Healthy Diet, Healthy Aging

Pauline Anderson

November 05, 2013

Middle-aged women following a healthy Mediterranean-type diet — with an emphasis on fruits, vegetables, whole grains and fish, moderate amounts of alcohol, and little red meat — have much greater odds of healthy aging later on, a new study reports.

"In this study, women with healthier dietary patterns at midlife were 40% more likely to survive to age 70 or over free of major chronic diseases and with no impairment in physical function, cognition or mental health," said lead study author, Cécilia Samieri, PhD, Institut pour la Santé Publique et le Developpement, Université Bordeaux, France.

This new study adds to growing research on the health benefits of the Mediterranean diet recently reported. Various studies have shown that this diet may contribute to reduced fasting glucose concentrations and lipid levels in those at risk for diabetes, may lower the risk for cardiovascular events and stroke, and improve cognition.

The new study was published in the November 5 issue of Annals of Internal Medicine.

The analysis included 10,670 participants in the Nurses' Health Study, which began in 1976 when female nurses aged 30 to 55 years completed a mail-in survey. Since then, study participants have been closely followed on a regular basis.

In 1980, participants completed a food-frequency questionnaire (FFQ) that asked how often on average they consumed standard portions of various foods. This questionnaire was repeated in 1984 and 1986 and then every 4 years.

Dr. Cécilia Samieri

To assess dietary quality at midlife, researchers averaged information from the 1984 and 1986 FFQs. They calculated scores on 2 diet indexes:

  • Alternative Healthy Eating Index-2010 (AHEI-2010): This index considers greater intake of vegetables, fruits, whole grains, nuts, legumes, and polyunsaturated fatty acids (PUFAs); lower intake of sugar-sweetened beverages, red or processed meats, trans fats, and sodium; and moderate intake of alcoholic beverages. Total AHEI-2010 scores range from 0 (nonadherence) to 110 (perfect adherence).

  • Alternate Mediterranean diet (A-MeDi): Developed to assess adherence to the traditional Mediterranean diet, this index includes 9 components that are similar to those in the AHEI-2010. Total A-MeDi scores range from 0 (nonadherence) to 9 (perfect adherence).

In 1992, 1996, and 2000, participants completed the Medical Outcomes Short-Form 36 Health Survey, a questionnaire that evaluates 8 health concepts, including mental health and physical functioning. Scores from the Telephone Interview for Cognitive Status, an adaptation of the Mini-Mental State Examination, were used to evaluate cognitive health. From 1995 to 2001, a cognitive study was administered to participants aged 70 years or older.

Investigators separated "healthy" from "usual" aging on the basis of 4 health domains. Overall, 11.0% of the participants were considered healthy (and so were free of chronic diseases, such as cancers, myocardial infarction, and diabetes, and with no limitation in cognitive function, mental health, and physical function), and the remaining participants were considered usual agers.

Several health domains were typically impaired among the "usual" agers, said Dr. Samieri. "For example, 33% had both chronic diseases and limitations in cognitive, physical, or mental health; 64% had only limitations in cognitive, physical, or mental health; and 3.4% had only 1 or more chronic diseases."

The analysis revealed that greater adherence at midlife to AHEI-2010 and A-MeDi was strongly associated with greater odds of healthy aging (P for trend < .001 for AHEI-2010; P for trend = .002 for A-Medi).

For example, compared with women in the worst quintile of diet scores, women in the highest quintile of the AHEI-2010 and A-MeDi scores had 34% (95% confidence interval [CI], 9% - 66%) and 46% (95% CI, 17% - 83%) greater odds of healthy aging, respectively.

Individual Components

When they analyzed individual dietary components, researchers found statistically significant associations of greater intake of fruits (odds ratio [OR] for upper versus lower quintiles, 1.46) and alcohol (OR, 1.28), and lower intakes of sweetened beverages (OR, 1.28) and PUFAs (OR, 1.38) with healthy aging (P for trend ≤ .04).

The authors noted that they could not exclude participants with impaired cognition, mental health, and physical function in midlife, and although probably few women had severe impairments at baseline, reverse causation in these participants may still be possible. Because they didn't follow participants through to death or onset of a condition that would classify them as no longer healthy, researchers couldn't prospectively estimate risks for transitioning from healthy to usual aging. As well, measurement errors may have occurred in the assessment of dietary patterns.

Other possible limitations were that the study was observational and, because it included mostly white women, its results may not be generalizable to other populations.

Middle age is probably the most relevant period of exposure for preventing chronic conditions of aging that develop over many years.

"It's largely accepted that cumulative exposures to environmental risk factors over the lifespan are probably more important than late-life exposures to determine health in older ages," said Dr. Samieri. "Several mechanisms of age-related chronic diseases, for example, atherosclerosis in cardiac diseases, brain lesions in dementia, start in midlife."

Various researchers have reported on other newly documented health benefits of the Mediterranean diet, including the following:

The study was funded by the National Cancer Institute, National Institutes of Health. Dr. Samieri has disclosed no relevant financial relationships.

Ann Intern Med. 2013;159:584-591. Abstract

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