Beans Fight Diabetes:

Beans Seen to Discourage Weight Gain and Diabetes

Part 2

Click here for part 1

by Craig Weatherby
Courtesy of Vital Choice Seafood

Beans offer pound-shedding protein in a tasty package

Beans and other legumes are ample, weight-controlling sources of protein.

While beans can’t replace the unique benefits of omega-3-rich fish or match its protein content, they and other legumes can replace almost all need for animal protein when combined with a little bit of whole grain to boost the level of nutritionally complete protein in both.

Beans and lentils also come in a wide variety of flavors, shapes, sizes and textures, lending themselves to a broad range of uses, and making it easy to choose one compatible with most any meal.

Of the 29 food and feed ingredients studied by a team at the University of Illinois at Urbana-Champaign (see table, below), the seven legumes tested offered substantially higher percentages of dietary fiber and resistant starch.

Black beans contain the highest amount of total dietary fiber (43 percent), and 63 percent of their total starch content is resistant starch that makes it to the colon to ferment, with beneficial results.

But in terms of making the least impact on blood sugar, an uncommon—but obtainable—legume from the Indian subcontinent may be the best bean of all.

This lentil, called chana gram dal, comes from a distinct variety of the same plant that gives us plump yellow chickpeas (Cicer arietinum). However, the chana dal variety of chickpea is much smaller and darker, and also higher in fiber and phytoceuticals.

Indian grocers call these two types of chickpea desi (chana dal) and kabuli (standard yellow chickpeas).

While standard chickpeas rank very low on the glycemic index, chana dal ranks even lower, making it a superstar among the many blood-sugar-stabilizing stars in the legume family.

Grains and resistant starch: Making a good thing better

Cereal grains, especially barley and corn, are second only to beans in their percentages of resistant starch.

Whole grains contain much more resistant starch than the heavily processed flours made from them.

But even whole grains are second best to legumes (beans, lentils). In addition to a lower percentage of resistant starch, grains have less fiber than beans, making them less beneficial with regard to the overlapping benefits of both kinds of indigestible carbohydrates.

And you can actually increase the percentage of resistant starch in fresh-baked bread or in cooked pasta and potatoes just by cooling them quickly: a process called “retrogradation”.

When you heat a starchy food like bread or pasta the digestible starchy adopts a gel-like form, and when you cool it quickly, it morphs into digestion-resistant forms.

This is what happens to bread when it cools after cooking: a process you can promote and accelerate by putting fresh-cooked bread in the refrigerator.

And ever wondered why, despite the Atkins Diet’s critical stance toward spaghetti, the traditional, pasta-centered rural Italian diet--one of the “Mediterranean” approaches to eating considered preventive-health paragons--doesn’t produce many overweight people?

To be sure, the small portions of pasta, fishy diets, and manual labors of rural Italians explained some of the health benefits found among them and their Cretan counterparts by the famed Seven Countries Study, which began in the 1960’s and led to lionization of both populations’ classic Mediterranean diets.

But the tradition of rinsing cooked pasta in cold water, while done to reduce stickiness, had the side benefit of literally making this unfairly maligned white-flour food considerably less glycemic and caloric.

Likewise, you can raise the resistant starch content of potatoes considerably by chilling them immediately after cooking: a trick that makes potato salad healthier than a hot potato, especially if you leave in the fiber- and antioxidant-rich skins.

Corn comes in from nutritional cold

Conventional wisdom holds that corn is full of rapidly absorbed, blood-sugar-spiking starches and sugars and low in nutrients.

But let’s not be so hasty to abandon as unhealthful the staple food of most indigenous Americans, which served them very well over millenia.

In addition to the fact that whole corn is quite high in antioxidants, research released this year by scientists at the the Louisiana State University Agricultural Center show that fermentation of natural resistant starch from one corn has considerable positive impact on cellular metabolism and accumulation of body fat.

Drs. Michael Keenan, Jun Zhou and Roy Martin of the LSU Agricultural Center also conducted a series of studies to pinpoint the sources of the overlapping anti-obesity effects of dietary fiber and resistant starch.

As they reported at the 2006 Annual Meeting of the North American Association for the Study of Obesity, “By comparing diets matched for different variables, we were able to show that the fermentation was the mechanism with the greatest impact of the three mechanisms tested.” (As we’ve seen, both fiber and resistant starches offer bacteria fertile fare to ferment.)

Earlier animal research by the same team showed that the dietary consumption of a corn-derived resistant starch raised levels of key satiety hormones (PYY, proglucagon, GLP-1) and significantly and reduced abdominal fat in the experimental rodents.

Dr. Keenan said this at the time: “We believe the fermentation of resistant starch may be an effective natural approach to the treatment of obesity. The advantage of the resistant starch is that it can be added to foods more readily than non-fermentable fiber.”

Resistant starch and fiber content of beans and grains

The table below, based on research by Dr. George C. Fahey and his team at the University of Illinois at Urbana-Champaign, shows how much of the starch in each food is resistant. (The two other forms of starch (rapidly digesting and slowly digesting) are broken down in earlier stages of digestion, and are not shown here.)

Note the differences between the whole and refined versions of grains: for example, brown rice vs. white rice flour, whole wheat vs. white (refined) wheat flour or corn kernels vs. corn meal and hominy grits. It is interesting to see that there is little difference between brown and white rice, with both being pretty rich in resistant starch.

The percent of resistant starch reaching the colon is important because that is the portion available to be fermented, with beneficial anti-cancer and appetite-suppressing effects.

Food

Percent of starch

that is resistant

Percent of resistant starch that reaches the colon

Black beans

26.9

62.7

Red kidney beans

24.6

57.7

Lentils

25.4

47.7

Navy beans

25.9

52.5

Black-eyed peas

17.7

32.8

Split peas

24.5

37.9

Northern beans

28

56.1

Barley (whole)

18.2

33

Corn (whole kernel)

25.2

32.3

White rice

14.1

14.8

Brewer's rice

3.5

4.1

Brown rice

14.8

16.8

Whole wheat

13.6

26.8

Mlllet (whole)

12.6

14.6

Oats (rolled)

8.5

15.2

Corn flour

11

13

White flour (wheat)

1.7

2.5

White rice flour

1.6

1.8

Potato starch*

66.9

2.1

Soy flour

0.6

10.9

Barley flour

1.2

1.7

Macaroni

6

8

Spaghetti

3.3

4.5

Corn meal

5

5.7

Rice bran

3.4

11.9

Corn grits (hominy)

8

12.3

 

 

*Note: We are not sure how the researchers define "potato starch", which their figures suggest has a very high proportion of resistant starch (66.9 percent). Given the generally medium-to-high glycemic indices and glycemic loads of baked and boiled potatoes, we cannot assume that this figure means that cooked, un-chilled potatoes are as high in resistant starch. (To see the GIs and GLs of many foods, go to mendosa.com/gilists.htm.)

So when you’re planning meals, don’t overlook beans--alone or with a little whole grain or “retrograded” pasta or potato--as your carbohydrate component. Your waistline--and healthier future self--will thank you.

Editor's note: We consider organic whole foods from both plant and animal kingdoms to be a major key to superior health. We also think it's terribly important to eat fish at least twice a week to get the essential fatty acids. Here at our house, we only eat wild Alaskan salmon and other wild seafoods from our friends at Vital Choice. Click here to visit Vital Choice Seafood.

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