Omega-3 fatty acids – health benefits under the stethoscope

Claims of health improvements based on consumption of Omega-3 fatty acids will be tested against the evidence in Auckland this week, as scientists gather to evaluate the latest research on the nutrients that are essential to normal body function.

Among the topics to be discussed at the nutrition symposium taking place at Massey University’s Albany Campus on Thursday, will be the role of omega-3 fatty acids in cardiovascular disease, adult cognitive heath and bone health.

Also on the agenda for discussion is the role of omega-3 fatty acids in brain development and among children as well the role of omega-3 fatty acids in treating ADHD.

In advance of the symposium, the Science Media Centre asked a selection of speakers for their expert view on the latest scientific evidence in relation to omega-3 and health.

Associate Professor Welma Stonehouse from Massey University’s Institute of Food Nutrition and Human Health in Auckland, comments on fish and a healthy heart comments:

“Coronary heart disease remains one of the leading causes of death in New Zealand. In 2008, New Zealand was ranked first for deaths from acute myocardial infarction among OECD countries. Long chain omega-3 fatty acids, found in fish and fish oil, have been shown to reduce the risk of coronary heart disease and provide a safe, effective, feasible and cost-effective strategy to protect from coronary heart disease.

“Evidence from epidemiological and randomised controlled clinical trials has shown that moderate doses of long chain omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), significantly reduce the risk of fatal coronary heart disease and sudden cardiac death. The most consistent and established effect of EPA and DHA is to lower triglyceride concentrations. Because of this effect, long chain omega-3 fatty acids have been shown to be an effective adjunct to statin treatment for improving the lipid and lipoprotein profile of patients with combined dyslipidemia.

“Current recommendations for the intake of the omega-3 fatty acids EPA + DHA are 610mg/d in men and 430mg/d in women for prevention of chronic disease; 1g/d for patients withcoronary heart disease;; 2-4g/d for patients with hypertriglyceridaemia.

“At the Nutrition Symposium on Omega-3 fatty acids I will be reviewing the current evidence that long chain omega-3 fatty acids protect against coronary heart disease and their possible mechanisms of action.”

Dr Alex Richardson is a Senior Research Fellow at the Centre for Evidence-Based Intervention, University of Oxford; a Visiting Research Fellow at the Dept of Physiology, Anatomy and Genetics, University of Oxford; and is Founder Director of Food and Behaviour Research. She comments on omega-3 fatty acids and children:

“The long-chain omega-3 fatty acids found in fish and seafood (EPA and DHA) play critical roles in normal brain development and function, but are relatively lacking from modern, western-type diets. Increasing evidence indicates that relative deficiencies in these omega-3 are unusually common in children with ADHD and/or related behavioural and learning difficulties such as dyslexia, dyspraxia and autism, and controlled treatment trials have shown that dietary supplementation with omega-3 can be of benefit in these conditions.

“Similar investigations are now focusing on the potential role of omega-3 fatty acids in the behaviour and cognitive performance of children from the general population. The latest research evidence in these areas will be reviewed and summarised, with an emphasis on its implications for both policy and practice.”

Dr Cath Conlon is a Lecturer in Human Nutrition from Massey University’s Institute of Food Nutrition and Human Health in Auckland. She comments on whether a high DHA supplement can improve cognitive function in healthy adults:

“Grey matter in the human brain is composed of 50% lipid which is predominantly made up of docosahexaenoic acid (DHA), a long chain omega-3 fatty acid. DHA is structurally and functionally integrated into the membranes of neural cells where it affects various cellular and neuronal processes.

“At the nutrition symposium on omega-3 fatty acids, I will be discussing research into whether a high DHA supplement could improve cognitive performance in young healthy adults.

“We studied 176 healthy adults aged 18 to 45 years as part of a randomised placebo controlled double blind intervention study. They received either a DHA supplement (1.16g) or placebo daily for 6 months. A series of cognitive tasks were administered to the participants at baseline and at the end of the study.

“Our study showed that DHA supplementation improved memory and speed of memory domains in healthy young adults whose normal diet was low in DHA. Gender differences were observed with regard to the type of domains affected. In women, DHA improved episodic memory and speed of episodic memory, and in men speed of working memory was improved compared to placebo.

“We found that a high DHA supplement taken over a 6-month period improved memory and speed of memory in healthy adults whose normal diet was low in omega-3 fatty acid intake.”

Dr Natalie Parletta, Research Fellow from the University of South Australia, comments on the role of omega-3 fatty acids in cognitive function and mood in the elderly:

“Around one in six elderly Australians reportedly suffered a mental health problem over the past 12 months, the most common being depression and cognitive impairment. Lifestyle risk factors that are protective against physical illness are also associated with reduced risk of mental illness, including physical activity, sleep, moderate wine consumption, not smoking, and a Mediterranean style diet characterised by fish, olive oil, legumes, vegetables and wine.

“Of interest here are the omega-3 fatty acids found in fish. Their consumption has become alarmingly low in western diets considering that they comprise critical components of our brain structure and function. Accordingly, low levels have been associated with poorer mental health across the lifespan, including depression and dementia with aging.

A number of studies have indicated benefits of omega-3 supplementation for depression, which is a risk factor for progression to dementia. To date, omega-3 intervention studies with elderly people indicate that those in early stages of cognitive impairment may be most likely to benefit from supplementation compared with elderly people who show no signs of impairment and those in whom dementia has progressed.”

Professor Marlena Kruger, from Massey University’s Institute of Food, Nutrition and Human Health in Palmerston North, comments on omega-3 fatty acids and bone health:

“There is increasing evidence that various long chain polyunsaturated fatty acids (LCPUFAs) have critical roles in regulating bone metabolism and may have therapeutic potential in the management of post-menopausal osteoporosis. Dietary LCPUFA deficiency in animals and humans results in decreased intestinal calcium absorption, reduced synthesis of bone connective tissue matrix and loss of cartilage, bone demineralisation, increased renal and arterial calcification, replacement of bone cells with adipose tissue and severe osteoporosis. Populations who habitually consume a high fish (high n-3 LCPUFA) diet, such as the Japanese and Greenland Eskimos, have a very low incidence of osteoporosis.

“Fatty acids from the diet, such as linoleic acid (sunflower oil for example) and alpha-linolenic acid (from linseed oil/ flax) are not easily converted in the human body to the long chain unsaturated fatty acids and with ageing, menopause, and various lifestyle factors such as smoking the ability decreases further. Increasing intake of omega-3 LCPUFAs, has been shown to minimise the decline in bone mass caused by menopause in women. Some studies in humans indicate that LCPUFAs can increase bone formation, affect peak bone mass in adolescents and reduce bone loss in older women as measured using bone mineral densitometry (BMD).

“In elderly women fish oil significantly reduced bone loss and improved spine BMD with 3.1% over 3 years. High intakes of oily fish is also associated with maintenance of hip BMD in men and women and data from the Women’s Health Initiative suggest that omega-3 PUFAs may decrease total bone fracture risk. The long chain PUFAs therefore seem to have a protective effect on bone especially post-menopause. However, long term intervention studies are required.”

Associate Professor Barbara Meyer from the University of Wollongong in Australia comments on intakes of omega-3 fatty acids for optimal health, comments:

“The optimal intake for omega-3 fatty acids is approximately 500mg per day. Whilst there are no data available from New Zealand, Australians are not consuming enough omega-3 fatty acids, with average intakes of less than half the recommended intakes. The easiest way to achieve the optimal intake is to consume two fish meals per week, one of which is an oily fish, like Salmon or sardines, or alternatively, fish oil supplements.”

To speak to any of these scientists, please contact the Science Media Centre on 04 499 5476.

Click here for more information on the symposium ‘Omega-3 fatty acids – health benefits under the stethoscope’, and a copy of the full programme, visit:

For a Fact Sheet on omega-3 fatty acids and brain development and function in children written by Dr Alex Richardson, registered journalists can log in to the SMC Resource Library.