As modern medicine and public health have advanced, global increases in human lifespan have followed. A baby born in 1900 had an average life expectancy of 32 years, while one born in 2021 had a life expectancy of 71 years. In modern Western societies, expected lifespans are even longer. For instance, in 2022, statisticians reported life expectancies to be about 84 years in Japan, 82 years in the United Kingdom, 81 years in Canada, and 77 years in the United States. As people continue to live longer, scientists and clinicians worldwide prioritize promoting healthy aging. In other words, how can we best optimize our lifestyles to remain healthy during older age?
Recently, researchers from Harvard University, the University of Montreal, and the University of Copenhagen sought to understand how people’s dietary choices throughout adulthood impact their health in older age. They examined large sets of questionnaire data collected from over 100,000 nurses and health professionals over 3 decades, from 1986 to 2016. The healthcare professionals completed questionnaires every 4 years, which asked how frequently they consumed specific foods in the 12 months prior.
The researchers then sorted the participants’ dietary behaviors into health-promoting dietary patterns, such as the Mediterranean diet, a diet high in berry intake, and a diet low in salt intake. Next, they examined which dietary patterns were most common in participants they deemed to have aged healthily. In this study, the researchers defined healthy aging as (1) surviving to at least 70 years of age, (2) being without any major illnesses like cancer, heart disease, stroke, or neurodegenerative diseases, and (3) having no impairments in cognition, physical function, or mental health.
The researchers noticed a common theme among participants who followed health-promoting dietary patterns rich in fruits, vegetables, whole grains, unsaturated fats, nuts, and legumes, but low in trans fats, salt, and red and processed meats. These participants had much greater odds of meeting the study definition of healthy aging. One dietary pattern the researchers identified as being the most likely to lead to healthy aging is called the Alternative Health Eating Index, or AHEI. The AHEI diet was developed at the Harvard School of Public Health and promotes the intake of vegetables, fruits, whole grains, and protein from fish and poultry.
The researchers separated participants into brackets based on how closely their dietary patterns aligned with the AHEI diet. They found that participants in the closest bracket had 86% greater odds of achieving healthy aging than those in the furthest bracket. Interestingly, the researchers also found that following these health-promoting dietary patterns increased the likelihood of healthy aging even amongst smokers and participants who did not exercise much. Additionally, they found that higher intake of ultra-processed foods was associated with lower odds of healthy aging.
The researchers suggested that their study is particularly strong because of the large dataset and the long timescale over which they followed the participants. Nonetheless, they acknowledged a few limitations. For one, observational and questionnaire studies can’t account for environmental influences that survey responses don’t capture. Also, self-reported questionnaires have the possibility of biased responses. Lastly, because this population only included health professionals, they don’t know how applicable the results are to the general population. Nonetheless, this study adds to a growing body of evidence that what we eat plays an important role in impacting our health in older age.
