Potato intake and incidence of hypertensionby Emma Simpson on May 19, 2016
Lots of people have been asking me about the study that potatoes cause hypertension.
The study looked at the Nurses health and the Health Professions database. They found that boiled potatoes, mashed potatoes, and french fries BUT NOT CHIPS were a
ssociated with increase blood pressure.
The database is a reliable database that has been followed for many years. It has its flaws but is nonetheless a good database and the authors are all respected and funded by NIH.
Now, in order to decide whether there was a difference between eating potatoes and not eating potatoes there has to be a control. In other words, potatoes are more likely to cause hypertension compared to what?
In this situation they were comparing people who ate potatoes(in the various forms) vs non starchy vegetables. Well, this seems obvious to me. As I write about in my book, non starchy vegetables are high in glutamic acid which is converted to glutathione which will aid vasodilation which will actually decrease BP. More veggies will always improve health.
I think the authors struggle in this article coming up with a mechanism of action. They claim that the high glycemic index results in the high blood pressure but there is no pathophysiologic mechanism for this unless you start looking at indirect effects that should have been controlled for.
They also have a hard time explaining why potato chips had no effect. They say that it may me a confounder like BMI, though they tested BMI and controlled for it.I would also add that while they achieved significant p value, it was close and standard deviation was large.
I think starches are great. Potatoes have been showing to be the most satiating food you can eat, and sweet potatoes (my preferred starch) are loaded with phytonutrients that have demonstrated protective effects against cancer. Also resistant starches found in potatoes may be very good for our micro biome.
I do, however, an issue with starches eaten with meats. It may be that animal protein, animal fat and starches combined yield a negative effect. I write about this extensively in my book. The problem with the population they are studying is that they eat a standard American diet. It can be assumed therefore that they have intramyocellular fat and insulin resistance. If you are insulin resistant and you add starches you will not be able to process the carbs correctly.
On a predominately plant based diet, you can process starch perfectly. Starches therefore become part of a healthy diet. This is why you see societies that eat a predominately starch based diet having such great health.