I heard it claimed that nuts were inflammatory. It is not easy to google up any evidence to back that idea up; conversely, it is easy to google up evidence that nuts are either anti-inflammatory or have no substantial effect on inflammation.

The article shown at the very top of this post is a meta-analysis looking at a number of studies on nuts, finding little overall effect on inflammation. There is, however, an intriguing drop in leptin from eating nuts, which suggests that nuts may be less satiating than one would otherwise expect, making it easy to eat a lot of them. The current version of the Wikipedia article “Leptin” says “Leptin (from Greek λεπτός leptos, "thin") is a hormone predominantly made by adipose cells and enterocytes in the small intestine that helps to regulate energy balance by inhibiting hunger …”

The second article shown above suggests that nuts are anti-inflammatory. Part of the difference may be the emphasis in this second article on nuts crowding out less healthy foods. Often, the question “Is food X healthy?” should be the questions “Compared to what?” Many, many things are quite unhealthy compared to nuts, making nuts healthy compared to them.

A comparison of nuts to eating nothing might give a different answer about whether nuts are inflammatory. That is, compared to a water fast—eating nothing, but still continuing to drink water—nuts could cause some inflammation. This would not at all contradict the idea that eating nuts instead of, say, eating potato chips, was anti-inflammatory. Not that the comparison to something like potato chips is a very relevant comparison for daily eating habits. (See “Our Delusions about 'Healthy' Snacks—Nuts to That!”)

In any case, if nuts were strongly inflammatory, this would probably be quite visible in experiments that have been done. So the available evidence does provide some confidence that they are not strongly inflammatory for the average person who does not have a specific nut allergy. And it isn’t just nuts in general: no particular type of nuts seems to show up as strongly inflammatory in prominent studies.

What I was looking for as evidence of an inflammatory effect was the short-term response of inflammation immediately after eating nuts along the lines of evidence about the insulin-response to food and the glycemic response to food, but with a short-run inflammatory outcome measure. (On this type of measure for insulin response and glycemic response, see “Forget Calorie Counting; It's the Insulin Index, Stupid” and Using the Glycemic Index as a Supplement to the Insulin Index.) I did not immediately find evidence like that on short-run inflammatory responses soon after eating nuts or other foods.

I’d be glad to hear more opinions on the question of whether nuts are inflammatory and on other questions about how healthy nuts are in general and whether some nuts are healthier than others.

For annotated links to other posts on diet and health, see:

• Miles Kimball on Diet and Health: A Reader's Guide