Resistant Starch in Foods
Once you’ve become interested in the health benefits of resistant starch (RS), you are going to want to know where to get it. Just like “If You Give a Mouse a Cookie” by Laura Numeroff. (That mouse now wants a glass of milk, if you don’t remember the popular children’s story.) I do not know of anybody who learns of resistant starch’s benefits and does not ask where it is available, and I’ve been talking about resistant starch for more than a decade!
An excellent article by Mary Murphy, Judith Douglass and Anne Birkett was published in the Journal of the American Dietetic Association in 2008. Table 1 summarizes the foods with the highest quantities of resistant starch in the American diet, from all of the foods identified in the Murphy article. In short, foods in general provide relatively low levels, but if you are eating these foods consistently, you can get reasonable quantities. Food processing most often breaks down the resistant starch and makes starch more digestible. For instance, 1/4 cup of uncooked oats (i.e., from muesli) contains 4.4 grams of RS but 1 cup of cooked oats contains only 0.5 grams of RS.
To put this in perspective, researchers have suggested that you would need to consume 20 grams of resistant starch each day to get the full benefits for digestive health. Most researchers have used 15-30 grams of resistant starch per day for their studies. That’s a lot of beans, bananas and raw oats each and every day!
The Murphy article concluded that Americans consume between 3 to 8 grams of resistant starch per person. Breads, cooked cereals/pasta, and vegetables (other than legumes) contributed 21%, 19% and 19% of total resistant starch intake, respectively. Bananas and plantains provided 14% of resistant starch intake and legumes accounted for approximately 9% of daily intake. Breads and cooked cereals/pasta deliver low quantities of RS3 – i.e., whole wheat bread contains 1.0 gram of RS per 100 gram of bread. Because Americans consume so much of these grain-based foods, they constitute much higher percentages than legumes, which are excellent sources of resistant starch, but are consumed much less frequently.
A similar article from authors at Shangdong University, Jinan, China was published on the resistant starch intake in the Chinese diet in 2010. It is publicly available, but focuses on foods typical in a Chinese diet. It’s informative, if you like to see the details. For instance, they report that a raw, green banana has 18.7% total starch and 38.3% of that is resistant starch. Completing the math, that is about 7 grams of resistant starch/100 grams of banana starch. One source (EUFIC) identifies that bananas have about 25% starch, which would mean that bananas contain 1.75 grams of resistant starch/100 grams of banana. In contrast, a raw, ripe banana had 16.7% total starch but only 4.85% of that was resistant starch (or 0.2 grams of resistant starch per 100 grams of banana).
I always believed that if you consumed lower quantities of resistant starch over your lifetime, it would help you to stay healthy and metabolically well. If, however, you are experiencing health issues later in life and are trying to address those issues, you would need higher quantities to try to reverse the condition. That’s what the data suggests.
As a result, food sources of resistant starch may be sufficient if you are still healthy, but may be insufficient if you are trying to address a health issue. Raw foods are better than cooked or processed foods. Natural foodies will argue with me, as this conclusion may not be politically correct in their community, but I stand by the data, until otherwise proven.
If you want faster results, more reliably, supplement with RS2 resistant starch from high amylose corn, raw potatoes or perhaps raw, green bananas (if it can be quantified as the levels can vary dramatically). Eating foods rich in resistant starch helps too.