* World shares set to snap 7 days of gains
* Nerves over U.S.-China talks spark selling in Asia and Europe
* German stocks underperform on Bayer jury ruling
* Dollar edges up on trade talk tension
* Graphic: World FX rates in 2019 tmsnrt.rs/2egbfVh
By Tom Wilson
LONDON, March 20 (Reuters) - World shares faced an end to their longest winning streak of the year as investors took profits on Wednesday before the U.S. Federal Reserve's policy decision, seen as offering clues to interest rate prospects over the coming year.
European bourses followed Asian peers down, putting the MSCI's gauge of stocks around the world on course to break seven days of gains, with reports of renewed tensions in U.S.-China trade talks also fraying nerves.
The Euro STOXX 600 fell 0.3 percent, with indexes in Britain and France also slightly down as investors closed positions before the Fed's decision, due at 1800 GMT. .
Germany underperformed, its bourse dragged down as chemicals group Bayer AG faced its worst day in 16 years after a second U.S. jury ruled its Roundup weedkiller caused cancer.
The U.S. central bank is expected to hold rates steady and cut the number of hikes projected for the rest of the year, signaling since early this year a "patient" approach to increasing borrowing costs.
That patience - interpreted as code for holding off on rate hikes - has come as the United States and other parts of the world begin to exhibit signs of slowing growth.
Traders expect no rate hikes this year and some are even building in bets for a cut in 2020.
"Some traders expect the Fed to be a little on the neutral side. The Fed will be optimistic - but not overly optimistic - to send a neutral but upbeat message to the market," said David Madden, an analyst at CMC Markets in London.
Also in play were concerns on rising tension in the U.S. trade negotiations, which pushed MSCI's broadest index of Asia-Pacific shares outside Japan down 0.2 percent.
Some market players said investors took money off the table after a report of U.S. concerns that China is pushing back against American demands in trade talks.
On the whole, though, many investors are holding on to hopes of a deal between Washington and Beijing, even as officials from the two sides remained locked in negotiations.
Talks are set to resume next week - the first since President Donald Trump delayed a March 1 deadline to raise tariffs on Chinese imports - in an acceleration aimed at ending an eight-month trade war between the world's two largest economies.
U.S. Trade Representative Robert Lighthizer and Treasury Secretary Steven Mnuchin plan to travel to China next week for another round of talks with Chinese Vice Premier Liu He.
"China is eager to come to an agreement so I'm not too worried," said Wang Shenshen, strategist at Tokai Tokyo Research Center. "As long as they are holding meetings, many things will work out."
Kazakhstan's tenge fell half a percent against the dollar as Kassym-Jomart Tokayev, a career diplomat fluent in Russian, English and Chinese, was sworn in as president.
Tokayev pledged to continue the policies of veteran leader Nursultan Nazarbayev, who unexpectedly resigned on Tuesday after three decades in power, and will serve out the presidential term ending in April 2020.
It was unclear whether Tokayev, the former prime minister, will run for a full term as president of the vast oil- and gas-rich country of 18 million people, adding to uncertainty for investors already facing a shift from long-term structural reforms towards populist policies.
Expectations of a more cautious Fed have dented the U.S. dollar, already under pressure this year as Fed Chairman Jerome Powell all but signaled a pause to the tightening cycle at the previous meeting.
The reports of increased tension in trade talks pushed the dollar up, with safe-haven bids in demand, though gains were slim as the Fed decision loomed.
The greenback edged up 0.1 percent against a basket of key rival currencies to 96.297, finding its footing after plumbing its lowest level since March 1 in overnight trading.
Sterling fell 0.3 percent to $1.3220 as turmoil grips Britain's exit from the European Union .
Prime Minister Theresa May will request a short delay to Brexit on Wednesday after her failure to get a divorce deal ratified, leaving the future of the Brexit divorce uncertain.
Oil prices were firm, supported by supply cuts led by producer club OPEC as well as U.S. sanctions against Iran and Venezuela, though gains were limited by concerns over global economic growth.
International Brent crude oil futures were at $67.65 a barrel by 0925 GMT, up 0.1 percent from their last close.
For Reuters Live Markets blog on European and UK stock markets, please click on: (Reporting by Tom Wilson Additional reporting by Hideyuki Sano in Tokyo Editing by David Holmes)