Most commercially produced yoghurts begin life as pasteurised milk, which is inoculated with cultures of beneficial bacteria such as Lactobacillus acidophilus, Bifidobacteria or Streptococcus thermophilus. Many are then pasteurised again, which kills this beneficial bacteria. Probiotic yoghurt, however, is not pasteurised, so it still contains this live "friendly bacteria".

Many experts believe that these good bacteria can survive our stomach acids and reach the intestines, where they aid digestion by helping to break down food.

Much research has been done on other possible benefits of probiotics, including their ability to help treat diarrhoea caused by stomach bugs and antibiotics, their ability to improve lactose intolerance and possibly relieve irritable bowel symptoms. Research is continuing into whether they affect a variety of other conditions including bowel cancer, autism and eczema.

Experts are divided on how beneficial probiotics really are, so check the labels. Look for products containing lactobacillus or bifidobacterium, as these are the most resilient and are more likely to withstand the acid conditions of the stomach. Even so, only a proportion of the bacteria will survive, so in theory you need to eat a large quantity to benefit. Check additional ingredients, especially in probiotic yoghurt drinks, as many contain a lot of sugar, which can contribute to obesity and tooth decay.

All yoghurt is rich in protein and B vitamins and calcium, which is essential for strong, healthy bones and teeth. If you like yoghurt, make sure that you choose live probiotic yoghurt. Put it on top of your cereal, or for a delicious nutrient-packed pudding try it on its own with a drizzle of honey or fruit jam. It is great, too, in small pots for children's packed lunches with chopped dried fruit and a little soft brown sugar mixed through.