By Sally J. Feltner
The purpose of the study was to determine if adherence to a Mediterranean diet could maintain a longer telomere length, a biomarker of aging.Telomeres (DNA sequences) occur at the ends of chromosomes that often undergo a reduction of length each time a body cell divides. Their purpose is to prevent DNA loss to protect the cell’s integrity. Telomere length is proposed to be associated with life expectancy; i.e., shorter length suggests a shorter life and increased rate of developing chronic diseases as we age. The length of telomeres is variable and can be modified by many factors, but generally decreases with age. Since they can be modified, lifestyle factors such as diet may have some effect on the length. On the other hand, telomere length can be restored and elongated during each cell division cycle by an enzyme called telomerase which is also variable. The gene expresssion of this enzyme may also be modified by extrinsic factors.
This study involved 4676 healthy middle-aged women as a subset within the Nurses’ Health Study. They completed food frequency questionnaires and had blood drawn for telomere length analysis. The main outcome measure was to detect an association between telomere length in leukocytes (white blood cells) and self-reported adherence to the Mediterranean diet using a scoring system of the diet called Alternative Mediterranean Diet score.
The Mediterranean diet components primarily include a high intake of fruits, vegetables, nuts, legumes and whole grains along with a high intake of olive oil. It is also associated with a low intake of saturated fat in meats and dairy foods, a moderately high intake of fish and alcohol (especially wine with meals).
A positive adherence to this dietary pattern has consistently shown that there is less risk to develop chronic diseases such as heart disease, dementia, or accelerated aging.
The study also compared the Med diet to other dietary patterns such as the prudent diet (basically a low fat diet) and a so-called Western diet (e.g. the standard American diet) for their effects on leukocyte telomere length.
Greater adherence to the Mediterranean Diet was associated with a weak positive association with longer telomeres (p=0.02). The difference in telomere length for each one point change in the Alternative Mediterranean Diet score was calculated to be on average 1.5 years of aging. A three point change corresponded to an on average 4.5 years of aging. This is similar to findings when non-smokers are compared to smokers (4.6 years). These results were reported after adjustment for potential co-founders. The results showed no significant positive associations for the prudent diet (p=0.09) or Western diet (p=0.32) patterns and telomere length.
There have been other studies that associated other dietary factors with telomere length. You can read these results in a previous POST.
Strengths of the study:
- Large population size
- Detailed dietary records using a validated food frequency questionnaire and dietary score
Limitations of the study:
- It is not yet been established that telomere shortening is predictive of life expectancy and aging, so this association should be verified.
- The Nurses’ Health Study results cannot be generalized to other populations, since this group of women was predominantly of European ancestry.
- The data from food frequency questionnaires was self-reported.
This study was one of the first to suggest that telomere length variability may be partially explained by lifestyle factors. Oxidative stress and inflammation reduction may have been involved since there is evidence to support that these conditions may accelerate telomere shortening. Again, this was just one study, so a great deal more research is needed.
Source: BMJ 2014; Mediterranean diet and telomere length in Nurses’ Health Study: population based cohort study, 349:g6674