If you often feel bloated after a meal, don't be too quick to blame high-fibre foods. The real culprit might surprise you.
Your gut may be rebelling because you're eating too much salt, a new study suggests.
"Sodium reduction is an important dietary intervention to reduce bloating symptoms and could be used to enhance compliance with healthful high-fibre diets," said study researcher Noel Mueller, an assistant professor at the Johns Hopkins Bloomberg School of Public Health in Baltimore.
He and his research colleagues looked at data from a large clinical trial conducted in the late 1990s known as Dietary Approaches to Stop Hypertension-Sodium, or DASH-Sodium for short.
Their conclusion: Consuming a lot of salt increases bloating, as does a healthy, high-fibre diet.
Although it's not clear exactly how salt contributes, Mueller suspects fluid retention may be the key. Eating more salt can promote water retention and make digestion less efficient, which can lead to gas and bloating, he said.
Studies in mice have shown that dietary salt can alter the makeup of gut bacteria. And that, in turn, can affect gas production in the colon, Mueller said.
"Our study suggests that selecting foods with lower sodium content, such as those that are not ultra-processed, may help relieve bloating in some people," he said.
Bloating affects as many as a third of Americans, including more than 90% of those with irritable bowel syndrome. It's a painful buildup of excess gas created as gut bacteria break down fibre during digestion.
For the current study, the researchers used findings from a 1998-1999 trial. In that trial, the DASH diet - one low in fat and high in fibre, fruits, nuts and veggies - was compared with a low-fibre eating regimen. The trial's goal was to learn how salt and other factors affected high blood pressure.
The new review found that about 41% on the high-fibre diet reported bloating, and men had a bigger problem with it than women. And diets high in salt increased the odds of bloating by 27%.
"We found that in both diets, reducing sodium intake reduced bloating symptoms," Mueller said.
The upshot is that reducing sodium can be an effective way to prevent gas - and may help people maintain a healthy, high-fibre eating regimen.
Many things can cause bloating -- lactose intolerance, coeliac disease, small intestinal bacterial overgrowth, infection or other conditions, said Samantha Heller, a senior clinical nutritionist at New York University Langone Health.
"If someone is experiencing gastrointestinal symptoms such as bloating on an ongoing basis, they should see their health care practitioner to see if the cause can be pinned down," said Heller, who wasn't involved with the study. "This way they will know how to manage the issue."
Occasional bloating is not uncommon, she added.
To help you avoid excess gas and bloating, Heller offered these tips:
- Increase physical activity.
- Limit highly processed foods, such as fast food, frozen meals, junk food and fried food.
- Increase your fluid intake, and make peppermint tea part of it. Avoid carbonated beverages.
- Eat more foods that are rich in fibre, such as vegetables, legumes and whole grains. Increase these slowly and in small portions, and be sure to increase your fluid intake at the same time.
- Have smaller meals.
The report was published recently in the American Journal of Gastroenterology.