Two recently published nutritional studies that came out of the same lab (but by slightly different teams of investigators) found that very small daily changes to your diet can increase the diversity of your gut microbial community, and this, in turn, can improve your general health. The studies specifically found that adding a teaspoon-and-a-half of dried herbs and spices to your daily diet (ref) or snacking on an ounce of peanuts at bedtime every night (ref) increases the overall biodiversity of your gut microbes.
“Research has shown that people who have a lot of different microbes have better health, and a better diet, than those who don’t have much bacterial diversity”, said nutritionist Penny Kris-Etherton, who is the Evan Pugh University Professor of Nutritional Sciences at the Pennsylvania State University who oversees the Cardiometabolic Research Lab. This lab studies the role of specific foods, nutrients, bioactives, and dietary patterns in the prevention of cardiovascular disease and type 2 diabetes.
The gut microbiome is comprised of all the different microbes that live within the intestine. These microbes include bacteria, archaea, fungi, and viruses — and even some of their genes and gene products. It is estimated there are roughly 1,000 different bacterial species in your gut that influence your metabolism and help you digest food, that outcompete harmful bacteria to occupy valuable gut real estate and thereby prevent diseases, and that help your immune system function more effectively.
A person’s daily diet impacts the diversity of their gut microbiome. For example, in a earlier study, researchers found that the daily intake of whole foods, such as almonds, walnuts, broccoli, avocados, whole grain barley and whole grain oats, could be predicted with a 70-85% accuracy simply by examining the relative abundance of 15-22 fecal gut bacteria species. These foods are all sources of dietary fiber, and they act to modulate the composition of bacterial species in the gut microbiome.
Plant foods that are rich in dietary fibers also contain a lot of polyphenols. These are a large class of structurally diverse chemicals that are usually poorly absorbed in the upper gastrointestinal tract and thus, pass into the large intestine relatively undigested, just as dietary fibers do. Once there, dietary fibers and polyphenols both become accessible to gut bacteria.
We know that herbs and spices are rich in polyphenolic compounds and thus, may influence bacterial species composition in the gut for this reason. But weirdly, no formal studies have investigated the effects of consistent, repeated exposures to culinary doses of a mix of herbs and spices on the gut microbiome.
Professor Kris-Etherton and her team decided to remedy this oversight. They designed a study where they provided a blend of 24 herbs and spices — including cinnamon, ginger, cumin, turmeric, rosemary, oregano, basil and thyme — to a group of participants who were at risk for cardiovascular disease. Three times per day, each participant ingested a capsule filled with one of three different culinary doses of spicy-herbs — about 1/8 teaspoon per day, a little more than 3/4 teaspoon per day and about 1 1/2 teaspoon per day.
After just four weeks, the researchers found an increase in gut bacteria diversity in the study participants, including an increase in Ruminococcaceae. This group of bacteria in the colon of healthy individuals is linked to healthy liver metabolism and immune function.
As you might expect, the highest doses of spicy-herbs had the greatest impact on gut biodiversity.
The second study focused on the effects of peanut consumption upon microbiome diversity. Peanuts, which actually are a legume (like peas), are currently recommended by the government as part of the nuts, seeds and soy dietary category. Although peanuts are the most commonly consumed ‘nut’ in the United States, no one has studied the effects of peanuts on the gut microbiome.
The peanut study compared the effects of snacking on 28 grams (approximately 1 ounce) of peanuts at bedtime to snacking on crackers and cheese, a higher carbohydrate snack, in adults with elevated fasting glucose. (Fasting blood sugar, indicative of diabetes, can be elevated in the morning after eating a high-carb bedtime snack.)
This study found that, after 6 weeks, participants in the peanut study had an increased abundance of Ruminococcaceae, as seen in the spicy-herbs study. Also like the spicy-herbs study, the peanut study illustrates how a small change to one’s diet can potentially deliver big benefits.
“It’s such a simple thing that people can do”, Professor Kris-Etherton said in a statement. “The average American diet is far from ideal, so I think everyone could benefit by adding herbs and spices. It’s also a way of decreasing sodium in your diet but flavoring foods in a way that makes them palatable and, in fact, delicious!”
“Taste is really a top criterion for why people choose the foods they do”, Professor Kris-Etherton added.
Research into the connection between gut microbiome and a variety of health factors including blood pressure to weight, indicates that an increase in Ruminococcaceae and in overall bacterial diversity is healthful. But of course, more research is needed to better understand all of the implications.
“We need a lot more research on the microbiome to see what its proper place is in terms of overall health.”