POPPING a daily fish oil pill won’t save your vision, say scientists. A study found omega-3 fatty acids found in sardines, salmon, mackerel were no better than a dummy tablet of olive oil at relieving dry eyes.
For years patients and eye doctors have turned to the fish oil supplements following research suggesting they dramatically reduced the pain, sensitivity to light and itchy, stinging sensations.
“Many patients receiving omega-3 supplements did have substantial improvement in their symptoms, but just as many patients taking placebo had improvements.”
So Prof Maguire and colleagues enrolled 535 participants with at least a six month history of moderate to severe dry eye, assigning them at random to either a daily supplement of fish oil, or olive oil which acted as a placebo.
Importantly, unlike in most industry-sponsored trials, all participants were free to continue taking their previous medications for dry eye, such as artificial tears and prescription anti-inflammatory eye drops.
Study chair Dr Penny Asbell, of the Department of Ophthalmology at the Icahn School of Medicine at Mount Sinai in New York City, said: “Omega-3s are generally used as an add-on therapy.
Overall, 61 per cent of those in the omega-3 group and 54 per cent in the control group achieved at least a 10-point improvement in their symptom score.
“The results are significant and may change the way a lot of ophthalmologists and optometrists treat their patients.”
The researchers said clinicians and their patients have been inclined to try the supplements for a variety of conditions with inflammatory components, including dry eye, despite insufficient evidence establishing their effectiveness.
Added Prof Maguire: “The findings also emphasise the difficulty in judging whether a treatment really helps a particular dry eye patient.
“More than half the people taking placebo reported substantial symptom improvement during the year-long study.”
Annual sales of fish and animal-derived supplements amount to more than a $1-billion market in the United States, according to the Nutrition Business Journal.
Many formulations are sold over-the-counter, while others require a prescription or are available for purchase from a health care provider.
Dr Maryann Redford, programme officer for clinical research at the National Eye Institute in the US which funded the study, said: “The trial provides the most reliable and generalisable evidence thus far on omega-3 supplementation for dry eye disease.”
As well as medical treatments, the NHS recommends sufferers eat a healthy diet that includes omega-3 and omega-7 fats to prevent dry eye syndrome or reduce the symptoms.
In England in 2014, over 6.4 million prescription items for artificial tears, ocular lubricants, and astringents were prescribed at a cost of over £27 million.
The study published in the New England Journal of Medicine was also presented at the Annual Meeting of the American Society of Cataract and Refractive Surgery in Washington, D.C.