Use your loaf: choose carefully

Too much bread high in refined starches may be behind the apparent epidemic of short-sightedness in children, scientists warned last week. According to their alarming and controversial theory, insulin produced in response to rapidly digested starches in modern processed breads and cereals may affect the development of the eyeball, making it abnormally long and causing poor sight.

It's not the first time that bread has come in for criticism, but the consensus from nutritionists is that it is still a valuable food that's rich in energy, low in fat and a good provider of vitamins, minerals and fibre.

Higher-fibre breads can make a particularly valuable contribution to a healthy diet, but growing scientific opinion suggests that the healthiest loaves of all are the ones with a low glycaemic index (GI) - defined as giving the least exaggerated rise in blood sugar and the lowest insulin response.

As well as the latest evidence on short sight, cardiovascular disease, obesity and diabetes have all been linked with diets rich in high GI carbohydrates.

Here's our guide to the loaves on the shelves with marks out of 10 for health (all slices are from a large medium-sliced loaf unless otherwise stated).

White, per slice: 82 calories, 0.7g fat, 0.5g fibre

White bread - including French-style baguettes - is defined as being made with flour containing 75 per cent or less of the whole grain, which is essentially just the starchy part. On its own, white bread infuses glucose into the body as quickly as pure sucrose (table sugar), but eating it with protein fillings such as ham, egg or prawns slows down the rate of glucose release. White bread isn't as high in fibre or iron as wholemeal but it is richer in calcium.5/10

Stay Fresh White, per slice: 76 calories, 0.6g fat, 0.5g fibre

This is ordinary white bread with anti-mould and stabilising additives to extend the shelf life to seven days. Essentially, it's a much more chemical-laden bread than other types. 4/10

Milk Roll, per slice (small loaf): 46 calories, 0.5g fibre

This white bread has added skimmed milk which bumps up the calcium content. Gram for gram it has 45 per cent more than ordinary white bread. 6/10

Sourdough, per slice: 75 calories, 0.8g fibre

This mildly acidic white bread is made using a dough which has been left to ferment at room temperature. It is usually made with white flour, which means, nutritionally, there's nothing to choose between it and standard white varieties. 5/10

Soft Grain, per slice: 81 calories, 0.5g fat, 1.3g fibre

A white bread that contains "kibbled" (partly crushed or chopped up) grains of wheat and rye which slightly slow down the rate at which the bread releases glucose into the bloodstream. It contains as much fibre as brown bread. 7/10

Nimble, per slice (small loaf): 45 calories, 0.4g fat, 0.6g fibre

This, and Danish-style whites, provide just over half the calories per slice of ordinary white, which makes them popular with slimmers. But while the slices weigh less, gram for gram there are actually more calories in Nimble than a standard loaf. 5/10

Oatmeal, per slice: 88 calories, 1.2g fibre

Made with white-bread flour with added oats. Although oats contain soluble fibre which can help lower cholesterol, there are not normally sufficient quantities in the bread to have any significant effect. Nutritionally, it rates about the same as brown but releases glucose a little more slowly. 7/10

Rye/pumpernickel bread, per slice: 65 calories, 2.7g fibre

A healthy bread that's a good substitute for those intolerant to wheat. Heavy rye breads also have one of the least dramatic effects on blood sugar and insulin. 10/10

Ciabatta, per 1/4 loaf: 170 calories, 1.6g fibre

Ciabatta is higher in fat than other breads, but it's made with heart-healthy olive oil so it's not too bad if you can take the calorie hit. Focaccia, another Italian bread, has similar nutritional properties. 5/10

Bagel, each one: 214 calories, 1.5g fibre

One bagel has more calories than two slices of bread and produces a very high glycaemic response. Not great for breakfast (you'll feel hungry again fast) but a great food for before and after exercise when a quick glucose hit is something the body actually wants. 4/10

Seeded batch, per slice (small loaf, white): 75 calories, 0.9g fibre

Adding seeds such as sunflower or pumpkin to bread increases the fibre content and the levels of several vitamins, particularly the heart-healthy antioxidant vitamin E. It also slows digestion with the result that there's a smoother glucose release. 7/10

Soda bread, per slice (wholemeal): 88 calories, 2.6g fibre

Soda bread is made with baking powder rather than yeast, making it ideal for anyone on a yeast-free diet. Wholemeal is the healthier sort. 8/10

Pitta, per pitta (wholemeal): 122 calories, 3.1g fibre

Pitta breads don't need butter and can make a healthy sandwich alternative. They have much the same nutritional value as ordinary wholemeal or white bread depending on the type of flour used. 8/10

Naan, per 150g naan: 500 calories, 2.9g fibre

This "accompaniment" racks up 500 calories and nearly 20g fat - nearly as much as the main course of curry that you usually eat them with. 2/10

Kingsmill Whole White, per slice: 87 calories, 1.5g fibre

Made with one-third wholemeal flour and two-thirds white, so a good fibre source for children who don't like wholemeal bread. It contains almost a quarter more iron than white bread. That's important as studies have shown levels are worryingly low in many young children. 6/10

Nutribread for women, per slice: 80 calories, 1.3g fibre

This "functional food" loaf contains linseeds and soya which are rich in phytoestrogens - plant chemicals that help modulate hormonal activity. Regular phytoestrogen consumption may help ease menopausal symptoms such as hot flushes and could also decrease the risk of breast cancer, osteoporosis and heart disease. But four to six slices a day are needed for good effect. 9/10