Spermidine is a chemical that's normally found in living tissues, where it influences a variety of biological processes. While it was recognized as important for these processes, it wasn’t necessarily considered especially interesting, since it was primarily known as a precursor to other chemicals. A recent study published in Nature Medicine, however, reveals that giving spermidine to mice significantly increases their lifespan while having a cardioprotective effect.

Spermidine is a long, straight carbon chain that incorporates three nitrogens (it belongs to a class of chemicals called polyamines). Previous work has shown that spermidine treatments could extend the lives of flies; it was hypothesized that this may be through increased recycling of cell material and regeneration of aging cells or perhaps by altering the energy metabolism of cells.

Similar studies hadn't been done in mammals, so the researchers began their study by giving young mice oral supplements of spermidine. The mice that received the oral supplementation lived significantly longer than control mice. And the mice didn’t have to start when young. Administering the same oral supplements to older mice produced a significant 10 percent increase in lifespan.

When the researchers looked at the heart tissue from mice that had received spermidine from a young age, they found fewer heart issues than control mice. They also found that spermidine supplementation reduced salt-related hypertension, ventricular hypertrophy (a thickening of the muscles the lowers the heart’s volume), and delayed the progression of heart failure. Mice that received the oral supplementation later in life showed a reversal of age-associated cardiac muscle thickening.

Detailed analysis of heart tissue also showed that spermidine supplemented mice had significantly less cardiac stiffness than controls and had enhanced diastolic properties, so their hearts pumped blood more efficiently. This finding showed that oral supplementation with spermidine reversed the otherwise inevitable deterioration of cardiac tissue that comes with age.

The tissue analysis suggested that spermidine increased the levels of a chemically related amino acid and improved nitric oxide production. Elevated levels of these two chemicals have been previously associated with reduced cardiovascular risk.

In terms of the mechanisms at work, the authors suspect that the protective effects of spermidine are due to systemic effects, like anti-inflammatory activity and lower of blood pressure. Spermidine-induced recycling of cell material and regeneration of cardiac cells are likely to play an important role in its cardiac effects. Though the authors didn’t test it, they suspect that this supplement may also alter the energy metabolism of cells and assert a protective effect in that way.

In terms of human applications, previous epidemiological studies have shown that diets rich in spermidine are linked to better cardiovascular health. Based on the findings of this study in mice, the authors recommend an intervention study in humans as a potential next step. Since the longevity and cardioprotective effects of spermidine are marked in mice, those trials are probably already in the planning stages.

Nature Medicine, 2016. DOI: 10.1038/nm.4222 (About DOIs).