Spermidine is a natural molecule that may help older people’s immune systems work better after getting a vaccine, according to a new study.
As we age, our immune system gets slower. This makes it harder to fight infections and to build strong protection from shots. Scientists call this slowdown "immunosenescence."
Spermidine Could Support Aging ImmunityThe research was led by Dr. Katja Simon and Dr. Ghada Alsaleh. They gave a small group of seniors a daily spermidine pill for three months after their third COVID‑19 shot.
Spermidine is made inside our cells and is also found in wheat germ, mushrooms, parmesan, and cheddar cheese. Earlier work suggested the molecule helps cells clean up waste and stay healthy as we get older.
"Many older adults still respond well to vaccines," says Dr. Alsaleh. "But some do not make enough protection, even after several doses. The aging of immune cells may be the reason. Our results show spermidine might help restore some of that lost function."
Why Vaccines Work Less Well When We AgeCOVID‑19 showed how important vaccines are for preventing severe illness. Yet older adults often produce fewer antibodies and T‑cells after vaccination, a pattern also seen with flu shots.
To test spermidine, the team enrolled 40 healthy adults aged 65 and up. After their third COVID‑19 jab, participants took either six milligrams of spermidine or a placebo each day for 13 weeks.
About one‑quarter of the volunteers showed very weak antibody responses even after three doses. Their immune cells also displayed signs of aging, such as more DNA damage and markers of cellular senescence—a state where damaged cells stop working but stay in the body.
Better Antibody Levels in Some ParticipantsAmong the people who initially did not respond well, those who received spermidine showed clear improvements. They produced higher amounts of antibodies against the coronavirus and their blood neutralized several virus variants more effectively.
The study also found that spermidine lowered aging markers and increased autophagy, a natural recycling process that helps cells get rid of damaged parts.
No serious side effects were reported, and the supplement was well tolerated.
More Research Is NeededBecause only 40 participants were studied, the scientists say the findings are early clues, not definitive proof. Larger trials will be needed to confirm whether spermidine consistently improves vaccine responses and whether it works with other shots, like the seasonal flu vaccine.