Research Findings Number 16

Research Findings Number 16

February 2008

Oily fish intake

and age-related macular degeneration

This publication summarises findings relating to fish intake and age-related macular degeneration from analyses of the seven country EUREYE study. The principal investigator for the EUREYE study was Professor Astrid Fletcher, London School of Hygiene and Tropical Medicine. Thomas Pocklington Trust provided funding to enable Dr Cristina Augood, London School of Hygiene and Tropical Medicine, to analyse the relevant dietary data in the EUREYE study.

Sight loss and blindness are common in older people and age-related macular degeneration is one of the leading causes in the developed world. The population-based EUREYE study was designed to estimate the prevalence and risk factors of age-related macular degeneration in a large sample of people aged 65 years and above in Europe.

The additional analyses examined the association of fish intake and omega-3 fatty acids with age-related macular degeneration (AMD) – specifically the sub-type neovascular AMD. Two of the most important omega-3 fatty acids are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), the main sources of which are oily cold-water fish.

The study found that:

Eating oily fish at least once a week compared with less than once a week was associated with a halving of the odds of having neovascular AMD.
There was a significant indication of a reduced risk of having neovascular AMD with increasing intake of either DHA or EPA.

Introduction

The EUREYE study is a population-based, cross-sectional study in seven European countries. A random sample of people aged 65 and over were invited to an eye examination (including a photograph of the back of the eye) and interviewed to determine risk factors (age, years of education, occupation, weight, body weight compared with size, current and past smoking habits and alcohol consumption, history of diabetes, stroke, heart attack, use of aspirin and other analgesics, lifetime sunlight exposure). A vision-related quality of life questionnaire examined the impact of AMD on people’s everyday function. Dietary intake during the previous 12 months was assessed by a food frequency questionnaire, and nutrient content was estimated using food composition tables.

Fish intake and age-related macular degeneration

The aim of this study was to investigate whether the usual intake of oily fish and DHA and EPA in the diet of European elderly people is associated with AMD.

The study found that:

Oily fish was consumed less than once a week by 64% of the study population, once a week by 25%, and twice a week or more by 12%.
Age and sex distribution was similar in all three categories of oily fish intake.
Participants with higher intakes of oily fish were more often users of omega-3 and fish oil supplements. Only 8% of the study participants used these supplements.
A high consumption of fish may be a marker for general healthy behaviour. Alcohol intake was lower in those who consumed more oily fish but smoking behaviour was similar for all categories of oily fish intake.
Heavier people tend to eat more food overall, but servings of oily fish were not related to body size as measured in this study.
Fish may contain alternative or additional potential protective agents such as vitamin D and retinol. Mean dietary intake of vitamin D, zinc and vitamin E increased significantly with weekly oily fish servings. Vitamin D was not associated with AMD once EPA or DHA had been taken into account.
Intakes of oily fish were associated with a reduced risk of neovascular AMD. Eating oily fish at least once a week compared with less than once a week was associated with a halving of the odds of having neovascular AMD. There was no association with geographic atrophy (another type of AMD) but the number of people with this type of AMD was too small to permit meaningful analyses.
Intakes of fish and marine fatty acids are highly correlated, making it difficult to disentangle the effect of fatty acids from the effect of fish as such.

Conclusion

A high usual intake of DHA or EPA was associated with a lower risk of neovascular AMD and this was a significant trend. In summary, we found in this study that as oily fish and DHA and EPA consumption increases, the risk of neovascular AMD decreases. Previous studies looking at the relationship of omega-3 fats to the prevalence of advanced AMD have generally observed a protective effect. This new study in European populations adds to this growing body of evidence and suggests that regular consumption of omega-3 fatty acids, especially from fish, protects against neovascular AMD in older individuals.

Authors

The principal investigator for the EUREYE study was Professor Astrid Fletcher, London School of Hygiene and Tropical Medicine. Co-investigators of the EUREYE study were Professors Johan Seland (Norway), Mati Rahu (Estonia), Usha Chakravarthy (Northern Ireland), Ian Young (Northern Ireland), Paulus de Jong (Netherlands), Gisele Soubrane (France), Laura Tomazzoli (Italy), Fotis Topouzis (Greece) and Graham Bentham (UK).

Thomas Pocklington Trust provided funding to enable Dr Cristina Augood, London School of Hygiene and Tropical Medicine, to analyse the data on the role of dietary omega-3 fatty acids in the EUREYE study.

How to obtain further information

A short report, in the form of an ‘Occasional Paper’ entitled

Oily fish intake, fatty acids and age-related macular degeneration

by Professor Astrid Fletcher is available from:

Thomas Pocklington Trust

5 Castle Row

Horticultural Place

London W4 4JQ

Telephone: 020 8995 0880 Email:

Web:

Copies of this report in large print, audio tape or CD, Braille and electronic format are available from Thomas Pocklington Trust.

Background on Pocklington

Thomas Pocklington Trust is the leading provider of housing, care and support services for people with sight loss in the UK. Each year we also commit around £700,000 to fund social and public health research and development projects.

Pocklington’s operations offer a range of sheltered and supported housing, residential care, respite care, day services, home care services, resource centres and community based support services.

A Positive about Disability and an Investor in People organisation, we are adopting quality assurance systems for all our services to ensure we not only maintain our quality standards, but also seek continuous improvement in line with the changing needs and expectations of our current and future service users.

We are working in partnership with local authorities, registered social landlords and other voluntary organisations to expand our range of services.

Our research and development programme aims to identify practical ways to improve the lives of people with sight loss, by improving social inclusion, independence and quality of life, improving and developing service outcomes as well as focusing on public health issues.

We are also applying our research findings by way of pilot service developments to test new service models and develop best practice.

In this publication, the terms ‘visually impaired people’, ‘blind and partially sighted people’ and ‘people with sight loss’ all refer to people who are blind or who have partial sight.

Published by Thomas Pocklington Trust

Registered Charity No. 1113729

Company Registered No. 5359336

ISBN 978-1-906464-00-4

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