A handful of peanuts and a few pinches of herbs and spices could possibly give your gut a healthy boost, according to two separate studies from Penn State University in the US.

There are trillions of individual microorganisms living in the human stomach and intestines, comprising hundreds to thousands of species of bacteria, viruses, and fungi. Collectively, they are known as the gut microbiome, and their importance is so great to our health, scientists think of it as a supporting organ.

Diet, exercise, and medication are just some of the factors that can influence the makeup of a person’s gut, which means each individual’s gut community is unique.

If your gut microbiome isn’t fed and appropriately nurtured, harmful microbes can proliferate, while symbiotic ones have more trouble with tasks such as dealing with our immune system and breaking down our food.

Scientists are still trying to figure out what features mark the healthiest gut communities, but as research progresses, they are starting to get a better idea.

“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,” explains nutritional scientist Penny M. Kris-Etherton.

While we commonly think of diets in terms of their fundamentals, like greens and meats, a considerable amount of variation in our cultural and personal preferences comes down to the way we add some zing to our meals.

Kris-Etherton and her colleagues at Penn State are among the first to study the effect of herbs and spices on the composition of the human gut.

In their study, 54 adult participants at risk of cardiovascular disease took part in a four-week randomized controlled-feeding experiment.

During the trial, everyone stuck to the same general menu, which was designed to reflect the average American diet. Some participants were asked to add 0.5 grams (about 0.2 ounces) of spices to their meals, while others were asked to add 3.3 grams or 6.6 grams.

The spice blend includes cinnamon, ginger, cumin, turmeric, rosemary, oregano, basil, and thyme. A control group, meanwhile, were asked to put none of these spices on their food.

Fecal samples taken before and after the experiment reveal that diets with more spices tend to show greater bacterial diversity.

“It’s such a simple thing that people can do,” says Kris-Etherton.

“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!”

The new findings support recent research that suggests herbs and spices are a natural prebiotic that feeds healthy bacteria in the human gut.

In 2019, a randomized, placebo-controlled, double-blinded pilot study found that a 5-gram capsule of a spice blend, containing cinnamon, oregano, ginger, black pepper, and cayenne pepper, triggered changes to the gut microbiome that were seen within weeks.

In the more recent study, however, the spice blend was slightly different and was directly incorporated into participants’ daily meals.

Those who ate meals with medium and high amounts of spice, equivalent to about a 3/4 teaspoon per day and about 1 1/2 teaspoon per day, showed a greater abundance of gut bacteria called Ruminococcaceae. This family of microbes is generally found in higher numbers in healthier human adults, although its exact role in the gut is uncertain.

Those participants who ate spices in the study also showed lower numbers of proinflammatory molecules in the gut, indicating a possible anti-inflammatory effect.

More research is needed to figure out exactly which spices are affecting gut microbes and why, but that’s not the only dietary supplement that seems to boost certain gut bacteria.

A recent randomized controlled trial, also from Penn State, recently investigated the effect of peanuts on the microbiota for the first time.

The study took place over six weeks and included 50 adults all on the same daily diet. At the end of each day, after dinner but before bed, participants ate either 28 grams of dry roasted, unsalted peanuts, or they ate a small sample of cheese and crackers.

In the group snacking on nuts, as with the spices in the previous study, Ruminococcaceae bacteria were significantly more abundant in the gut of participants at the end of the study.

There’s still so much about the gut microbiome that scientists don’t understand, but for now, adding a pinch of spice to your diet probably won’t hurt – and it might even help. If nothing else, it’ll add some flavor.

The spice study was published in The Journal of Nutritionand the peanut study was published in Clinical Nutrition.

“The 360” shows you different perspectives on the day’s top stories and debates.

What’s happening

The world’s population reached an estimate 8 billion people on Tuesday, according to estimates from the United Nations.

It took just 12 years for the global population to increase from 7 billion to 8 billion, a period of unprecedented growth made possible by advances in public health, nutrition and economic development that have increased survival rates for children and allowed older generations to live longer than in the past.

“The milestone is an occasion to celebrate diversity and advancements while considering humanity’s shared responsibility for the planet,” UN Secretary-General António Guterres said.

The boom wasn’t distributed evenly around the world. Countries across Asia have accounted for the majority of the world’s growth since 2011. India alone added 180 million people and is projected to surpass China as the most populous nation sometime next year. Growth rates in most of Europe and North America have stagnated, with some countries even seeing their populations shrink.

Despite the speed with which the world added another billion people, demographers say the rate of population growth is actually slowing down. The UN projects that we’ll reach 9 billion people in 15 years and that the global population will ultimately peak at around 10.4 billion in the 2080s.

Why there’s debate

The question of how many people the Earth can sustain has been a source of heated debate for centuries. But our growing understanding of human-caused climate change has altered the stakes of that discussion in just a few years.

In the eyes of many experts, reaching what the UN is calling the “day of 8 billion” should be cause for major concern. They argue that a rapidly expanding population will only make it more difficult to reduce greenhouse gas emissions to the level that is needed to avoid the most catastrophic impacts of climate change. More people will also put extra strain on critical resources like food and water, which are primed to become more scarce amid extreme droughts and severe weather — especially in the parts of the world that are expected to grow most rapidly in the coming years. Some add that the most effective steps for reducing population growth, namely increased economic stability and improved reproductive autonomy for women, are worthy goals in and of themselves.

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But others say these concerns are unfounded. They argue that focusing on the size of the population obscures the actual causes, and potential solutions, for climate change. The biggest driver of global emissions, they say, is the rate of consumption in rich countries — not the fact that low-income nations are adding more people. Some demographers also believe that an expanding population should be celebrated because it will help developing nations thrive economically and create more opportunities for innovation, collaboration and prosperity.

Perspectives

Pessimists

There may not be enough resources to sustain so many people

“Rapid population growth also means more people vying for scarce water resources and leaves more families facing hunger as climate change increasingly impacts crop production in many parts of the world.” — Dan Ikpoyi and Chinedu Asadu, Associated Press

Billions of additional people will put an enormous strain on the climate

“The hard fact is that in an age of climate breakdown, human numbers matter. And the ecological impact of another 2-3 billion humans will be immense.” —John Vidal, Guardian

A prosperous future is impossible without a sustainable population

“For if our stated goals of protecting the environment and leaving a better society for our children are truly sincere it is incumbent on us then to summon the courage to, openly and unapologetically, call out the greatest threats to both — human overpopulation and overconsumption. ” —Robert P. Johnson, Santa Barbara Independent

We can curb population growth and advance women’s rights at the same time

“What if we could see our population peak earlier than projected and avoid ever having to know whether the planet can provide for 10 billion, 11 billion or 12 billion people? Achieving this wouldn’t necessitate inventing new technology or making massive monetary investments (relatively speaking). It would simply require making modern contraception available to everyone who wants it so that people are able to decide for themselves whether and when to become pregnant and give birth.” — Nicole Martin, San Diego Union-Tribune

The world isn’t doing enough to prepare for all these extra people

“No matter who is winning the debate about growth, we clearly aren’t planning for that growth particularly well.” — Howard V. Hendrix, San Francisco Chronicle

The most vulnerable places are also the least equipped to care for booming populations

“Often, the most vulnerable people in these countries face the greatest harm from climate change without having the resources to protect their health and environment. Population growth can deepen these inequities.” —Maureen Lichtveld, Conversation MarketWatch

Optimists

Climate change is the result of overconsumption in rich nations, not a growing population

“Consumption of the resources that lead to carbon emissions matters more to climate change than population growth on its own, and those resources are primarily consumed by a relatively small number of wealthy people around the world. Change those consumption patterns — through a mix of better efficiency and new technologies that don’t emit carbon — and there’s room enough to keep growing the population without cooking the planet.” —Bryan Walsh, Vox

We already have the tools we need to sustain billions more people

“Declining biodiversity with increasing human numbers does not have to be a foregone conclusion. There are sustainable solutions out there for energy, agriculture, and how we build things. It’s just a matter of shifting perspectives, attitudes, and policies.” —Lauren Leffer, Gizmodo

The speed of population growth matters as much as the size itself

“When economists think about it, a large population is great for many different outcomes, but do you achieve that large population in 10 years or 100 years or 1,000 years? The longer it takes to get there, you can put in place the right structures in the system that will support that population.” — Alex Ezeh, global health expert, to BBC

More people equals more opportunity

“Every new human being comes to the world not only with an empty stomach, but also a pair of hands, and, more importantly, a brain capable of intelligent thought and new knowledge creation. In the process of economic development, human beings cause a lot of environmental damage, but the new wealth and knowledge that we create during that process also allow us to become better stewards of the planet.” — Marian Tupy, The Hill

Prosperity is always worth celebrating

“No one gets through life without sorrow, struggle, and disappointment, yet it is indisputably true that life on earth keeps getting better and better. In the aggregate, human beings have never been healthier, wealthier, safer, better fed, or better educated than they are right now.” —Jeff Jacoby, Boston Globe

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