‘Natural food compound improves ageing immune system’.

A substance that prolongs life, protects against cardiovascular disease, tackles Alzheimer’s, strengthens the immune system and enhances the effect of vaccines: it sounds too good to be true. And yet these effects are attributed to a natural compound that has only recently entered the scientific limelight: spermidine.

OK, first the name: spermidine. Not something that invites you to take for breakfast. But perhaps you will be more enthusiastic in five minutes’ time.

The substance was first isolated from semen, hence the name. All unseemly similarities end there, because spermidine is a compound (polyamine) that occurs naturally in all our cells. It is also found in food. Wheat germ is the best source and it is also found in considerable quantities in natto, a fermented soya product that is popular in Japan. Other sources of spermidine include chicken liver, mature cheese, mushrooms, peas, nuts, apples, pears, broccoli and red wine. We ingest an average of 10 mg of spermidine per day * and some is formed by the microbes in our intestines.

The life-extending effect of spermidine

In 2010, a study was published indicating that life expectancy in several Asian countries is higher as the inhabitants consume more spermidine and related substances through food (source). And in 2012, Italian researchers reported that people who live to a relatively healthy old age have relatively high blood levels of spermidine (source). This does not prove a causal link between spermidine and a longer life, but it could very well be the case.

Indeed, a life-extending and protective effect of spermidine has been demonstrated in various organisms, such as yeast cells, worms, flies * and mice * * *.

Because spermidine interferes with fundamental metabolic processes that we humans share with the aforementioned (and virtually all other) organisms, it is likely that the substance also protects us against ageing and disease. Spermidine has antioxidant and anti-inflammatory properties, promotes the functioning of mitochondria (the ‘power plants’ of the cells) and improves protein metabolism (proteostasis), scientists write in the renowned scientific journal Science.

Spermidine promotes autophagy

But the most important effect of spermidine has to do with a process called autophagy. In all our cells, waste products are constantly produced which are swallowed and recycled by lysosomes, the rubbish collectors in our cells. This clearing process is called autophagy, which literally means ‘eating itself’. As we age, lysosomes start to function less well. Degradation products in the cells begin to accumulate and the cell slowly becomes poisoned from within. Decreased autophagy, resulting in the accumulation of debris in cells, is considered one of the most fundamental causes of ageing.

Good methods to promote autophagy are caloric restriction and fasting. Taking resveratrol may also help*. But above all, spermidine appears to have a central, stimulating role in autophagy*.

Spermidine improved memory and cognition

However, the level of spermidine in our tissues decreases as we age*, and this has potentially disastrous consequences. For example, a link has been found between low blood levels of spermidine and the deterioration of memory in demented elderly people*. Not so strange when you consider that faltering autophagy causes ‘alzheimer proteins’ (amyloid, tau) to accumulate in the brain. In small, preliminary experiments, taking spermidine supplements improved the faltering memory of elderly people* and the cognition of people with mild cognitive impairment*.

There is also evidence, mainly from animal studies* and population studies* , that spermidine from food and supplements protects against cardiovascular disease. In mice, extra spermidine led to a reversal of vascular ageing* .

Spermidine is important for the immune system

The decline of autophagy appears to be an important cause of the weakening defence system in the elderly. This is how it works. A crucial characteristic of our adaptive immune system is that it remembers encounters with pathogens for a long time. Vaccination makes good use of the immune system’s elephantine memory by injecting (part of) a virus that has been rendered harmless. If you come into contact with the virus years later, your immune system will immediately recognise it. They can then usually deal with it quickly.

However, as we age, not only our own memory deteriorates, but also that of important immune cells. The immune cells then no longer recognise the pathogen. This can cause a flu virus, or even a cold virus, to give an elderly person the final push to the grave.

Forgetful immune cells are also a reason why vaccines are often less successful in the elderly, the group that could now benefit most from a vaccine against Covid-19.

Spermidine and the memory of immune cells

Enter spermidine. The failing memory of the adaptive immune system is partly due to the fact that autophagy decreases in an important class of immune cells – the B lymphocytes. This causes waste products to accumulate in the cells, disrupting their function.

The results of a recent study suggest that boosting autophagy with spermidine may improve the effect of vaccines.

Blood samples from young and old people who had been vaccinated against the RS virus and the hepatitis C virus were examined. The researchers found that vaccination strongly stimulates autophagy in immune cells of young people, whereas this effect is much weaker in the immune cells of older people. They also saw that the level of spermidine in the immune cells of young people was higher than that in the immune cells of older people. When they treated old immune cells with spermidine in a test tube, the process of autophagy became as good as that of young immune cells.

‘Our work suggests that boosting autophagy may make vaccines for older people more effective,’ lead author Ghada Alsaleh said.

Of course, more research is needed, but nevertheless, increasing your spermidine level may be a reasonable choice: it is safe, has a wide range of beneficial health effects and could enhance the protective effect of a (corona) vaccine. Authors in Science do state that people with advanced cancer and kidney failure should wait for more extensive studies before taking supplements.

There are several ways to get more spermidine into your system. You will find them on page 24 of the e-guide Strengthen Your Immunity.

Text by Pim Christiaans | Life Unlimited