Max Pearson presents a collection of the week's Witness History interviews from the BBC World Service. Our guest is Dr Elizabeth Abbott, writer, historian and author of the book, "Sugar: A Bittersweet History".

First, we confront the dark history of sugar.

We hear how a researcher in the 1990s uncovered the unethical aspects of Sweden’s Vipeholm experiments in the 1940 which led to new recommendations for children to eat sweets just once a week.

And, how Mexico, a country which had one of the highest rates of fizzy drink consumption in the world, approved a tax on sugary soft drinks in 2013.

Then an event which shaped the second half of the last century - On 14 May 1955, the leader of the Soviet Union and Heads of State from seven European countries met to sign the Warsaw Pact.

Plus, the story of how two rival electricity pioneers, Nikola Tesla and Thomas Edison brought electricity to the world.

Finally, we hear from Finnish singer Marion Rung on winning the 1980 Intervision Song Contest, the USSR’s answer to Eurovision.

Contributors:

Dr Elin Bommenel - academic

(Photo: sugar cubes and fizzy drinks, Credit: Anthony Devlin/Press Association)