Here is a recent one that found none: http://www.bmj.com/content/346/bmj.f10.
When searching the lay press for antioxidants you will be flooded with unfounded claims from the nutraceutical industry.
There are now several large controlled studies where none of the nutraceuticals were found to have a discernable affect. The FDA is now reviewing claims for dietary antioxidants and I would guess that within 2 years those claims will need clinical data to support those. You can believe what you want but those of use who favor actual data have a different perspective.
Here is one from pub med. I don’t read the lay press. Been a biological scientist for a few decades. Antioxidant and co-antioxidant activity of vitamin C. The effect of vitamin C, either alone or in the presence of vitamin E or a water-soluble vitamin E analogue, upon the peroxidation of aqueous multilamellar phospholipid liposomes.
Doba T, Burton GW, Ingold KU.
Abstract
Thermally labile azo-initiators, dissolved in either the aqueous or lipid phase, have been used to generate peroxyl radicals at a known, steady rate in an aqueous dispersion of dilinoleoylphosphatidylcholine multilamellar liposomes at 37 degrees C in order to study the antioxidant behaviour of ascorbate itself and ascorbate in combination with either alpha-tocopherol or a water-soluble alpha-tocopherol analogue (TROLOX(-]. It is found that ascorbate is an effective inhibitor of peroxidations initiated in the aqueous phase, with each ascorbate terminating 0.6 radical chains (i.e., n = 0.6), but it is a very poor inhibitor of peroxidations initiated in the lipid phase. Peroxidations initiated in the lipid-phase in the presence of either alpha-tocopherol or TROLOX(-) indicate that ascorbate is an excellent synergist with both phenolic antioxidants (n = 0.4). In peroxidations initiated in the aqueous phase ascorbate acts as a co-antioxidant with TROLOX(-) (n = 0.7), but the interpretation of the approximately additive effect obtained in the presence of alpha-tocopherol is complicated by the fact that under the experimental conditions employed alpha-tocopherol alone does not give a distinct, measurable inhibition period. The latter problem is shown to be due to a non-uniform distribution of the water-soluble initiator within the liposome. Other examples of the complicating effects of non-uniform distributions of reactants in kinetic studies of the autoxidation of organic substrates dispersed in water are described.
PMID: 4005285 [PubMed - indexed for MEDLINE]