Molecule Found in Fruit and Nuts Restores Aging Immune System, New Study Finds

Could new research out of Switzerland have found a piece of the puzzle to slowing down or even reversing aging?

Pomegranates are the most abundant source of the precursors to urolithin A. New Africa/Shutterstock

Our bodies change as we age, and things we may have done effortlessly in our 20s—such as sprinting up a flight of stairs or touching our toes—become more challenging later in life. Maintenance also becomes more important to keep our bodies receptive to whatever we ask of them.

Like the rest of our body, the immune system suffers this age-related decline, making us more susceptible to infections and disease. But new research has discovered a molecule that can slow and perhaps even reverse the natural decline in immune function that happens as we age.

The findings were published in Nature Aging, and the results help us live longer—while remaining free of disease.

The Aging Immune System

The immune system is a complex network of cells, organs, and tissues that work together to protect us from internal and external threats.

Blood is one component of this vital system. There are three types of blood cells: red blood cells—which carry oxygen around the body; white blood cells, which are a crucial element of the immune system; and platelets, which have the function of stopping bleeding. All blood cells are created in the bone marrow and originate as hematopoietic stem cells.

Because of their role as the source of all blood cells, these hematopoietic stem cells are vital to a healthy, robust immune system. If these fundamental cells are compromised, it extends down the line, affecting our ability to produce the immune cells that protect us from the barrage of bacteria, viruses, and other microbes we come in contact with on a daily basis.

But, like the rest of the body, stem cells age and become less efficient over time, hindering their ability to create the immune cells we need. With this natural aging, mitochondria—the energy producers inside our cells—can fail to recycle and accumulate, making our immune systems less effective.

The accumulation of mitochondria happens because of the age-related decline of a process known as autophagy, which is the cell’s natural recycling system. Mitochondrial autophagy—mitophagy—clears out damaged or defective mitochondria, allowing the healthy ones to function more efficiently.

The Study Findings

The buildup of mitochondria is what Nicola Vannini, who holds a doctorate in oncology and experimental medicine, and his team at the University of Lausanne in Switzerland were focused on in their study. They wanted to see whether they could affect this mitochondrial accumulation—one aspect of the broader decline in the immune system over time—using a natural compound called urolithin A.

Several recent studies have demonstrated the positive effects of urolithin A in health, aging, and age-related conditions and its ability to target mitochondria and stimulate autophagy.

Researchers in the Swiss study took hematopoietic stem cells from old mice and put them in a petri dish with urolithin A for three days. They then inserted the stem cells into mice that had been exposed to lethal levels of irradiation. Had the mice been left untreated, they would have perished because of the exposure. The researchers then monitored the mice for 24 weeks.

Mr. Vannini’s team found that the irradiated mice that had been treated with old stem cells that were exposed to urolithin A recovered as quickly as mice treated with stem cells from young mice, meaning the urolithin A had restored the stem cell’s ability to make new blood cells—and the effects lasted for the entire duration of the study.

Researchers then performed a second experiment, this time feeding mice a diet enriched with urolithin A, resulting in increased hematopoietic stem-cell performance and rejuvenating the cell line with production that had declined—both of which diminish with aging.

Incredibly, not only were the hematopoietic stem cells restored, but also the older mice treated with urolithin A could fight viral infections significantly better than their untreated counterparts. The findings demonstrated a sequence of events that restored immune function. Urolithin A enhanced the mitochondrial recycling capacity, effectively restoring the hematopoietic stem cells and reviving the immune system.

The discoveries reveal the potential of urolithin A to combat the natural decline the immune system experiences with age and point to an exciting area of further study. The findings suggest that urolithin A may be able to reverse the aging process in hematopoietic stem cells and in the immune system and could lead to developments and further treatments that could help the increasing number of people with age-related health conditions, such as dementia, heart disease, type 2 diabetes, arthritis, and cancer.

Food Sources of Urolithin A

Although we aren’t able to get urolithin A directly from foods, the bacteria in our guts convert plant compounds, or polyphenols, from certain foods we eat into urolithin A.

Urolithin A is called a postbiotic—it’s made in the microbiome from the foods we eat. Foods rich in ellagitannins (ETs) and ellagic acid are the polyphenols that can be converted into urolithin A in our gut.

So what foods naturally contain the precursors needed to create urolithin A? The top five sources are pomegranates, strawberries, walnuts, raspberries, and almonds, all of which have numerous other health benefits.

(5PH/iStock)

However, according to a review published in Trends in Molecular Medicine, only 40 percent of the population can naturally convert dietary precursors into urolithin A at “meaningful levels,” meaning that a supplement may ensure that you can get therapeutic amounts. Various urolithin A supplements are available in health food shops and online, and combining them with a diet containing the above foods could ensure that you’re getting levels that maximize urolithin A’s benefits.

Final Thoughts

Urolithin A is a relatively obscure molecule that has been gaining attention lately because of an increasing number of studies showing its beneficial effects on longevity. Science is continually discovering the many ways in which the foods that nature provides are able to nourish our bodies, protect us from illness, heal us when we are sick, and even extend our lives.

(AlexeyBorodin/iStock)