Okwudiri Straightman Nwali

Move over carrots... how greens can save your eyesight: Spinach, kale and lettuce contain nitrates that reduce risk of developing glaucoma by nearly a third 

• Experts say spinach and kale can lower risk of glaucoma by nearly a third
• Harvard Medical School scientists found that people who ate a nitrate-rich diet had lower levels of primary open-angle glaucoma (POAG)
• Dietary nitrate is predominantly derived from green leafy vegetables and contributes to 80 per cent of nitrate intake

It is not just carrots that can help your eyesight.

Leafy greens such as lettuce, spinach and kale and nitrate-rich vegetables such as beetroot all lower the risk of glaucoma by nearly a third, research has found.

Glaucoma is a condition which can affect sight, usually due to build up of pressure within the eye because fluid cannot drain away.

This can damage the optic nerve and the nerve fibres from the retina. There are four types of glaucoma, which affects an estimated 500,000 Britons.

Researchers said dietary nitrate is predominately derived from green leafy vegetables, which contribute approximately 80 per cent of nitrate intake

Age, suffering from diabetes, ethnic origin and a family history of the disease can all cause the condition.

A new study found people who ate a nitrate-rich diet had lower levels of primary open-angle glaucoma (POAG), a rare condition which involves chronic or acute sudden painful build-up of pressure in the eye.

Scientists from Harvard Medical School looked at the link between diet and POAG.

Assistant professor of medicine Jae Kang said: ‘Evidence suggests that nitrate or nitrite, precursors for nitric oxide, is beneficial for blood circulation.

‘Dietary nitrate is predominately derived from green leafy vegetables, which contribute approximately 80 per cent of nitrate intake.

‘Although plasma nitrite levels or intake of specific vegetables have been associated with POAG, to our knowledge, dietary nitrate intake as a specific nutrient has not been evaluated.’ 

The researchers found that greater intake of dietary nitrate and green leafy vegetables was associated with a 20 per cent to 30 per cent lower POAG risk

The academic added: ‘Higher dietary nitrate and green leafy vegetable intake was associated with a lower POAG risk...

‘These findings could have important implications for POAG if the association of higher dietary nitrate and green leafy vegetable intake with a lower POAG risk is confirmed in observational or intervention studies.’

The study, published in the journal JAMA Ophthalmology, followed participants in the two studies who were over 40, free of POAG, and had results of eye examinations. The research looked at 63,893 women and 41,094 men.

During follow-up questioning, 1,483 incident cases of POAG were identified. The participants affected were divided into five groups dependent upon nitrate levels in their diet.

The researchers found that greater intake of dietary nitrate and green leafy vegetables was associated with a 20 per cent to 30 per cent lower POAG risk.