A study by researchers at Case Western University in the Journal of Acquired Immune Deficiency Syndromes shows that while antioxidants, including vitamins E and C, can help improve cholesterol levels in HIV-positive adults, the supplements may boost blood sugar levels, Reuters Health reports. Ten study participants with HIV-related lipodystrophy were given vitamin E, vitamin C, and N-acetylcysteine supplements twice a day for 24 weeks. At the end of the study, the participants had significantly lowered triglyceride and elevated HDL or "good" cholesterol levels, with slight improvements being recorded in overall and LDL or "bad" cholesterol levels. But insulin resistance as measured by blood sugar levels increased, and fasting glucose levels increased significantly. Lead researcher Grace McComsey said the findings were "very concerning," and that "it reminds us that we should always investigate vitamins and herbal supplements prior to their use in HIV-infected subjects. We should never assume that high doses of vitamins are safe. They are not safe until clinical studies prove them to be safe."