Telomeres, DNA sequences at the end of chromosomes that shorten as cells replicate and age, does not always correlate with chronological age, and there is evidence to suggest telomere shortening may be modifiable by lifestyle factors.
“The factors that are strongly associated with accelerated telomere shortening and dysfunction are oxidative stress and inflammation,” explained scientists from Institute of Genetics and Animal Biotechnology of the Polish Academy of Sciences in Nutrients.
“The ability of omega‐3 fatty acids to reduce these negative effects is related not only to their well‐documented beneficial effect on a number of ‘lifestyle’ diseases but also to their beneficial effects on telomere biology.
“The use of omega‐3 fatty acids to reduce accelerated telomere attrition and, consequently, counteract premature aging and reduce the risk of age‐related diseases raises high hopes.”
The aging and lifespan of normal, healthy cells are linked to the so-called telomerase shortening mechanism, which limits cells to a fixed number of divisions. During cell replication, the telomeres function by ensuring the cell's chromosomes do not fuse with each other or rearrange, which can lead to cancer.
Elizabeth Blackburn, a telomere pioneer at the University of California San Francisco, likened telomeres to the ends of shoelaces, without which the lace would unravel.
With each replication the telomeres shorten, and when the telomeres are totally consumed, the cells are destroyed (apoptosis). Telomere shortening or attrition was listed as one of the nine hallmarks of aging in a seminal paper published in Cell in 2013 by Carlos López-Otín et al.
“One factor inversely related to telomere length is chronic stress, both during the prenatal period and childhood, as well as in adult life,” wrote the Poland-based scientists in Nutrients. “Depression, smoking, obesity, and alcohol consumption also accelerate telomere attrition.
“Interestingly, dietary restriction and increasing dietary antioxidants protect against telomere shortening. In this context, omega‐3 fatty acids are important dietary compounds that, due to their biochemical properties, may affect the biology of telomeres.”
Their new review of the scientific literature included seven observational (non-interventional) studies, which indicated that, in general, omega-3 fatty acids may play a role in telomere biology. Such results, however, merely show correlation and not causation, which has led researchers to perform randomized dietary studies using omega-3 supplements.
The Poland-based researchers reported four such intervention studies, which were performed in a range of populations, including mothers and their infants, people with chronic renal impairment, older people suffering from mild cognitive impairment, and healthy, overweight, middle‐aged and elderly people. Doses used ranged from just over one gram per day to four grams per day of omega-3 fatty acids.
The data from the randomized trials were a mixed bag, with some indicating a potential benefit and others finding no effects.
The reviewers also searched the scientific literature for data from animal studies, and found three studies that showed a benefit from omega-3 supplementation of the diet.
“While the results of the presented cross‐sectional and randomized human and rodent studies are not entirely consistent, the overwhelming number of them have demonstrated the beneficial effects of omega‐3 fatty acids on telomere length,” wrote the reviewers.
Limitations and what’s next?
Despite the evidence being generally supportive of a role for omega-3 fatty acids to protect against telomere attrition, the reviewers noted that sample sizes from some studies were small, while also noting that telomere length in leukocytes, which is the main measurement used in the studies, may be different to telomere length in other tissues.
“… discrepancies in the presented results still indicate the need for a careful evaluation of the type of omega‐3 fatty acids, their origin, dose and the timing of administration, as well as age, gender, regional and ethnic diversity, and health status,” concluded the reviewers.