Commercial dietary antioxidant supplements assayed for their antioxidant activity by different methodologies

Area of Science:

• Nutritional Biochemistry
• Food Science
• Pharmacology

Background:

• Dietary supplements are widely used for their purported antioxidant benefits.
• Assessing the true antioxidant capacity of these supplements is complex.
• Variability in supplement composition necessitates reliable evaluation methods.

Purpose of the Study:

• To evaluate the in vitro antioxidant capacity of commercial dietary supplements using multiple methodologies.
• To compare the antioxidant activity across different supplements and assessment techniques.
• To express supplement dosages in terms of equivalent food/compound intake.

Main Methods:

• Antioxidant capacity was assessed using DPPH radical scavenging, methyl linoleate (MeLo) autoxidation inhibition, and LDL oxidation resistance.
• Seven commercial dietary antioxidant supplements were tested.
• Dosages were converted to "food/compound intake equivalents" (quercetin, strawberries, red wine).

Main Results:

• Significant variability in antioxidant activity was observed among supplements.
• Different methodologies yielded varying patterns of antioxidant capacity.
• The methyl linoleate autoxidation and LDL oxidation methods showed similar activity orders, with wider differences in the former.
• Calculated "food/compound intake equivalents" varied substantially depending on the assay used.

Conclusions:

• The antioxidant capacity of commercial supplements differs greatly and is method-dependent.
• Standardization of antioxidant capacity measurements for dietary supplements is essential.
• Accurate standardization will enable appropriate dosing based on individual oxidative status.