Over the last century most western countries have undergone a dramatic shift in the composition of their diets in which the omega-3 fatty acids that are essential to the brain have been flooded out by competing omega-6 fatty acids, mainly from industrial oils such as soya, corn, and sunflower. In the US, for example, soya oil accounted for only 0.02% of all calories available in 1909, but by 2000 it accounted for 20%. Americans have gone from eating a fraction of an ounce of soya oil a year to downing 25lbs (11.3kg) per person per year in that period. In the UK, omega-6 fats from oils such as soya, corn, and sunflower accounted for 1% of energy supply in the early 1960s, but by 2000 they were nearly 5%. These omega-6 fatty acids come mainly from industrial frying for takeaways, ready meals and snack foods such as crisps, chips, biscuits, ice-creams and from margarine. Alcohol, meanwhile, depletes omega-3s from the brain. [http://www.guardian.co.uk/politics/2006/oct/17/prisonsandprobation.ukcrime]