Yes Cinnamon,
But it has to be cassia cinnamon not ceylon.
And there's the courmarin to worry about which although negligible still concerns me.
Ironically the ceylon cinnamon- which has little effect- has hardly any.
It's a toxic substance to the liver and is found in the bark.
The good news is making a tea from it, thereby keeping the powder in the bag or sieve, gives you all the health benefits whilst retaining the bark containing courmarin.
I personally have persevered with Cinnamon as described above and it really has no effect on me unfortunately.
Whereas Fenugreek, gave me noticable results within a week.