One type of fiber found in oats may induce more weight loss, study finds

• Consuming a diet with adequate fiber is associated with maintaining a healthy weight.
• An animal study recently investigated which form of fiber might be most effective.
• Beta-glucan, a fiber found in cereals and oats, came out on top.

A new study using a mouse model of obesity concludes that a type of fiber called beta-glucan induced more weight loss than other forms of fiber.

If the results are confirmed in human studies, the authors suggest that beta-glucan may be a “promising dietary strategy for metabolic disease.”

The research appears in The Journal of Nutrition .

To understand the results of the study and provide actionable advice, Medical News Today contacted several experts for input, none of whom were involved in the study.

Fiber: The forgotten nutrient?

Not so long ago, people believed fiber was little more than “roughage” — it kept your bowels regular, but that was about it. Now, we understand that fiber is vital for gut health and overall health.

Our digestive system cannot break fiber down, so it passes through the majority of the digestive tract.

Once it reaches the large bowel, where most of our gut microbiome resides, the bacteria ferment it. During this process, the microbes release a range of compounds that benefit health, such as short-chain fatty acids (SCFAs).

MNT contacted Mir Ali, MD , a board certified bariatric surgeon and medical director of MemorialCare Surgical Weight Loss Center at Orange Coast Medical Center in Fountain Valley, CA. He outlined the important role of dietary fiber in health:

“A high fiber diet has a number of benefits: lower cholesterol and blood glucose; maintain regular bowel movements and overall bowel health; reduce the incidence of diverticulitis and other bowel conditions, to name a few.”

Janese Laster, MD , who is board certified in internal medicine, gastroenterology, obesity medicine, and nutrition explained:

“We know that by increasing fiber in the diet we can also change the human microbiome, help with satiation, which reduces overeating and weight gain, and create changes in metabolic health.”

She also told MNT that a diet rich in fiber can help regulate blood sugar levels, thereby reducing insulin resistance. According to Laster, SCFAs nourish the cells that line the gut but can also enter the blood and benefit the whole body.

According to Laster, when her patients increase fiber intake, “many notice improved energy, sleep, and reduced brain fog.”

However, while the benefits of a high fiber diet are clear, there are still outstanding questions. Fiber is not a monolith — there are many forms, but scientists do not know which forms impact which aspects of metabolism. The latest study investigates this question.

Types of fiber

Broadly speaking, dietary fiber can be split into two forms, both of which are important for health:

• Soluble fiber : Easily dissolves in water, producing a gel-like substance. This form of fiber can help lower blood cholesterol and glucose levels.
• Insoluble fiber : Rather than dissolve in water, it absorbs water. This form of fiber is particularly important for healthy bowel movements.

For their study, the researchers used a mouse model of obesity. The animals each received one of five types of fiber every day for 18 weeks:

1. Pectin: A soluble fiber found in fruits.
2. Beta-glucan: A soluble fiber found commonly in nature, including cereals, yeast, mushrooms, and seaweeds.
3. Wheat dextrin: a soluble fiber sold over the counter as a fiber supplement.
4. Resistant starch: A type of starch that functions similarly to fiber by avoiding digestion and being fermented in the colon.
5. Cellulose: an insoluble fiber found in plant cells.

The scientists measured the animals’ body weight, level of body fat, how much energy they used, and their glucose tolerance. They also analyzed their gut microbiome and the SCFAs they produced.

Beta-glucan, the victor

They found that all five fiber types significantly changed the animals’ gut microbiome and altered the levels of SCFAs that it produced.

However, when they looked at body weight, fat mass, and glucose tolerance, only beta-glucan provided benefits.

MNT spoke with Chris Mohr , PhD, RD, a fitness and nutrition advisor at Fortune Recommends Health. While he was not surprised that fiber improved markers of health, he was surprised that “only beta-glucan had a significant impact on gaining less body weight and improving glucose tolerance.”

“It’s interesting to see such a distinct advantage for beta-glucan over the others in this particular study,” he said.

Susan Bowerman , a registered dietitian, senior director of Worldwide Nutrition Education and Training at Herbalife, and Chair of the Herbalife Dietetic Advisory Board was also surprised by the results, “​​especially since another soluble fiber, pectin, was also studied.”

Health claims about beta-glucan

There is a body of evidence that supports beta-glucan’s benefits for heart health.

Both the U.S. Food and Drug Administration (FDA) and European Food Safety Authority (EFSA) allow food manufacturers to put heart health claims on products that contain beta-glucan.

However, its potential role in weight loss is less clear . Although the results of this study are encouraging, we must remember that what happens in a mouse does not always happen in a human.

“Human metabolism and gut microbiota are more complex,” Mohr told MNT , “and individual responses to dietary changes can vary.”

“However,” he continued, “previous human studies have shown some benefits of beta-glucan, suggesting a potential for similar outcomes, though further research is needed.”

This type of evidence may be difficult to collect and interpret. “In order to replicate this in humans,” explained Bowerman, “the study subjects would need to follow a precise diet. Even if results were demonstrated, it’s hard to say how effective beta-glucan would be in a free-living population consuming a varied diet.”

How to increase fiber intake

The influence of specific types of fiber on health will likely take some time to unpick. However, we know that a fiber-rich diet reduces disease risk and helps support a healthy weight.

We also know that around 95% of people in the U.S. do not consume enough fiber each day.

“We just don’t eat enough fruits, vegetables, beans, and whole grains, which are the richest sources,” explained Bowerman. “It’s important to include these foods on a daily basis.”

We asked the experts for advice on how to increase fiber intake.

“Eat more fruits and vegetables since they are high in fiber and provide extra nutrients,” explained Mohr. He also offered these tips:

• Choose whole grain bread, pasta, and rice more often than refined versions.
• One simple and inexpensive way to add fiber is by simply adding 1/2 cup of beans to your diet — foods like lentils, black beans, and so on.
• Swap current snacks for foods like nuts and seeds, which are fiber-rich and provide healthy fats and protein.
• Stay hydrated, as fiber works best when it absorbs water.

Because many people in the U.S. only eat a very small amount of fiber, our experts recommend increasing fiber intake slowly.

“Start slowly to avoid symptoms of bloating — don’t go from none to 25 grams per day,” said Laster.

MNT spoke with Nikky Contractor, Global R&D Leader at Amway, who said that “too much too fast can result in unwanted gastrointestinal symptoms, such as increased frequency of stools, gassiness, or bloating.”

Contractor also reminded that diversity is important: “Some scientists in the microbiome sphere have indicated that one should consume as many as 30-40 different fruits and vegetables each week to support a healthy microbiome.”

Dietary change can seem daunting and challenging, but slow, incremental changes are likely to be more achievable. They will also be more effective than the latest fad diets and dangerous weight-loss “hacks.”

While beta-glucan might one day be an evidence-based weight-loss supplement, for now, focusing on vegetables, nuts, seeds, and whole grains is a good start.