Spermidine triggers rejuvenation of cells through induction of autophagy. Spermidine safeguards cell health and, as a potent inducer of autophagy, supports the cell taking care of cell debris and removal of toxic waste products.

Autophagy is the only preventive mechanism against intracellular pathogens. Clearance through autophagy is a mechanism of the innate as well as the adaptive immune system against intracellular microbes.

Spermidine is a caloric restriction mimetic. Spermidine acts as a caloric restriction mimetic with hunger inducing spermidine synthesis.
Spermidine acts as a caloric restriction mimetic with hunger inducing spermidine synthesis. Spermidine suppresses oxidative cell stress and thus protects not only mitochondria but all cells in the body. A spermidine transport system controlls spermidine concentration during periods of oxidative stress and initiates the induction of antioxidant proteins.
Spermidine enhances the level of general protein synthesis 1.5 to 2-fold. The spermidine induced increase in protein synthesis is an important factor for growth with spermidine modulating RNA structures and stabilising proteins at translational level. 
Spermidine increases longevity. A diet high in spermidine coupled with spermidine substitution is linked to longevity in humans. Individuals supplementing with a daily dose of at least 80mmol of spermidine show a substantially reduced risk of death.

The difference in risk of mortality for individuals with a spermidine uptake in der upper third and those in the lower third (less than 60mmol a day) is equal to an age reduction of 5.7 years.

The daily requirement of spermidine in healthy adults is 80mmol and 11.62mg respectively.

The amount of spermidine stored in the body usually reduces with age. 

Spermidine has an antioxidative effect. Spermidine can increase the antioxidative effect of antioxidants if the antioxidant is given before, after or simultaneously with spermidine. 

Spermidine protects from neurotoxic stress and thereby protects brain cells and memory function.

Spermidine shows anti-dementia effects. Spermidine is implicated in synaptic transmission and synaptic plasticity which are both essential for learning and memory.
Spermidine has potential neuroprotective effects in patients with Huntington’s disease.
Spermidine acts as an anti-inflammatory. Spermidine has an anti-inflammatory effect in acute and chronic inflammations. This is a result of its anti-oxidative and lysosomal stabilisation properties.
Spermidine boosts the immune system. Uptake of spermidine through the diet favours differentiation of naïve CD4-positive immune cells resulting in increased production of anti-inflammatory Treg cells. This is coupled with a simultaneous reduction in the numer of TH17 cells, a cell type crucial in the inflammatory response.
Spermidine has protective effects on liver tissue. Spermidine boosts glucose homeostasis, sensitivity to insulin and reduces build up of fat in the liver in obese individuals. 
Spermidine regulates insulin synthesis and insulin secretion. Spermidine plays an important role in the maintenance of pancreatic function and in the regulation of insulin synthesis and insulin secretion.
Spermidine provides for a good night’s sleep. Spermidine also impacts on sleep. Those with an insufficient uptake of spermidine show a prolonged circadian rhythm. This particular effect of spermidine deficiency can also be seen in elderly individuals suffering from Alzheimer’s disease.  Patients with Alzheimer’s display a 35% lower spermidine level than healthy individuals of the same age.
Spermidine has an effect on the beauty of skin, hair and nails. Spermidine improves the look and function of skin as well as hair and nails. Spermidine supports growth and regeneration of skin, hair and nails through regenerative stimulation of skin cells and skin appendages. Spermidine can counteract skin aging. In healthy human skin fibroblasts, spermidine is a potent cell activator and as a result has anti-aging effects.
Spermidine has protective and regenerative properties on joint cartilage and intervertebral discs. The function of the musculoskeletal system is supported by spermdine. Protective and regenerative effects on joint cartilage and intervertebral discs were shown. Spermidine exhibits  chondroprotective properties through histone acetyltranserase p300 which improves dysregulated autophagy and spermidine synthesis in aged and osteoathritic chondrocytes.
Spermidine increases mitochondrial activity through improved cell respiration and the resulting supply of ATP improves muscular endurance. This confirmed that spermidine results in increased muscular strength.
Spermidine has a cardioprotective effect. Spermidine has a positive effect on the heart muscle. Spermidine has cardioprotective effects, with spermidine stabilizing mitochondrial function, showing anti-inflammatory properties, preventing stem cells from aging. 
Spermidine has weight reducing properties.  In obesity related disorders such as hypertension, diseases of the cardio-vascular system, elevated levels of cholesterol and type 2 diabetes, fatty acid metabolism (lipolysis) is promoted by spermidine. Spermidine also reduces the amount of white adipose tissue and increases production of brown adipose tissue. Spermidine reduces the BMI – the ratio of body weight and body height – and also has weight reducing properties.