What if you could eat to beat diabetes?

You can. New research shows that people who are willing to more than double the fiber in their diets from 16 to 37 grams per day can better control diabetes. It needs to be a high amount of diverse types of fibers, and getting nearly 40 grams may sound like a tall order, but it’s actually not that hard—and it could make a radical difference in your blood sugar level.


Common thinking about why fiber is good for people with type 2 diabetes is that fiber slows down your digestive system. That means less of a sugar spike after eating, important when your body doesn’t make enough insulin to handle a high sugar load. Fiber also makes you feel full on less food, and that can help with weight loss, an important goal for many people with diabetes. This means that the benefits are from the physical properties of fiber themselves rather than from improving glycemic control.

But when researchers followed two groups of people with diabetes eating different amounts of fiber, they found that people who ate nearly 40 grams of diverse fibers a day actually regained their own glycemic control back to a higher level than the group that ate only 16 grams—a win-win-win for the 37-gram eaters. The high-fiber- intake group showed a steady increase of insulin secretion and insulin sensitivity, borne out with rigorous medical tests such as the oral glucose tolerance test (OGTT) at the end of each month on the new diet for three consecutive months. This demonstrated that the high-fiber diet actually led to better glycemic control and does not just reduce the sugar load of your diet and make you feel full. Something more fundamental happened.

How that works: By studying the gut bacteria, or gut biome, of the participants, the researchers found that intake of diverse fibers selectively increased a group of bacteria that digest fiber and produce a type of substance called short-chain fatty acids. Higher levels of these acids, acetic and butyric acids, were linked to an increased production of the hormone GLP-1, known to increase insulin secretion.

Interestingly, production of these acids also reduced the pH of the gut, which makes it a less favorable environment for other not-so-good-for-you bacteria, such as producers of indole and hydrogen sulfide, two smelly and toxic compounds that can inhibit GLP-1 production. Endotoxin producers, which can induce inflammation and damage insulin receptors, were also reduced, leading to high insulin sensitivity of all body cells of the patients. Think of it this way: Picture cultivating a tall tree so that it forms a tight canopy that creates a special environment within the forest. This group of fiber-utilizing gut bacteria are the tall trees of our healthy “gut forest.” Eating enough fibers to grow your tall tree gut bacteria may be critical to your health.

In a nutshell, more diverse fibers means more insulin and higher insulin sensitivity, explains lead study author Liping Zhao, PhD, of Rutgers University. Dr. Zhao believes that feeding those short-chain fatty acid-producing bacteria more fibers will not only help people manage type 2 diabetes, it also may help reduce the risk of developing type 2 diabetes, important for people diagnosed with metabolic syndrome or prediabetes.


Here’s a bit of hominid history you may or may not want to share at your next dinner party. According to Dr. Zhao, studies of fossilized feces from our ancient ancestors shows that they may have eaten 200 to 400 grams of fiber every day! The point being, our modern diets are truly puny in fiber compared with what our bodies might have evolved for. Today, the average American eats only about 16 grams of fiber per day, not nearly enough to get fiber’s diabetes-fighting (or many other) benefits.

To get 37 grams of fiber into your diet each day without overeating, you’re going to want to choose foods that provide the most grams per serving. When you read nutrition labels, focus on the number of grams rather than the percentage of the recommended daily amount, because that’s based on the lower guideline of 25 grams per day. Here are some of the foods highest in various fibers…

  • Beans (15 grams in 1 cup of cooked black beans)
  • Split peas (16.3 g in 1 cup cooked)
  • Lentils (15.6 in 1 cup cooked)
  • Fruits, especially those with edible skins (8 g in 1 cup raspberries, 5.5 g in a medium pear)
  • Vegetables (10.3 g in 1 medium artichoke, steamed, 8.8 g in 1 cup cooked green peas and 5.1g in 1 cup cooked broccoli)
  • Whole grains (5 g in ½ cup rolled oats uncooked, and 6 g in 1 cup cooked pearl barley)
  • Nuts and seeds (5.2 g in 1.5 ounces almonds, 5.6 g in 2 tablespoons of flaxseed)

Note: If you’re wondering if fiber supplements are an easy way out, they’re not. You not only need a steady amount of fiber across the day, but you also need the very diverse mix of fibers available through food.

Important: Work with your certified diabetes educator or endocrinologist on the best way to increase your fiber intake as part of your blood sugar management.


The future of fiber and the gut biome may be personalized nutrition. Since everyone’s biome is different, tests will measure which bacteria in your gut respond best to which high-fiber foods and in what quantity. With this information, you will be able get your gut biome into top shape. These tests are already being studied, says Dr. Zhao.

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