to make a variety of products, including cheese, yogurt and ice cream.
An estimated 3.4% of Americans drink raw milk regularly (2).
The Pasteurization Process
Pasteurization involves heating milk to kill bacteria, yeasts and molds. The process also increases the product’s shelf life (3, ).
The most common method — used all over the world, including the US, UK, Australia and Canada — involves heating raw milk to 161.6°F (72°C) for 15–40 seconds ().
Ultra-heat treatment (UHT) heats milk to 280°F (138°C) for at least 2 seconds. This milk is, for example, consumed in some European countries ().
The main method keeps milk fresh for 2–3 weeks, while the UHT method extends the shelf life up to 9 months.
Pasteurized milk is often also homogenized, a process of applying extreme pressure to disperse the fatty acids more evenly, improving appearance and taste.
Summary Raw milk has not been pasteurized or homogenized. Pasteurization heats milk to kill bacteria and increases shelf life.
Raw milk advocates argue that it’s a complete, natural food containing more amino acids, antimicrobials, vitamins, minerals and fatty acids than pasteurized milk.
They also claim that it’s a better choice for those with lactose intolerance, asthma, autoimmune and allergic conditions.
Pasteurization was first introduced in response to an epidemic of bovine (cow) tuberculosis in the US and Europe in the early 1900s. An estimated 65,000 people died over a 25-year period from contaminated dairy ().
Some raw milk advocates argue that many of the harmful bacteria destroyed by pasteurization, such as tuberculosis, are no longer an issue and that pasteurization no longer serves a purpose.
Furthermore, they claim that the heating process during pasteurization reduces the overall nutrition and health benefits of milk.
However, most of these claims are not backed up by science.
Claim 1: Pasteurized Milk Has Fewer Nutrients
An extensive meta-analysis of 40 studies found only minor losses of the water-soluble vitamins B1, B6, B9, B12 and C. Considering the already low levels of these nutrients in milk, these losses were insignificant ().
What’s more, they’re easily made up elsewhere in your diet, as these vitamins are widespread and found in many fruits, vegetables, whole grains and — in the case of vitamin B12 — animal proteins.
Levels of the fat-soluble vitamins A, D, E and K also minimally decrease during pasteurization (8).
Claim 2: Pasteurizing Milk Reduces Fatty Acids
In one study, 12 samples of cow’s milk were collected from a single dairy factory and divided into raw, pasteurized and UHT-treated. Comparison between the three groups showed no significant differences in major nutrients or fatty acids (14).
Claim 3: Pasteurizing Milk Destroys Proteins
One cup (240 ml) of pasteurized milk packs 7.9 grams of protein (12).
Pasteurizing milk does not reduce casein levels, as this type of protein is heat stable (, 8).
While whey protein is more susceptible to heat damage, pasteurization appears to have minimal impact on its digestibility and nutritional composition (, 8).
One study in 25 healthy people drinking either raw, pasteurized or UHT milk for a week found that the proteins from pasteurized milk had the same biological activity in the body as raw milk proteins ().
Interestingly, milk exposed to ultra-high temperatures (284°F or 140°C for 5 seconds) increased protein nitrogen uptake by around 8%, meaning that the protein was better used by the body ().
Claim 4: Raw Milk Protects Against Allergies and Asthma
A milk protein allergy occurs in 2–3% of children living in developed countries during their first 12 months — 80–90% of cases resolve spontaneously by age three ().
A hospital study in five children with diagnosed cow’s milk allergy found that pasteurized, homogenized and raw milk caused similar allergic responses ().
That being said, raw milk has been associated with a reduced risk of childhood asthma, eczema and allergies (, , , ).
One study in 8,334 school-aged children living on farms linked raw milk consumption with a 41% lower risk of asthma, 26% lower risk of allergy and 41% lower risk of hay fever ().
Another study in 1,700 healthy people found that drinking raw milk in the first year of life was associated with a 54% reduction in allergies and 49% reduction in asthma, regardless of whether participants lived on a farm or not ().
However, it’s important to note that these studies show an associated risk reduction, not necessarily a direct correlation.
Increased exposure to microbes within farming environments has also been associated with a reduced risk of asthma and allergies, which may account for some of these results (, , , ).
Claim 5: Raw Milk Is Better for People With Lactose Intolerance
Lactose is a milk sugar. It’s digested by the enzyme lactase, which is produced in your small intestines.
Some people don’t make enough lactase, leaving undigested lactose to ferment in the bowel. This causes abdominal bloating, cramps and diarrhea.
Raw and pasteurized milk contain similar amounts of lactose (14, ).
However, raw milk contains the lactase-producing bacteria Lactobacillus, which is destroyed during pasteurization. This should, theoretically, improve lactose digestion in raw milk drinkers ().
However, in a blind study, 16 adults with self-reported lactose intolerance drank raw, pasteurized or soy milk for three 8-day periods in randomized order, separated by 1-week washout periods.
No differences were found in digestive symptoms between raw and pasteurized milk ().
Claim 6: Raw Milk Contains More Antimicrobials
Milk is rich in antimicrobials, including lactoferrin, immunoglobulin, lysozyme, lactoperoxidase, bacteriocins, oligosaccharides and xanthine oxidase. They help control harmful microbes and delay milk spoilage ().
Their activity is reduced when milk is refrigerated, regardless of whether it’s raw or pasteurized.
Pasteurizing milk reduces lactoperoxidase activity by around 30%. However, other antimicrobials remain mostly unchanged (, , , 33).
Summary Claims that raw milk is more nutritious than pasteurized milk and a better choice for those with lactose intolerance, asthma, autoimmune and allergic conditions have shown to have little or no truth to them.
Due to its neutral pH and high nutritional and water contents, milk is an ideal feeding ground for bacteria (16).
Milk essentially comes from a sterile environment within the animal.
From the moment the animal is milked, the potential for contamination begins with the udder, skin, feces, milking equipment, handling and storage (, ).
Contaminations are not visible to the naked eye and are often not detectable until growth is significant ().
The majority — but not necessarily all — bacteria are destroyed during pasteurization. The ones that survive, mostly do so in a damaged, non-viable form (, ).
Studies show that raw milk contains significantly higher quantities of harmful and introduced bacteria than pasteurized milk (16, , , ).
Keeping milk refrigerated helps suppress bacterial growth, no matter if it’s raw or pasteurized ().
Bacteria and Symptoms
Harmful bacteria that may be present in milk include Campylobacter, Salmonella, Escherichia coli (E.coli), Coxiella burnetti, Cryptosporidium, Yersinia enterocolitica, Staph aureus and Listeria monocytogenes (3, , 16).
Symptoms of infection are comparable to those of other foodborne illnesses and include vomiting, diarrhea, dehydration, headaches, abdominal pain, nausea and fever ().
These bacteria can also cause serious conditions, such as Guillain-Barre syndrome, hemolytic uremic syndrome, miscarriage, reactive arthritis, chronic inflammatory conditions and, rarely, death (, , ).
Who Is Most at Risk?
Any person is susceptible if the milk they consume contains harmful bacteria.
However, the risk is higher for pregnant women, children, older adults and those with weakened immune systems.
More than half of all disease outbreaks associated with raw milk have involved at least one child under the age of five ().
Severity of Raw Milk Outbreaks
A foodborne outbreak is the incidence of two or more reports of an illness as a result of consuming any common food ().
Between 1993 and 2006, 60% of the 4,413 reports of dairy-related illnesses (121 outbreaks) in the US were from raw dairy, including milk and cheese. Of the milk-only outbreaks, 82% were from raw milk, compared to 18% from pasteurized (, 43).
During the same period, two deaths from raw dairy and one from pasteurized dairy occurred, while three more have been reported since (, , ).
Those infected by consuming raw milk were 13 times more likely to need hospitalization than those consuming pasteurized milk ().
Related outbreaks, hospitalization and death rates are high considering that only 3–4% of the American population drinks raw milk ().
More recent data has shown that raw milk or cheese causes 840 times more illnesses and 45 times more hospitalizations than pasteurized dairy ().
Currently, many countries ban raw milk for human consumption, including Australia, Canada and Scotland. It’s prohibited in 20 American states, while other states restrict its sales. In addition, it cannot be sold across American state lines (47).
However, the number of outbreaks is increasing, especially in states that have legalized its sale (, , ).
Summary Raw milk can contain harmful bacteria that may lead to serious illness, particularly in pregnant women, children, older adults, and immunocompromised people. Infections are more frequent and severe than those caused by pasteurized sources.
Raw and pasteurized milk are comparable in their nutrient contents.
While raw milk is more natural and may contain more antimicrobials, its many health claims aren't evidence-based and don’t outweigh potential risks like severe infections caused by harmful bacteria, such as Salmonella, E. coli and Listeria.