After leaving the liver, the prohormone can be converted in the kidneys to the hormone form of vitamin D on a (relatively) large scale to be distributed throughout the body, or it can be converted on a small scale in local tissues.

FORBES: Vitamin D: Still More Questions Than Answers

This was a small-scale study, but Prof Nicolson says the results are on a par with those achieved by the large-scale reading recovery scheme in the early 1990s.

BBC: News | Education | Catching up with reading

Interventions that have a small impact on individuals can have huge impacts on society if the scale is large enough.

FORBES: Size Isn't Everything When Assessing Impact

By hiring more small businesses, it can help to drive growth and employment that on a large scale helps the economy overall.

FORBES: How to Improve the Economy and Beat Bureaucracy: Hire Small Businesses as Suppliers