New Delhi, Aug 20 : A diet rich in omega-3 fatty acids is not only good for adults, but also crucial to ward off the development of shortsightedness (myopia) in children, according to a global study.

Omega-3 polyunsaturated fatty acids (??-3 PUFAs), which can only be obtained from the diet -- found predominantly in fish oils -- are thought to improve or prevent several chronic eye conditions, including dry eye disease and age-related macular degeneration.

But whether they can help ward off myopia wasn't clear, as studies to date have been experimental and haven't included people.

"This study provides the human evidence that higher dietary ??-3 PUFA intake is associated with shorter axial length and less myopic refraction, highlighting ??-3 PUFAs as a potential protective dietary factor against myopia development," said corresponding author Prof Jason C Yam, from the Chinese University of Hong Kong.

Axial length is the measurement of the eye from the cornea at the front to the retina at the back, and it is an indicator of myopia progression, while myopic refraction, also known as nearsightedness, is a refractive error where the eye focuses light in front of the retina, causing distant objects to appear blurry.

'Omega-3 fatty acids may suppress myopia by increasing blood flow through the choroid -- a vascular layer in the eye -- responsible for delivering nutrients and oxygen, and so staving off scleral hypoxia -- oxygen deficiency in the white of the eye and a key factor in the development of shortsightedness,' Yam explained.

The research published online in the British Journal of Ophthalmology also found that a high intake of saturated fats, found in foods such as butter, palm oil, and red meat, may boost the risk of myopia.

For the study, a team of researchers from China, the US, and Singapore drew on data from 1,005 children aged 6-8 years old in China.

They assessed the children's eyesight and measured their regular diet and physical activity.

In all, around a quarter of the children (276; 27.5 per cent) had myopia.

Higher dietary intake of omega-3 fatty acids was associated with a lower risk of the condition, while those with regular increased intake of saturated fats had a higher risk.

This is an observational study, and as such, can't establish causal and temporal factors, said the researchers, while acknowledging that food frequency questionnaires rely on recall and only provide a "snapshot in time" of diet.

/IANS