The Mediterranean diet — higher in vegetables, fruits, whole grains and olive oil, and lower in dairy products and meat — has long been cited for its health-promoting benefits. Researchers have new clues as to why. They found that the diet was associated with longer telomeres, the protective structures at the end of chromosomes. Shorter telomeres are associated with age-related chronic diseases and reduced life expectancy. The study, published in the journal BMJ, controlled for body mass index, smoking, physical activity, reproductive history and other factors, and found that the higher the score for adherence to the diet, the longer the telomeres.
…According to a study published, in Annals of Internal Medicine, sticking to a Mediterranean-style diet may help reduce the risk for Type 2 diabetes, even when people don’t lose weight or increase exercise levels.
…According to another study, about 30% of heart attacks, strokes and deaths from heart disease can be prevented in people at high risk if they switch to a Mediterranean diet rich in olive oil, nuts, beans, fish, fruits and vegetables, and even drink wine with meals, a large and rigorous new study has found.
…A study found that it also protects the brain. This association persisted even after controlling for almost two dozen demographic, environmental and vascular risk factors, and held true for both African-Americans and whites. People with high adherence to the diet were 19 percent less likely to be impaired
Whether the Mediterranean Diet score is actually associated with longitudinal changes in telomere length is debatable given the individual heterogeneity in age-related telomere changes. If consuming a Mediterranean diet does truly change telomere length, it raises the question how many weeks, months or years would one need to consume a Mediterranean diet for it to alter telomere length?
We need to be careful about interpreting studies on potential anti-ageing factors that use telomere length as a measure of ageing. Telomere length is often used as a biomarker of ageing in cross-sectional cohort studies, based on the principle that telomeres are shortened during each cell division cycle. However, the reverse is also true that telomeres can be restored or even elongated by the enzyme telomerase reverse transcriptase each cell division cycle. In addition, the gene expression of telomerase reverse transcriptases vary depending on cell types, and is much higher in rapidly proliferating cells. For example in embryonic stem cells telomere length is maintained despite numerous cell divisions. Furthermore, in the first 3 years of life, telomere shortening in infants is more than fourfold higher than adults.
Any compound that activates telomerase – the enzyme that is responsible for maintenance of telomere length – should be tested extremely carefully in every possible way, because activation of telomerase is a well established hallmark of many cancers.
TL;DR: Telomere length is a poor marker for aging, because it varies drastically with age, in different cell types of our body, and the extent of telomere shortening depends on the initial baseline length; e.g., longer telomeres show more shortening over 5 years compared to shorter telomeres.