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SHORT COMMUNICATION

Telomere shortening in elderly people with mild cognitive impairment may

be attenuated with omega-3 fatty acid supplementation: A randomised

controlled pilot study

Nathan O’Callaghan1*

, Natalie Parletta2, Catherine M Milte

2, Bianca Benassi-Evans

1,

Michael Fenech1 and Peter RC Howe

2,3

1 Preventative Health Flagship, Commonwealth Scientific and Industrial Research

Organisation (CSIRO), Adelaide.

2Nutritional Physiology Research Centre and Sansom Institute for Health Research, School of

Health Sciences, University of South Australia

3Clinical Nutrition Research Centre, University of Newcastle

*Corresponding author: nathan.o’callaghan@csiro.au

PO Box 10041, Adelaide BC SA 5000, Australia

Phone: +61 8 8303 8867

Citation: O’Callaghan N, Parletta N, Milte CM, Benassi B, Fenech M, Petkov J, Howe PRC

(2013). Telomere shortening in elderly people with mild cognitive impairment may be

attenuated with omega-3 fatty acid supplementation: A randomised controlled pilot study.

Nutrition. doi: 10.1016/j.nut.2013.09.013

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Abstract (150 words)

Background/objectives: Excessive shortening of the telomeric ends of chromosomes is a

marker of accelerated ageing. Oxidative stress and nutritional deficiency may influence this

process. We investigated the effect of omega-3 polyunsaturated fatty acid (n-3 PUFA)

supplementation on telomeric shortening in elderly people with mild cognitive impairment

(MCI). Subjects/Methods: Thirty-three adults >65 years with MCI were randomised to

receive a supplement rich in the long-chain n-3 PUFAs EPA (1.67g EPA+0.16g DHA/day;

n=12) or DHA (1.55g DHA+0.40g EPA/day; n=12), versus n-6 PUFA linoleic acid (LA;

2.2g/day; n=9) for 6 months. Results: The intervention did not show an increase in telomere

length with treatment and there was a trend towards telomere shortening during the

intervention period. Linear mixed modelling produced a robust model although statistically

underpowered. Telomere shortening was greatest in the LA group (d=0.21) versus the DHA

(d=0.12) and EPA groups (d=.06). Increased erythrocyte DHA levels were associated with

reduced telomere shortening (r=-0.67, P=0.02) in the DHA group. Conclusions: Telomeric

shortening may be attenuated by n-3 PUFA supplementation, requiring further investigation

in larger samples.

Keywords: telomere length, omega-3 fatty acids, elderly, DHA, EPA, mild cognitive

impairment

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Telomeres are long hexamer (TTAGGG) repeats that protect the genome against

chromosomal instability and cellular senescence [1, 2]. Telomere shortening in leucocytes is

associated with cancer, cardiovascular disease and neurodegenerative disorders such as

Alzheimer’s disease in some but not all studies [3-5]. Furthermore, telomere shortening has

been associated with decreased cognitive ability and has been observed to be shorter in

people with mild cognitive impairment (MCI) [6]. It is becoming increasingly evident that

damage specific to the telomeric ends of chromosomes is one of the most critical events that

initiate genome instability leading to accelerated ageing, cognitive decline and

neurodegenerative disease.

Evidence is emerging that diet is an important variable affecting the rate of shortening of

telomeres. The long-chain omega-3 polyunsaturated fatty acids (n-3 PUFA) eicosapentaenoic

acid (EPA) and docosahexaenoic acid (DHA), found in marine algae and oily fish, are

postulated to play important roles in brain function and may assist to ameliorate cognitive

decline with ageing [7]. Relatively few studies, to date, investigated telomeric ageing in

relation to n-3 PUFAs [8, 9]. These researchers reported that higher n-3 PUFA blood levels

were associated with decreased telomere shortening over five years in a cohort of people with

stable coronary artery disease. Recently a single four month study, a randomised controlled

n-3 PUFA nutritional intervention study, reported no significant changes in telomere length

[9].

The aim of this study was to investigate whether telomere shortening would be attenuated by

supplementation with fish oils rich in docosahexaenoic acid (DHA) and/or eicosapentaenoic

acid (EPA) versus an n-6 PUFA supplement (safflower oil containing linoleic acid; LA) over

6 months in elderly people with mild cognitive impairment (MCI). Data were collected as

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part of a randomised controlled trial investigating effects of n-3 PUFAs EPA and DHA

compared with an n-6 PUFA control (linoleic acid; LA) on depressive symptoms, quality of

life, cognition and executive function in elderly people >65 years with MCI – further details

re recruitment, eligibility, screening, methodology and participant demographics can be

found in Sinn et al. (2011)[10]. Blood samples for the telomere analyses were collected in the

South Australian cohort.

Following screening for MCI, 44 eligible participants were recruited. They were randomised

to receive EPA-rich fish oil, (1.67g EPA + 0.16g DHA/day), DHA-rich fish oil (1.55g DHA

+ 0.40g EPA/day) or LA (safflower oil), providing 2.2g LA per day, for 6 months in 4

capsules daily. All researchers involved with participants, data entry or analysis and

participants were blinded to treatment conditions. Supplements were coded and labelled

independently. Eligible volunteers completed assessments at baseline and 6 months at the

University of South Australia in the morning following an overnight fast. Blood samples

were collected before volunteers were offered breakfast prior to their other assessments.

The project was approved by the Human Research Ethics Committees at the University of

South Australia. Informed, written consent was obtained from all participants. The trial was

registered as ACTRN12609000167268. Of the 44 eligible to be included in the study, a total

of 33 completed the six-month intervention with all outcome measures present (n=9 LA;

n=12 DHA; n=12 EPA)

Relative proportions of individual fatty acids in erythrocytes were assessed using a method

adapted from previously established methods, described elsewhere [10]. Absolute telomere

length was measured in whole blood by qPCR as described previously [11]. Adverse events

were few and minor, and compliance was excellent [10]. Changes in erythrocyte n-3 and n-6

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PUFA levels after the 6-month intervention corresponded to the respective treatments (i.e.

DHA levels increased in the DHA treatment group etc.) [10].

Overall, during the six month intervention telomere length shortened in all groups (figure 1);

this shortening was greatest in the LA group. Linear mixed modelling analysis showed no

statistically significant differences between groups due to lack of power. However, the model

was very robust, with 85% of the variance explained by individual subject differences. Effect

sizes (Cohen’s d) for the shortening of telomere length were 0.21 for the LA group (small

effect), 0.12 for the DHA group (very small effect), and 0.06 for the EPA group (trivial).

Changes in telomere length were significantly related to changes in erythrocyte DHA levels

(Pearson correlation r=-0.67, P=0.02) in the DHA treatment group indicating that those

individuals who demonstrated the largest increase in erythrocyte DHA levels showed the

smallest decline in telomere length over the 6-month intervention.

Some limitations of the study are the size of the study and the use of whole blood to measure

telomere length. It is known that immune cell sub populations have different proliferative

history/potential and thus have different telomere lengths. Therefore in a mixed cell

population sample, such as that used in this study, alterations within subsets proportions may

lead to the overall appearance of shortened telomeres. However, the change in aTL observed

in the present study is unlikely to be attributable to changes in lymphocyte subset ratios as

this would require large shifts in these populations.

Therefore, although underpowered to detect significant differences between treatment groups,

this study provides interesting pilot data that indicates telomere shortening may be modified

by nutritional means over a six month period. Specifically, increasing n-3 PUFA intake via

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supplementation may attenuate telomere shortening that occurs with age. These data build on

current epidemiological evidence and recent reports linking increased marine n-3 PUFA with

decreased telomere attrition [8]. Further investigation is needed to understand the effects

observed here, particularly deciphering whether telomere length is modified through an

increase in n-3 PUFA or (and/or) a decrease in n-6 PUFA.

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Acknowledgements

This work was funded, in part, by Mason Foundation. PH and NP are recipients of an ARC-

Linkage project Grant (LP0776922) in partnership with Novasel Australia entitled

‘‘Cognitive and behavioural benefits of omega-3 fatty acids across the lifespan’’. N Parletta

(formerly Sinn) is supported by NHMRC Program Grant funding (# 320860 and 631947).

We acknowledge and thank all volunteers for taking part in this study.

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Figure 1. Changes in telomere length during a 6-month intervention in elderly people

with MCI. Change in telomere length from base-line to post-intervention during the six

month intervention. Linear mixed modelling analysis showed that 85% of the variance was

explained by individual subject differences but no statistically significant differences between

groups due to lack of power. Effect sizes for the shortening of telomere length were d=0.21

for the LA group (small effect), d=0.12 for the DHA group (very small effect), and d=0.06

for the EPA group (trivial). DHA = docosahexaenoic acid treatment group; EPA =

eicosapentaenoic acid treatment group; LA= linoleic acid treatment group; aTLch = change

in absolute telomere length from baseline (kb/diploid genome).