Because there is tremendous variability in manufacturing and quality control standards from company to company, choosing an effective product can be challenging.

CNN: How can I pick the healthiest brand of red yeast rice?

Heart-rate variability, says Dr Stein, is a good index of the degree of control an individual has over his autonomic nervous system (which controls many of the internal organs).

ECONOMIST: Diet and behaviour

This is nearly impossible given the variability of demand (at the mercy of fuel prices and the economy) and the limited control train operators have over costs, which continue to rise steadily.

ECONOMIST: Another humiliation for the government