A number of laboratory studies on their possible health effects have been conducted.
Laboratory studies could not be done for lack of equipment or supplies.
Beyond that, they say, its origin is difficult to pin down by laboratory study alone.
"But laboratory studies indicate that this works for several proteins."
The findings are from a new laboratory study that still needs to be extended and confirmed by studies in patients.
Laboratory studies took advantage of one basic fact about stem cells.
Laboratory studies on the plant have justified some of its uses as a medicine.
These laboratory studies have nonetheless provided some evidence of relationships between risk and sensitivity.
There are preliminary laboratory studies and one Chinese clinical trial.
He cites one laboratory study but says the evidence is not conclusive.