You probably have not heard of Beta Glucan yet but you will be hearing much about it in the future. It is by far the most effective immune boosting nutritional compound.
It blows acai berries, echinacea and all others far into the dust. Better Glucan is a soluble fiber derived from barley – as such it is a food compound not a herbal derivative.
Here are a couple of videos on Beta Glucan…
NOW – do not fall for all the crap supplement companies selling 200 mg capsules – research has proven that 2-5 grams of beta glucan are required per day for a substantial immune response.
Perhaps grapefruit juice can alter this requirement (I dont know) but because beta glucan is available in western nations in bulk only to food manufacturers as an additive you will need to import it from china if you want it in therapeutic quantities.