The press release had a curious title: “Omega-3 fatty acids protect against Parkinson’s.” The certainty suggested an experiment, but Parkinson’s is too rare to study prevention experimentally. The press release turned out to be about a rat study that used a drug called MDPT to cause brain damage that resembles Parkinson’s. Rats given a high-omega-3 diet suffered much less damage — apparently none — from the drug.
Rats given the high omega-3 diet had much less omega-6 in their brains than control rats — one more reason, in addition to the Israeli Paradox, to think that omega-6 may be just as bad as omega-3 is good. Omega-3 may act by displacing omega-6 (they are almost identical physically).
The results could have been taken to suggest both (a) eat more omega-3-rich foods, such as fish and (b) eat less omega-6-rich foods, such as most nuts and vegetable oils, but only the first recommendation reached the public.
Suggesting that people avoid nuts seems counterproductive. Nuts are among the only foods for which consumption is consistently and dramatically linked to lower heart disease (and all-cause) mortality in epidemiologic studies, and lab and animal studies are also suggestive of protection from vascular diseases.
Thanks, David, that’s a good point. I was aware of experiments suggesting that walnuts — which are high in omega-3, one of the few nuts that is — have heart-protective effects. But I’d forgotten about the studies you mention. I found this in a 1999 paper: “Perhaps one of the most unexpected and novel findings in nutritional epidemiology in the past 5 y has been that nut consumption seems to protect against ischemic heart disease (IHD).” It’s also true that while vegetable oils are high in omega-6, nuts contain far more than fat. Vegetable oils are close to the sum of the fats they contain; nuts aren’t.
https://ifitandhealthy.com/healthy-diets-the-mediterranean-diet/
When it comes to a fatty acid composition of oils, the best omega-6 to omega-3 ratio is found in flaxseed, canola, walnut, olive, and avocado oils.
Omega-6:Omega-3 Ratio in oils:
Flaxseed – 0:24
Canola – 2:00
Walnut – 5:08
Olive – 13:1
Avocado – 13:0
In nuts, the best omega-6 to omega-3 ratio is in walnuts, macadamia, pecans, cashews, and pine nuts.
Omega-6:Omega-3 Ratio in nuts:
Walnuts – 4:2
Macadamia – 6:3
Pecans – 20:9
Pine – 31:6
Cashews – 47:6
If you have a choice, it is a good idea to use nuts and oils with a good omega-6 to omega-3 ratio.