Longevity Briefs: Does A Diverse Diet Slow Ageing?

Longevity briefs provides a short summary of novel research in biology, medicine, or biotechnology that caught the attention of our researchers in Oxford, due to its potential to improve our health, wellbeing, and longevity.

The problem:

The expression ‘you are what you eat’ has a quite literal meaning – the food we consume determines most of the ingredients available to build all of the molecules and sustain the chemical processes within the body. What combination of ingredients gives us the best chance of living as long as possible in good health? That’s a very hard question to answer, as even a single food contains many chemicals that interact with each other and with different aspects of human biology. Regardless of what specific diet is optimal for longevity, research suggests that a healthy diet should contain a diverse range of foods. This study investigates whether said diversity is associated with slower ageing.

The discovery:

Researchers looked at data from the NHANES study (National Health and Nutrition Examination Survey), which is a large long-term survey in the US in which health and nutrition data is collected and tracked over time. The present study included 22,600 participants with an average age of 48. The researchers used various measurements such as blood pressure, cholesterol and white blood cell count and composition in order to calculate a value called phenotypic age. This can be viewed as the estimated age of an individual based on clinical markers – a phenotypic age that is greater than the individual’s actual (chronological) age suggests that they are ageing at an accelerated pace and vice versa. As a secondary measurement, the researchers also used an algorithm to estimate the rate of ageing.

After comparing biological age to the participants’ dietary diversity score (DDS), which was calculated using self-reported data concerning food groups, they found that higher DDS was associated with significantly slower phenotypic ageing. This remained true even after controlling for confounding factors such as calorie intake and socioeconomic status.

The implications:

Since this was an observational study (researchers didn’t randomly assign participants a diet and then measure the outcomes), it’s impossible to know for sure that dietary diversity caused slower phenotypic ageing. However, the researchers put forward some plausible mechanisms for how this could be the case. They observed significantly lower levels of markers for inflammation and oxidative stress in people with higher DDS. Both of these processes are thought to be important drivers of ageing and age-related disease. Another possible factor is the gut microbiome. A diverse diet is known to foster a diverse population of gut microbes, which in turn may promote healthy ageing through their interactions with human biology.

One interesting observation was that participants with higher DDS had a higher calorie intake on average, but lower BMI. The authors suggest that this was due to participants with high DDS consuming a larger volume of low-calorie plant-based foods and less animal-based foods, a diet which seems to be associated with less obesity for the same caloric intake. This raises the question of whether it is dietary diversity itself that matters, or rather the types of foods that tend to make up monotonous diets. The data used in this study did not contain information about how much of each food category participants consumed, so there is room to conduct more detailed studies. Until then, we can pretty safely say that diversifying your diet to contain more different plant-based foods is likely to delay the onset of age-related diseases and extend lifespan.