How does what we eat affect our healthspan and longevity? It's a complex dynamic system

According to a recent study from the Butler Columbia Aging Center at Columbia University Mailman School of Public Health, the answer to a seemingly simple question — how does what we eat affect how we age — is unavoidably complex. While the majority of analyses had focused on the effects of a single nutrient on a single outcome, a traditional, unidimensional approach to understanding the effects of diet on health and aging no longer gives us the full picture. A healthy diet needs to be thought of based on the balance of ensembles of nutrients, rather than by optimizing a series of nutrients one at a time. Up until recently, little was understood about how dietary variety that occurs naturally in humans impacts aging. The journal BMC Biology has posted the findings online.

According to Alan Cohen, PhD, associate professor of environmental health sciences at Columbia Mailman School, "Our ability to understand the problem has been complicated by the fact that both nutrition and the physiology of ageing are highly complex and multidimensional, involving a high number of functional interactions." This study demonstrates once again how critical it is to go beyond "a single nutrient at a time" as the universal solution to the age-old problem of how to live a long and healthy life. Cohen also notes that the findings support a number of studies that emphasize the necessity for older adults to consume more protein in order to counteract sarcopenia and the decline in physical function that comes with age.

The researchers identified significant patterns of certain nutrients related with low biological aging by testing the effects of food consumption on physiological dysregulation in older persons using multidimensional modelling approaches. The Butler Columbia Aging Center employee Cohen noted that "our strategy gives a blueprint for future studies to examine the full complexity of the nutrition-aging landscape."

In order to assess on a large scale how nutrient intake correlates with aging, the researchers examined data from 1560 older men and women, aged 67-84, who were randomly chosen between November 2003 and June 2005 from the Montreal, Laval, or Sherbrooke areas in Quebec, Canada. These participants were re-examined annually for three years and followed over four years.

Through the integration of blood biomarkers, aging and age-related loss of homeostasis (physiological dysregulation) were quantified. The geometric framework for nutrition was utilized to analyze the impacts of diet for 19 different nutrient subclasses and macronutrients. Eight models were fitted by the researchers, each of which examined a distinct nutritional predictor, with the variables income, education, age, physical activity, number of comorbidities, sex, and current smoking status being taken into account.

There were four major trends found:

The chosen aging metric determined the ideal level of nutrient consumption. While increased protein intake enhanced or decreased several aging indicators, increased carbohydrate intake had the opposite effect;

There have been instances where nutrients at intermediate levels have performed well for a variety of outcomes (contrary to the simplistic more or less is better perspective); there is also a wide range of tolerance for nutrient intake patterns that don't stray too far from the norm (referred to as "homeostatic plateaus").

A nutrient's optimal levels frequently depend on the levels of another (e.g. vitamin E and vitamin C). Simpler analytical techniques fall short in capturing these relationships.

The research team also created an interactive application that enables users to investigate how various micronutrient combinations influence various facets of aging.

The findings of this study are in line with past experimental work in mice that demonstrated that high-protein diets may hasten aging in youth but are advantageous in old age.

"These findings must be confirmed in more settings because they are not experimental. Specific results, like the importance of vitamin E and vitamin C together, might not be replicated in other studies. However, the qualitative conclusion that there are no easy solutions for optimal nutrition is likely to hold up because it was obvious in almost all of our analyses using a wide range of methodologies and is consistent with evolutionary principles and a large body of prior research "Cohen added.

Columbia University's Mailman School of Public Health