Parkinson’s disease, the second most common neurodegenerative disorder after Alzheimer’s, is characterized by a slowness of movement, rigidity, tremor, and stooping posture, all of which worsen over time. Non-movement symptoms such as cognitive impairment and sleep, smell, and mood disturbances occur as the disease spreads to other areas of the brain. The cause of Parkinson’s is perhaps “one of the important questions posed by the neurobiology [science] of aging.” For example, why is the consumption of dairy products associated with increased risk of Parkinson’s? Perhaps because they contribute to our exposure to pesticides and other neurotoxins like dieldrin, which continues to be found in the autopsied brains of Parkinson’s victims. Even though dieldrin was banned decades ago, it lingers in the environment and we “continue to be exposed to the pesticide through contaminated dairy and meats…”

The cause of Parkinson’s “is unlikely to be due to milk compounds such as calcium, vitamin D, total fat, or total protein as these compounds are not associated with [the disease] when derived from other sources.” However, it could be lactose, the milk sugar, perhaps accounting for the increased associated risk of death and bone fractures, as well as Parkinson’s. Earlier onset of Huntington’s disease has also been identified. There is, however, a third possibility.

As I discuss in my video Parkinson’s Disease and the Uric Acid Sweet Spot, milk lowers uric acid levels, and uric acid may be protective against Huntington’s and also slow the decline caused by Parkinson’s. More importantly, it may lower the risk of getting Parkinson’s in the first place. Why? Perhaps because uric acid is an important antioxidant in the brain, something we’ve known for more than 30 years. We can demonstrate uric acid’s importance directly on human nerve cells in a petri dish. When the pesticide rotenone is added, oxidative stress goes up. Add the pro-oxidant homocysteine, and it goes up even more. But, when uric acid is added, it completely suppresses the oxidative stress caused by the pesticide.

Drinking milk, however, has a uric acid-lowering effect. In the paper making this assertion, a study they cited was “A cute effect of milk on serum urate concentrations,” but that was just a cute typo—they meant Acute effect. Indeed, drink cow’s milk, and, within hours, uric acid levels drop 10 percent. Drink soymilk, and, within hours, they go up 10 percent. Now, for gout, a painful arthritic disease caused by too much uric acid, the uric acid-lowering effect of dairy is a good thing—but uric acid is “a double-edged sword.”

If our uric acid levels are too high, we can get gout, but, if they’re too low, it may increase our risk of neurodegenerative diseases, such as Alzheimer’s, Huntington’s, Parkinson’s, and multiple sclerosis.

Incidence rates of gouty arthritis over five years indicate that if our uric acid is over 10.0 mg/dl, we have a 30 percent chance of suffering an attack of gout within the next 5 years. However, at levels under 7.0 mg/dl, our risk is less than 1 percent, so it might make sense to have levels as high as possible without going over 7.0 to protect the brain without risking our joints. But having excessive uric acid in the blood puts more than just our joints in jeopardy. Yes, having levels that are too low may increase our risk of MS, Parkinson’s, Alzheimer’s, and even cancer, but having levels that are too high may increase our risk of gout, kidney disease, and heart disease.

In fact, having a uric acid level over 7.0 mg/dl isn’t only associated with an increased risk of gout, but also an increased risk of dying from all causes. However, having a low uric acid level may also shorten our lifespan by increasing mortality. High uric acid levels are associated with increased risk of death from heart disease, but low uric acid levels are associated with increased risk of fatal stroke. So, keeping uric acid at optimum levels, the sweet spot between 5.0 and 7.0 mg/dl, may protect the brain in more ways than one.

If we measure the uric acid levels in patients with Parkinson’s, they come in around 4.6 mg/dl, which may help explain why dairy consumption may increase risk for Parkinson’s since milk pushes down uric acid levels. Dairy intake may also explain the differences in uric acid levels among meat-eaters, vegetarians, and vegans. In the graph in my video, you can see that vegan men have significantly higher uric acid levels at 5.7 mg/dl than vegetarians, presumably because vegans don’t drink milk, and those who both eat meat and consume milk fall between the vegans and vegetarians.

For more on Parkinson’s see:

Uric acid as an antioxidant? I’ve touched on that before in Miocene Meteorites and Uric Acid.

If uric acid levels are too high consider cutting down on Flesh and Fructose and eating cherries. (See Gout Treatment with a Cherry on Top and Treating Gout with Cherry Juice for more information.) Also, check out Preventing Gout Attacks with Diet.

In health,

Michael Greger, M.D.