life span

As organisms age, there are many changes at the molecular and cellular levels that can accumulate and possibly have an impact on the ones who ingest the organism. A research group tested “older” and “younger” diets on the lifespan of yeast, fruit flies, and mice and found that the “old” diets shortened the life span of these organisms.


The process of growing older, or aging, is a biological process that occurs over the course of life. In animals, we can see a notable decrease in functions and marked physiological changes. However, on a smaller scale, aging results in the accumulation of damage to certain molecules, mutations, altered metabolite levels, and modified gene expression. However, there are different models and views of aging, where it is believed that overuse of organs is the main method by which aging occurs. The authors of a new study believe that molecular changes from aging could have negative effects that could be transferred when the aged organism is consumed by another.

This study, published in Science Advances, examines the possible harmful effects from eating organisms that have accumulated changes from aging. The scientists prepared an “older” and a “younger” diet for a range of different species: yeast, fruit flies, and mice. The diets were made sure to match the species’ biochemistry, in the sense that the organism and the food had similar molecules and components. Yeast was fed media, the liquid in which they grow, which was taken from a culture of younger or older yeast. Fruit flies were fed extracts of young or old fruit flies, and mice were fed diets which were in part made up of muscle from young or old deer.

The authors firstly observed that yeast grown in young media survived significantly longer compared with yeast grown in old media. This suggests that the old media contained factors that make yeast age faster. Similarly, they saw female fruit flies survived for a shorter period of time when fed an old diet. Additionally, they saw that female mice had shorter survival as well when fed an old diet compared to a young diet. They also examined the gut microbes of the mice and determined that mice fed a young diet were more similar to mice fed normal diets, and that mice fed the older diet had a more distinct composition. Overall, their findings suggest that age-related changes in diet may affect lifespan of different species.

The experiments demonstrate that environment, including diet, significantly contributes to aging and shortening life spans. This study is a first of its kind since this effect of young versus old diets has not been this closely examined before. It is unlikely we will ever be able to study the effect of eating younger versus older animals in humans, but the evidence this study provides establishes the view that diet is one of many factors that contribute to the aging process.


Written By: Branson Chen, BHSc

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