The question sounds heretical after thirty years of being told to eat more fruit: are we overdoing it? A dietitian talking about summer eating says that in her practice the tendency really is for people to eat too much fruit. Not because it is harmful, but because many think that anything healthy has no limit.

Nutritionist Paloma Quintana turns the question on its head, and that is where it gets interesting. Before we start blaming the fruit, she says, we should look at the rest of the plate. "Fruit looks to me like an ideal food, and what matters most is that it is fresh, seasonal and local," she explains. The key is not the number of apples, but what those apples are pushing out.

If fruit is replacing something sweeter, that is a gain. If it is replacing a whole meal, that is a loss.

Swapping breakfast biscuits for yoghurt and fruit is an improvement. Fruit instead of cake after lunch is an improvement. But fruit instead of lunch means you took in neither protein nor healthy fats that day, and that is a different story entirely.

The objection that always comes up is sugar. Fruit does contain natural sugars, but they do not arrive alone. They come with fibre, water, vitamins, minerals and antioxidants, and that completely changes how the body absorbs them. "What fruit gives in micronutrients and vitamins far outweighs those sugars," says Quintana, when talking about healthy, physically active people.

The situation is different for people with diabetes or impaired glucose metabolism. There, even natural sugar calls for more individualised control. That does not mean a ban - fruit stays healthy, but the amount and type are adjusted to the patient and on a doctor's advice.

The most provocative part of the whole conversation is the rule we all know by heart. Five portions of fruit a day, as a general recommendation, does not look accurate to Quintana. First, the original recommendation covers fruit and vegetables together, not fruit alone. Second, many read it as permission to compensate for everything else. "Five portions of fruit a day do not fix the rest of your diet," she says.

And that is the whole point. The question is not how much fruit we eat, but what is still sitting on the table beside it. The answer, as usual, is not hiding in the fruit bowl.