Yes. Mega-dosing of Vitamin C, Vitamin E, or other antioxidants lead to decreased insulin sensitivity followed after exercise. (Source: too lazy to pull up, but visit longecity.org and search. Also check Google Scholar)
And OM-3s aren't antioxidants , they are actually pro-oxidants. Poly's oxidize easily. Omega 3's are good for you, but don't over do the polyunsats. Stick to Mono and saturated.