Do you wish you could get more fiber in your diet, but it seems to irritate your digestive tract, causing bloating or constipation? It could all be down to the combination of foods you eat with it, says a study which analyzed high fiber diets rich in protein versus carbohydrates.
In this clinical study, participants were following the popular DASH diet (Dietary Approaches to Stop Hypertension, a.k.a. high blood pressure) which focuses on low sodium, low-fat dairy, fiber, fruits, and vegetables. They looked at 3 high-fiber versions of the DASH diet that were equal in calories and fiber (30 g/ day) but differed in macronutrients. One version was high in carbohydrates (making up 58% of total daily calories), while another was high in unsaturated fat (37% of daily calories), and the third version was high in protein (25% protein).
Most people who adopt a DASH diet and had little previous history of eating a high-fiber diet react to the new diet with increased bloating. This is due to the fermentation of dietary fiber in the gut which leads to increased gas production.
The groups that ate the DASH diet had a 41% increase in the chance of developing bloating over the 12-week study. The researchers found that the protein-rich, high-fiber DASH diet increased bloating more than the carbohydrate-rich, high-fiber DASH diet.
The study has some limitations because they couldn’t rule out the difference between soluble and insoluble fiber. Their version of a high-protein diet was high in protein, but it was mostly plant protein. The emphasis on beans, legumes, wheat, soy, seeds, and nuts altered the composition of the types of fiber that were eaten. To counteract the additional fiber content that the plant protein caused, the researchers reduced other high-fiber grains that were given to the other 2 groups. Therefore, it’s hard to say whether or not it was only due to the protein or if it was a combination of factors.
Be sure to talk to your doctor about how much fiber is right for you and the side effects you may be experiencing from it. It might be worth investigating if you can adjust your macronutrients when you start taking a in more fiber to reduce those unpleasant symptoms that often come with increased fiber consumption, based on this current information. It would also be interesting to see if reducing the grain content, like they did in this study, could also help reduce bloating for you.
Mingyu Zhang, Stephen P. Juraschek, Lawrence J. Appel, Pankaj Jay Pasricha, Edgar R. Miller, Noel T. Mueller. Effects of High-Fiber Diets and Macronutrient Substitution on Bloating. Clinical and Translational Gastroenterology, 2020; 1 DOI: 10.14309/ctg.0000000000000122