The value (or lack thereof) of dairy products is the second most fiercely debated topic within the paleo community (after carbohydrate intake).  Opinions vary dramatically from consumption of no dairy whatsoever, to only consuming dairy fat (such as ghee, butter and heavy cream), to only consuming raw grass-fed dairy, to only consuming fermented dairy or aged cheeses, to including any dairy on a regular basis.

The reason for this diversity of opinions is that the science is not clear cut.  There are strong arguments to be made both for and against.

Let’s start with the arguments against dairy.  Prof. Loren Cordain dedicates an entire well-cited chapter in his most recent book The Paleo Answer (a fantastic book for describing the nitty gritty scientific details behind the paleo diet) to the many reasons why milk should not be consumed in any form.  To summarize, what I view the strongest parts of this argument:

• Milk is not as nutrient-dense as meat, fruits and vegetables.
• Milk is highly insulinogenic, meaning it causes a large spike in blood insulin levels, disproportional to the amount of sugar and protein in milk.  This may contribute to the development on insulin resistance, at least in the context of a high carbohydrate diet.  Insulin is also pro-inflammatory.
• Milk contains active bovine (cow) hormones which have the potential to alter our hormone levels.  The effects of dietary intake of most of these hormones have not been studied.  However, other hormones have been studied.  For example, the milk hormone Insulin-like Growth Factor-1 (IGF-1) has been linked to risk of breast, colorectal and prostate cancer, with the strong indication that consumption of dairy protein is a large contributor to blood IGF-1 levels ¹.
• Milk contains protease inhibitors which may contribute to the development of a leaky gut (see this post for a more in depth explanation as to why)
• Milk increases mucus production.  This may aggravate conditions such as asthma but also creates excess mucus in the gastrointestinal tract which may irritate the gut lining and inhibit nutrient and mineral absorption.
• Lactose is poorly tolerated by adults.  Approximately 25% of Caucasians (American and European) are lactose intolerant.  97% of Native Americans are lactose intolerant.  This argument does not apply to drinking raw milk since raw milk contains enzymes to help digest lactose.
• Dairy is highly allergenic.  This is where I believe the chief argument against dairy lies and I will discuss this further below.

There are also some very compelling arguments for including dairy products in our diets.  Studies have shown that consumption of dairy, especially full-fat dairy products and fermented dairy products, can protect against Metabolic Syndrome (cheese, full-fat dairy, and fermented dairy), Type II Diabetes (fermented dairy only) and Cardiovasular Disease (cheese, full-fat dairy, and fermented dairy) ^2-6.

Grass-fed dairy, especially the fat from grass-fed dairy, is an excellent source of fat-soluble vitamins and Conjugated Linoleic Acid, an anti-inflammatory and healing fat.  Fermented dairy is an excellent source of probiotics.  There are also some valuable proteins in dairy, such as glutathione (very important for reducing inflammation and protecting against oxidative stress) and whey (which may help prevent cancer).

There is also evidence that dairy proteins are beneficial for children due to their growth-promoting effects.  Traditionally, children would have received some breast milk until approximately 5 years of age.  In our current society, most children are weaned by age 1.  The current scientific view is that, provided cow’s milk is not introduced too early, it is a good substitute for human milk in terms of its growth promotion ⁷.

Yes, the science is not clear, although there seems to be a good case for including dairy fat in our diets.  This is why the standard paleo diet allows for ghee and butter, and in many cases heavy cream and full-fat sour cream.  Many people also include fermented dairy in their diets with great success.

However, one thing that is abundantly clear is that milk allergy is common.  Beyond lactose-intolerance, which can be treated with the aid of digestive enzymes or consumption of raw milk, allergy to milk proteins is very common.  Epidemiological reports of cow’s milk allergy (IgE antibody reactions to cow’s milk proteins) range between 1 and 17.5% in preschoolers, 1 and 13.5% in children ages 5 to 16 years, and 1 to 4% in adults ⁸.  It is not known how prevalent cow’s milk sensitivities are (IgA and IgG antibody reactions to cow’s milk proteins).  It’s important to note that goat’s milk is not as allergenic as cow’s milk.

Cow’s milk proteins are also known gluten cross-reactors, which means that those with gluten intolerance may produce antibodies against gluten that also recognize dairy proteins.  For these people, eating dairy is the same as eating gluten (more information in this post).  Very importantly, for people with allergy, intolerance or gluten cross-reactions to dairy proteins, even the trace dairy proteins in ghee can be a problem.

So, what do I recommend?  Caution.  I believe that dairy is probably okay for many healthy adults, especially full-fat, grass-fed dairy.  In fact, for healthy individuals, the benefits likely outweigh the risks.  However, for those battling autoimmune disease or other conditions where a leaky gut is a potential contributing factor, it makes the most sense to omit dairy from your diet for now.  As is my standard recommendation for all of the gray-area foods, I suggest leaving it out of your diet for at least 1 month, then try reintroducing it and see if you notice any obvious symptoms (this is the best way to determine if you are allergic or sensitive).

I am still trying to gauge my own tolerance for grass-fed butter.  My daughters both seem to do better without cow’s dairy in their diets (except grass-fed butter, which seems okay), but I have reintroduced grass-fed goat mineral whey protein powder into their diets and they seem to do really well with that (especially my oldest).  I also have intentions to try them with some grass-fed goat’s whole milk.  This is another highly individual aspect of a paleo diet and you really don’t know whether or not milk is good for you until you try living without and then try living with.

1. Crowe FL et al “The association between diet and serum concentrations of IGF-I, IGFBP-1, IGFBP-2, and IGFBP-3 in the European Prospective Investigation into Cancer and Nutrition.” Cancer Epidemiol Biomarkers Prev. 2009 May;18(5):1333-40.

2. Louie JC et al “Higher regular fat dairy consumption is associated with lower incidence of metabolic syndrome but not type 2 diabetes.” Nutr Metab Cardiovasc Dis. 2012 Sep 26. pii: S0939-4753(12)00193-7. doi: 10.1016/j.numecd.2012.08.004. [Epub ahead of print]

3. Warensjö E, et al. “Biomarkers of milk fat and the risk of myocardial infarction in men and women: a prospective, matched case-control study.” Am J Clin Nutr. 2010 Jul;92(1):194-202. Epub 2010 May 19.

4. Sonestedt E et al. “Dairy products and its association with incidence of cardiovascular disease: the Malmö diet and cancer cohort.” Eur J Epidemiol. 2011 Aug;26(8):609-18. doi: 10.1007/s10654-011-9589-y. Epub 2011 Jun 10.

5. Sluijs I et al “The amount and type of dairy product intake and incident type 2 diabetes: results from the EPIC-InterAct Study.” Am J Clin Nutr. 2012 Aug;96(2):382-90. Epub 2012 Jul 3.

6. Bonthuis M et al. “Dairy consumption and patterns of mortality of Australian adults” European Journal of Clinical Nutrition (2010) 64, 569–577; doi:10.1038/ejcn.2010.45; published online 7 April 2010

7. Agostoni C and Turck D. “Is cow’s milk harmful to a child’s health?” J Pediatr Gastroenterol Nutr. 2011 Dec;53(6):594-600.

8. http://www.worldallergy.org/publications/WAO_DRACMA_guidelines.pdf

Chris Kresser has a terrific post Dairy: food of the Gods or neolithic agent of disease?

The Paleo Answer by Prof. Loren Cordain is an excellent resource.