Grape seed extract, an antioxidant-rich supplement that is a byproduct of the wine and juice industry, significantly improves both total and LDL cholesterol levels and triglyceride levels, and lowers markers of inflammation, concludes a meta-review of 15 randomized trials in the journal Phytotherapy Research. Researchers from Iran, Canada and Croatia concluded that the popular extract also improves fasting glucose levels, but has little effect on HbA1c or HDL cholesterol levels.