Which is healthier - whole wheat bread or white? Most people think the answer is whole wheat. But researchers at the Weizmann institute were surprised when they did a study comparing specially baked fresh artisanal sourdough with processed, packaged white bread. They found different people reacted differently - about half the people had a better response to the white, and the other half had a better response to the whole wheat sourdough.

Half of the study participants were assigned to eat an increased amount of the processed, white bread for a week, representing about 25 per cent of their calorie intake.

The other half was told to consume an increased amount of whole wheat sourdough. Afterwards the diets for the two groups were reversed.

The researchers monitored health effects like levels of glucose essential minerals, cholesterol and kidney and liver enzymes They also looked at markers for inflammation and tissue damage.

They say the findings are potentially important because they can help people understand which foods are a better fit for them based on their genetics and their microbiome - in other words a personalized approach to choosing a diet similar to personalized medicine for the treatment of illness.