Fecal Transplants for Aging and Weight Loss

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Hippocrates said, “All disease begins in the gut.” Previously, I talked about the fecal transplants, transferring the stool of healthy people into the colons of patients suffering inflammatory bowel disease, multiple sclerosis––even psychiatric problems like depression, bipolar disorder, and alcoholism––to repopulate their gut with good bacteria in hopes of improving their conditions. What about fecal transplants for aging? Might the fountain of youth be a fountain of poop?

If you give mice with accelerated aging a fecal transplant from healthy mice, they perk up and live longer, but what about human poop? We don’t yet have human-to-human aging data, but we do have mice transplanted with fecal matter from a centenarian. Mice fed poop from a 101-year-old versus poop from a 70-year-old. Lipofuscin is an age pigment that’s widely used as a biomarker for aging, and lipofuscin accumulated significantly less in the brain tissue of centenarian poop-fed mice, raising the possibility that we will one-day be using centenarian fecal matter for anti-aging purposes and to promote healthy aging. Why bathe in the blood of virgins when you can dine on the dung of the venerable? To be continued, once human-to-human data are published.

Poop you may want to avoid is from overweight stool donors, given this case report about weight gain after a fecal transplant. A 32-year-old woman “had always been of normal weight” until she received a fecal transplant from a healthy but overweight donor (her daughter). After the transplant she became obese, gaining more than 40 pounds. “She said she felt like there was a switch inside her body,” her gastroenterologist reported. “No matter how much she ate or exercised, she couldn’t take the weight off. She’s very frustrated.”

The same thing happens in mice. Giving mice fecal pellets from an obese mouse resulted in nearly a doubling in fat mass, compared to lean mouse pellets, despite eating significantly fewer calories. This proves gut flora can play a pivotal role in obesity…in mice. What about in people?

Researchers decided to study pairs of human twins “discordant” for obesity––meaning one twin was fat, the other skinny. What would happen if you switched their microbiomes? The siblings may have been squeamish; so, the researchers reverted to mice again. Mice fed stool from the obese twin rapidly swelled in size, but not those fed from the lean twin, despite comparable calorie intakes. Cohousing the mice together prevented the weight gain; however, the lean-type bacteria jumped over to rescue the mouse fed stool from the obese twin, but—and here’s the critical point—only in the context of a healthier diet. The microbial cure only worked when the mice were fed low saturated fat, high-fiber diets, which makes sense since the lean-type bacteria appeared to be fiber feeders. “Together,” the researchers concluded, “these results…illustrate how a diet high in saturated fats and low in fruits and vegetables can select against human gut bacteria…associated with leanness.”

The results of the twin study suggest that the role of our gut flora in obesity is to just help take fuller advantage of a more healthful diet. So, if the twins had actually swapped their stool, the obese twin might have only lost weight if they combined the microbial makeover with healthier eating to aid the colonization of the better bugs. With the new bacteria on board, though, the healthier diet could have resulted in more weight loss––even eating the same number of calories. But you don’t really know until you put it to the test.

There had been previous published attempts, randomized double-blind placebo-controlled trials, showing no weight loss benefit to getting lean donor fecal transplants. But they kept people on the same crappy diets that led to obesity in the first place. Who cares if you keep putting slimming, fiber-feeding bacteria into your gut, if you don’t give them any fiber to eat? They’ll just starve and die right off. So, maybe you have to do both, pairing gut bacteria modulation with a dietary intervention. But, if you do a plant-based diet along with a transplant, and they lose a bunch of weight, how do you know if the transplant had anything to do with it? Which brings us to this study,

What they did is put people on a healthy plant-based diet, supplemented with green tea and green smoothies, until they lost about 20 pounds over six months, and grabbed a fecal sample. Then, they were randomized to spend the rest of the year constantly seeding their gut with the healthy microbiome they had achieved at maximal weight loss, or to placebo capsules. The question was, once they go back to their regular diets, would those getting the constant infusion of their own skinny poop help them keep the weight off? Yes. They found that participants who lost weight on a healthy diet and were then fed capsules containing fecal material collected during the diet period for months after the maximal weight loss, regained less weight than participants given placebo tablets. So, the plant-based diet appeared to produce the optimal fecal microbiome for preventing weight regain. But rather than eating your own plant-based poo, why not just stick with the plant-based diet?

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• Fadda HM. The route to palatable fecal microbiota transplantation. AAPS PharmSciTech. 2020;21(3):114.
• Haifer C, Paramsothy S, Leong RW. Faecal microbiota transplantation as an elixir of youth. Hepatobiliary Surg Nutr. 2020;9(4):488-489.
• Bárcena C, Valdés-Mas R, Mayoral P, et al. Healthspan and lifespan extension by fecal microbiota transplantation into progeroid mice. Nat Med. 2019;25(8):1234-1242.
• Chen Y, Zhang S, Zeng B, et al. Transplant of microbiota from long-living people to mice reduces aging-related indices and transfers beneficial bacteria. Aging (Albany NY). 2020;12(6):4778-4793.
• Alang N, Kelly CR. Weight gain after fecal microbiota transplantation. Open Forum Infect Dis. 2015;2(1):ofv004.
• Hamzelou J. Not just obesity – faecal transplants’ weird effects. New Scientist. February 11, 2015.
• Turnbaugh PJ, Ley RE, Mahowald MA, Magrini V, Mardis ER, Gordon JI. An obesity-associated gut microbiome with increased capacity for energy harvest. Nature. 2006;444(7122):1027-1031.
• Groves HE, Allen UD. Winning with poo? Fecal microbiome transplantation as an emerging strategy for the management of recurrent Clostridioides difficile infection in children. Pediatr Transplant. 2020;24(1):e13651.
• Ridaura VK, Faith JJ, Rey FE, et al. Gut microbiota from twins discordant for obesity modulate metabolism in mice. Science. 2013;341(6150):1241214.
• Walker AW, Parkhill J. Microbiology. Fighting obesity with bacteria. Science. 2013;341(6150):1069-1070.
• Rinott E, Youngster I, Yaskolka Meir A, et al. Effects of diet-modulated autologous fecal microbiota transplantation on weight regain. Gastroenterology. 2021;160(1):158-173.e10.
• Yu EW, Gao L, Stastka P, et al. Fecal microbiota transplantation for the improvement of metabolism in obesity: The FMT-TRIM double-blind placebo-controlled pilot trial. PLoS Med. 2020;17(3):e1003051.

Motion graphics by Avo Media

• aging
• animal studies
• calories
• fecal transplant
• fiber
• fruit
• green tea
• gut flora
• longevity
• microbiome
• obesity
• Plant-Based Diets
• saturated fat
• smoothies
• vegans
• vegetables
• vegetarians
• weight loss