Table I.

The strength of recommendation based on the quality of evidence available for each nutraceutical

Symbol	Quality of evidence	Explanation
++++	High	“Further research is very unlikely to change confidence in the estimate of effect.”
+++O	Moderate	“Further research is likely to have an important impact on confidence in the estimate of effect and may change the estimate.”
++OO	Low	“Further research is very likely to have an important impact on confidence in the estimate of effect and is likely to change the estimate.”
+OOO	Very low	“Any estimate of effect is very uncertain.”