I posted this in the potato thread, but figured since so many of you are tired of taters, I'd post here, too.

My latest rabbit-hole is resistant starches. Apparently these are very, very important but rarely talked about because they are so easy to get on the SAD. They are mostly found in grains, seeds, and legumes, but also in potatoes and rice. HOWEVER, the potatoes and rice must be cooked and cooled for the biggest effect.

This study shows resistant starches with meals increase fat oxidation that is biologically relevant and could be important for preventing fat accumulation in the long term by effecting total fat balance:
Resistant starch consumption promotes lipid oxidation

Resistant Starches also are converted to butyrates in the large intestine which are a short chain fatty acid. These short chain fatty acids feed the colon flora and protect against whole body and colon inflammation.
Read more: Whole Health Source: Butyric Acid: an Ancient Controller of Metabolism, Inflammation and Stress Resistance

Butyrate has caused me to re-think my position on fiber-- which was formerly that it's irrelevant at best. I felt that fiber came along with nutrient-dense whole plant foods, but was not beneficial per se. I believed that the associations between fiber intake and a lower risk of a number of diseases were probably due to the fact that wealthier, more educated, healthier people tend to buy more whole grains, fruit and vegetables. In other words, I believed that fiber intake was associated with better health, but did not contribute to it. I now feel, based on further reading about fiber and short-chain fatty acids like butyrate, that the associations represent a true cause-and-effect relationship.

I also didn't fully appreciate the caloric contribution of fiber to the human diet. In industrialized countries, fiber may contribute 5 to 10 percent of total calorie intake, due to its conversion to short-chain fatty acids like butyrate in the large intestine (free full text). This figure is probably at least twice as high in cultures consuming high-fiber diets. It's interesting to think that "high-carbohydrate" cultures may be getting easily 15 percent of their calories from short-chain fats. Since that isn't recorded in dietary surveys, they may appear more dependent on carbohydrate than they actually are. The Kitavans may be getting more than 30 percent of their total calories from fat, despite the fact that their food is only 21 percent fat when it passes their lips. Their calorie intake may be underestimated as well."

So, please let your takeaway from this be: Think about adding a source of resistant starch to you diet...cooked and cooled potatoes and rice are specifically mentioned anywhere you see the term 'resistant starch'.