Dairy is anything derived from the milk of a mammal. Cheese, cream, butter, yogurt, ice cream, sour cream, cottage cheese, caramel sauce, hollandaise sauce, chowder. The highest consumers are in the US and Europe.  Most dairy comes from cows, but it doesn’t have to- milk can come from goats, buffalo, camels…It is usually pasteurized, fortified, and homogenized, but sometimes it is fresh and raw. 

While human breast milk is technically dairy, and infants and children are technically dairy consumers, for the purposes of this blog ‘dairy’ will refer to the adult consumption of breast milk from another mammal.

Dairy consumption increases the risk of developing PD

Five studies have asked the question, “Do any foods consumed in adulthood increase an individual’s risk of going on to develop PD?”  Four of the five studies identified the same food- dairy.^1-4 The latest study from Japan did not find a link.⁵

Some of the recent studies looked at specific types of dairy and concluded yogurt was less of a risk than cheese, and cheese less than milk and cream. Is there something harmful in milk and cream? Is there something protective in yogurt that offsets the harm? Or maybe there is nothing harmful in yogurt.

A few things to consider:

Are you lactose intolerant?

Lactase is the enzyme in your gut that breaks down the milk protein lactose. Approximately 50% of elderly are lactase deficient, meaning your body has decided it is time to stop digesting diary. The symptoms of lactose intolerance can be varied- constipation, bloating, gas, bad breath, and/ or loose stools are common. Some people, having dealt with symptoms their whole life don’t even realize how abnormal their bowel function is.

In one study, 9/10 lactose deficient individuals had evidence of small intestinal bacterial overgrowth.⁹ In PD, those with bacterial overgrowth tend to have a more severe disease.¹⁰ A large study in Taiwan just revealed individuals with irritable bowel syndrome (IBS) have an almost 50% increased risk of developing PD!¹¹

Dairy lowers your uric acid

Individuals with gout accumulate uric acid, leading to joint inflammation. Interestingly, individuals who get gout tend not to get PD. It seems that uric acid offers some protection against brain free radicals.⁶ In fact, researchers at Harvard just completed a study of a supplement capable of raising uric acid, inosine. The goal is to determine whether we can raise uric acid levels enough to be protective against PD.

In the meantime, you should know that diary lowers your uric acid levels level.⁷ We aren’t really sure how or why, but those individuals consuming the highest amount of dairy have the lowest uric acid levels.  It seems like avoiding dairy may be a relatively easy and inexpensive way to raise your uric acid levels.

Yogurt and kefir as a source of probiotics

Probiotics are the good bacteria that live in our intestines and play a tremendous role in regulating our immune function. Yogurt and kefir (pronounced ‘kee-fer’) are fermented dairy products and can be an excellent source of probiotics.  In fact, a dairy-based probiotic supplement was recently shown to do a great job improving the bowel health of individuals with PD.⁸ And as I already mentioned, two large, well-designed studies (Honolulu Aging Study and the EPIC-Greece cohort) did show a link between milk and PD, although consuming yogurt did NOT increase the risk of PD.

While they are less commonly studied, non-dairy fermented foods like sauerkraut, kimchi, pickled herring, and kombucha are also sources of probiotics. Don’t be afraid to expand your dietary horizons! In general, the more vegetables, fruits, and fiber you consume, the more probiotics you will naturally harbor.  Probiotics are also available as a dietary supplement, although the quality of many brands is questionable. 

Should you give up dairy if you have PD?

Washing your hands will help prevent a cold, but no amount of hand washing effort will change the course of the cold once you have it.  Perhaps something in, or related to, some dairy you had 20 years ago set in motion a cascade of inflammation and neurological degeneration. Maybe dairy consumption, at this point, is irrelevant and not a significant concern. Also will your diet be deficient in calcium or protein if you do alter the amount of dairy in your diet? Until the research is done, patients and providers need to consider the potential risks and benefits and do what makes the most sense.

(The internet-based survey, ‘CAM Care in PD,’ is currently asking the question, “Does what you eat effect disease severity and progression?” www.CAMCarePD.Bastyr.edu)

You can determine whether you are lactose intolerant, especially if you have any of the symptoms of lactose intolerance described above! Talk to your doctor or healthcare provider about eliminating dairy from your diet for 60 days and then reintroducing dairy with a milkshake or bowl of ice cream. You’ll know pretty quickly how well your digestive system handles the lactose!  If you are lactose intolerant, yes - you should absolutely give up dairy.

If you occasionally enjoy a bit of yogurt, and you’re confident you are eating a brand that has added probiotics, preferably organic, and while doing so, you have at least one, well-formed bowel movement daily, I don’t see a reason to stop.

1.         Chen H, O'Reilly E, McCullough ML, et al. Consumption of dairy products and risk of Parkinson's disease. Am J Epidemiol 2007;165(9):998-1006.

2.         Chen H, Zhang SM, Hernan MA, Willett WC, Ascherio A. Diet and Parkinson's disease: a potential role of dairy products in men. Ann Neurol 2002;52(6):793-801.

3.         Kyrozis A, Ghika A, Stathopoulos P, Vassilopoulos D, Trichopoulos D, Trichopoulou A. Dietary and lifestyle variables in relation to incidence of Parkinson's disease in Greece. Eur J Epidemiol 2013.

4.         Park M, Ross GW, Petrovitch H, et al. Consumption of milk and calcium in midlife and the future risk of Parkinson disease. Neurology 2005;64(6):1047-1051.

5.         Miyake Y, Tanaka K, Fukushima W, et al. Lack of association of dairy food, calcium, and vitamin D intake with the risk of Parkinson's disease: a case-control study in Japan. Parkinsonism Relat Disord 2011;17(2):112-116.

6.         McCarty MF, Barroso-Aranda J, Contreras F. High-dose folate and dietary purines promote scavenging of peroxynitrite-derived radicals--clinical potential in inflammatory disorders. Med Hypotheses 2009;73(5):824-834.

7.         Zgaga L, Theodoratou E, Kyle J, et al. The association of dietary intake of purine-rich vegetables, sugar-sweetened beverages and dairy with plasma urate, in a cross-sectional study. PLoS One 2012;7(6):e38123.

8.         Cassani E, Privitera G, Pezzoli G, et al. Use of probiotics for the treatment of constipation in Parkinson's disease patients. Minerva Gastroenterol Dietol 2011;57(2):117-121.

9.         Almeida JA, Kim R, Stoita A, McIver CJ, Kurtovic J, Riordan SM. Lactose malabsorption in the elderly: role of small intestinal bacterial overgrowth. Scand J Gastroenterol 2008;43(2):146-154.

10.       Gabrielli M, Bonazzi P, Scarpellini E, et al. Prevalence of small intestinal bacterial overgrowth in Parkinson's disease. Mov Disord 2011;26(5):889-892.

11.       Lai SW, Liao KF, Lin CL, Sung FC. Irritable bowel syndrome correlates with increased risk of Parkinson's disease in Taiwan. Eur J Epidemiol 2014.

Laurie K. Mischley, ND, MPH
NWPF Blogger