A meat-based diet containing too much acid increases diabetes risk, research has shown.
Scientists who studied a group of 66,485 women found that those with the most acidic diets were more likely to develop type 2 diabetes.
Typically, acidic foods consist of animal products, the scientists point out. On the other hand, fruits and vegetables help to neutralise acidity - even fruits such as lemons that are widely perceived as acidic.
Chronic acidosis - a condition caused by increased acidity in the blood and body tissues - reduces insulin sensitivity, the ability of the hormone insulin to regulate blood sugar.
The women were taking part in a major European study looking at cancer and nutrition.
Over a period of 14 years, 1,372 new cases of type 2 diabetes were recorded. Women whose potential renal acid load (Pral) scores were in the top 25 per cent had a 56 per cent greater risk of developing diabetes than those in the bottom 25 per cent.
Pral refers to the potential impact of certain foods on kidney and urine acid levels. Meats can have a Pral value as high as 9.5, cheeses 8 and fish 7.9.
In contrast, fruits and vegetables have negative Pral values.