At Parkinson’s on the Move, we stay away from endorsing any particular diet plan mainly because there are so many factors that go into how we individually react to a particular diet. Trends come and go. Diet fads come and go. In the end, we are left to our own devices to sift through ideas to formulate our own. We must choose who to believe, what to believe, and go from there. Ideally, we can base these decisions on sound research. But, as is the case with the majority of lifestyle interventions, these studies are flawed. At the end of the day, you aren’t studying dietary or lifestyle modifications in a closed environment. You have compounding factors.
What is clear to us, however, is that diet does matter. Diet matters not only for people with Parkinson’s, but for society as a whole. In medical school, physicians in training are not really taught about nutrition in a practical sense. Sure, we learn about epidemics of obesity, of diabetes. Yes, cholesterol metabolism is discussed in detail. Yes, the genetics of G6PD deficiency are discussed and the fact that fava beans can trigger hemolytic anemia in that population is learned. But what a “good” diet truly entails, well, that’s up to the individual to decide. So, if your doctor does not follow a healthy diet, are we surprised that it’s not a focus of your care?
Perhaps part of the reason why diet is so often brushed aside is because it is so hard to make concrete statements. Genetics, environmental conditions, the exact foods and combinations, cooking and processing methods… all of these and other factors can affect how people react and respond to the foods they consume.
A few days ago, a new study was published looking at a group (>1000) of Parkinson’s patients self-reporting diet and supplement usage alongside PD symptom severity.
Not surprisingly, they found the following foods to be associated with lower PD severity:
- Fresh vegetables
- Fresh fruit
- Nuts
- Fish
- Olive oil
- Wine (red vs. white is not specified)
- Coconut oil
When it comes to foods associated with worse symptoms… well, the only one that I would really draw a conclusion about is diet sodas, an item we have discussed before here. Although canned fruits and canned vegetables also appear to be associated with worse PD severity, simply eating from food a can appears to have no association. While the authors claim other foods are statistically linked to worse progression (ice cream, cheese, yogurt… and, in general, dairy), the data do not really support those claims. I say that based on the statistical methods (no multiple hypothesis testing), as well as the actual P-values. What the data do show is that for certain foods, income appears to have a large effect. This is particularly true of beef and yogurt. That makes me worry about the quality of the products a lot of us are consuming, which is a concern many have of the U.S. food industry as a whole, but actually indicates to me that the foods in their healthiest form most likely are not detrimental to individuals with PD.
There is also a whole host of foods which do not seem to affect PD progression either way, which I’m inclined to believe. The statistics were run to minimize the likelihood of missing something which could possibly be associated, which in turn increases the error that something appears to be associated (this is the multiple hypothesis issue I brought up before).
Like many other studies looking at diet, there are clear flaws and an over-interpretation of data. But, the data itself is useful (see Table 2 of the paper below), and I do think it provides some interesting insights that we can all use. In particular, it should motivate us to focus on a diet that places a high emphasis on fruits and vegetables… and to stop using artificial sweeteners. It also should show us that yes, diet matters… and that we need to pay attention to it.
Here is the link to the original article discussed above: https://www.hindawi.com/journals/omcl/2017/6405278/
Please note that these are my personal opinions of the data. We are happy to discuss thoughts, ideas, questions in the comments below!