With the barbecue season in full swing, it might be easy to overindulge on plates laden with meat.

If you want to live longer, though, it could be time to swap the ribs for vegetables and the chicken wings for chickpeas, particularly if you smoke or drink alcohol, a major study has found.

Scientists have discovered that a 3 per cent increase in calories from plant proteins — found in vegetables, pulses, grains, nuts and seeds — can reduce the risk of premature death by 10 per cent.

Their research, published in the journal JAMA, adds further evidence that a vegetarian diet is key to prolonging life and shows that even lean animal proteins may pose health risks.

A study of 130,000 people found