Xenohormesis – A process that extends life 

What is Xenohormesis?

The prefix xeno means a foreign substance or stranger and hormesis is a protective way to respond when there is mild stress in the environment. 

Xenohormesis is a biological theory that shows how plants that are stressed in the environment produce bioactive substances that increase resistance and a means to survive to the animals that ingest them (Hooper PL et al, 2010). Some of the stresses to plants include dehydration, starvation, predator invasion, intense weather changes and plant cell damage (Howitz KT, Sinclair DA, 2008). 

Process:

  1. Plants become stressed
  2. They produce bioactives in response to the stress 
  3. Animals consume the bioactives
  4. Results: health benefits and increased longevity

A special group of nutrients called polyphenols are produced when plants are moderately stressed. This causes an activation of sirtuin enzymes that have been shown to prolong the lifespan of animals. This benefit copies the same effect that calorie restriction has on the body (Baur JA et al, 2008). It is possible that sirtuin enzymes role is to respond to plant stress molecules as a gauge that there is an approaching problem in the environment.

When the xenohormetic substances are consumed, it promotes the animal’s longevity and health. It does this by activating the cell’s stress response within the animals. Therefore, various nutrients have been studied to help improve longevity by having this mechanism of action (Hooper PL et al, 2010).

Some of these xenohormesis compounds are completely nontoxic compounds  available in food such as resveratrol found in wine and quercetin available in tea, apples, and onions (Baur JA, Sinclair DA, 2006). Others include curcumin, black chokeberry, black current, dandelion and grapes (Hooper PL et al, 2010).

These polyphenols are an umbrella group of plant secondary metabolites that include various chemical classes. They consist of flavones, catechins, isoflavones, chalcones, stilbenes and anthocyanidins. Most of these bioactives are manufactured by the plants in response to stress (Baur JA, Sinclair DA, 2006).

Resveratrol acts in the same way metabolically as restricting calories from the diet activating sirtuin (SIRT2) enzymes. It has been shown that resveratrol helped to stabilize DNA and increase lifespan by 70% in a yeast strain (Chung S et al, 2010).

This observation essentially formed the foundations of the xenohormesis hypothesis, sparking interest in phytochemically activated enzyme/receptor pathways and their origin.

Resveratrol stimulates over 24 enzymes and receptors in the body and in animal and some human studies it demonstrates that it protects the heart and arteries cells against damaging changes and promotes healthy blood sugar levels (Baur JA, Sinclair DA, 2006).

Resveratrol has been shown to activate AMPK which is believed to be one of the major mechanisms of action of how it brings health to the body (Hooper PL et al, 2010). Also, resveratrol has demonstrated to activate Sirt1, which helps to increase lifespan (Duan W, 2013).

AMP-activated protein kinase (AMPK) is known as the “metabolic master switch.” Its activity has an effect in reducing the accumulation of fat within fat cells. Therefore, resveratrol provides support to blood sugar and weight management (Viollet B, Andreelli F, 2011). 

In conclusion, xenohormesis is a theory that shows how plants that are stressed in the environment produce bioactive substances that increase resistance. When animals eat these substances they improve health and longevity. Some of these substances are polyphenols found in food such as resveratrol and quercetin.