How eating less salt can improve microbiome health

One recent study found that when people reduced the amount of sodium they consumed, their gut bacteria produced higher levels of beneficial compounds that reduce inflammation and improve metabolic health. Some experts suspect that one way a high-sodium diet contributes to hypertension is by disrupting gut microbes that help to regulate your blood pressure.

“We know from studies that even slight shifts in how much salt you’re eating can impact the microbes in the colon,” said Chris Damman, a gastroenterologist at the Digestive Health Center at the University of Washington Medical Center and the author of Gut Bites MD, a blog on gut health. Salt appears to affect the health and growth of these microbes, “and the extent to which they’re able to produce the healthy factors that help to regulate our appetite and our metabolism,” Damman said.

Most adults eat way too much sodium without even realizing it. Most of the sodium that we eat doesn’t come from table salt that we add to our foods. About 70 percent of dietary salt comes from ultra-processed and packaged foods like bread, pizza, potato chips, deli meats, canned soups and burgers. Health authorities recommend that adults consume no more than 2,300 milligrams of sodium daily — the amount in roughly one teaspoon of table salt — and yet the average American eats about 3,400 milligrams of sodium per day.

Eating that much sodium can raise your blood pressure, increasing the risk of heart attacks and strokes. But scientists have also shown that consuming excess sodium has a direct impact on your gut microbiome. Here are some of the effects of excess salt:

• Fewer healthy microbes: In small clinical trials, they have found that feeding people high-salt diets leads to sharp reductions in important gut microbes such as Lactobacillus, which plays a key role in the immune system and our levels of inflammation. Several studies in animals have documented this as well.
• More bad-acting microbes: Scientists have found in large observational studies that people who consume higher levels of sodium are more likely to harbor pathogenic bacteria in their guts.
• Less microbe diversity: Those same studies show high salt eaters tend to have less microbiome diversity, which is linked to higher rates of obesity, hypertension and other chronic diseases.
• Fewer short-chain fatty acids: Short-chain fatty acids are produced by our gut microbes, and research shows that they’re good for our metabolic health. One striking, randomized study asked 145 adults with untreated hypertension to follow a low-sodium diet or a normal diet for six weeks. The researchers found that when the participants ate less sodium, they had higher levels of short-chain fatty acids, lower blood pressure and improvements in blood vessel health compared with when they ate a higher-sodium diet. The findings suggest that when they’re provided the right diet, our gut microbes produce compounds that can help to lower blood pressure, said Haidong Zhu, the lead author of the study and a professor in the departments of medicine and family and community medicine at Augusta University in Georgia.

How to cut salt from your diet

Keep an eye out for processed foods. Ultra-processed foods almost always have more sodium than minimally processed foods like fresh fruits, vegetables, meats, poultry, eggs, fish, milk and plain yogurt. Replacing ultra-processed foods with fresh foods means you’ll invariably end up consuming less sodium.

Read labels: If you eat food in packages, get into the habit of checking for sodium content. In general, a food is considered low in sodium if it provides 5 percent or less of the daily value for sodium per serving. Conversely, a food is considered high in sodium if it contains 20 percent or more of the daily value for sodium per serving.

Look out for salt bombs. According to the federal government, most adults get about 40 percent of their sodium from nine categories of food. These include pizza, soups, deli meat sandwiches, savory snacks (chips, crackers, popcorn), burgers, burritos and tacos, poultry, pasta dishes, eggs and omelets. Look out for these foods and be aware that they might be adding excessive amounts of sodium to your diet.

Use salt substitutes: Salt isn’t inherently bad, Damman at the University of Washington said. We need salt in our diet. It’s just that we’re eating way too much of it. One way to mitigate the effects of salt on your health is to increase your potassium intake. A large meta-analysis published in April in the Annals of Internal Medicine found that people who replaced table salt with salt substitutes that contained potassium chloride and sodium chloride (instead of sodium chloride alone) were significantly less likely to die prematurely from heart disease or other causes compared with people who used regular salt. Other studies have also found that replacing regular salt with salt substitutes that contain potassium lowers blood pressure.

Eat more potassium-rich foods: Focus on adding the following potassium-rich foods to your diet: leafy greens, root potatoes, beans, lentils, chickpeas, butternut squash and fruits such as avocados, bananas, oranges, mangos, kiwis, prunes, raisins, dates and dried apricots.

Use seasoning. Instead of flavoring your food with table salt, try using garlic powder, black pepper, sesame seeds, and other herbs, spices, and seasonings instead.

Do you have a question about healthy eating? Email EatingLab@washpost.com and we may answer your question in a future column.