In the circulation study, researchers recruited 30 men who had, but were not being treated for, high blood pressure (essential hypertension). Scientists randomly gave a placebo or a combination of 1,000 mg of vitamin C plus 400 IU of vitamin E per day for eight weeks and at the end of the study tested and found that those who had taken the vitamins had more flexible arteries and increased blood flow from the shoulder to the elbow (brachial artery). Compared to placebo, blood-fluid (plasma) levels of antioxidants were higher in the vitamin group and as the antioxidant level increased, markers for cell damage (oxidative stress) decreased.
In the night-shift study, researchers recruited 30 healthy male and female nurses aged 20 to 45 and administered memory, mood and fatigue tests immediately before and after a three-night work shift. Nurses scored lower on all three tests after working for three nights. For the next 12 weeks, scientists randomly gave half the nurses a placebo while the other half took a combination of 40 mg of Panax ginseng extract, 4.8 mg of beta-carotene, 150 mcg of biotin, 200 mcg of folic acid, 18 mg of nicotinamide, 1.4 mg of vitamin B1, 1.6 mg of vitamin B2, 2 mg of vitamin B6, 1 mcg of vitamin B12, 60 mg of vitamin C, 200 IU of vitamin D3, 10 mg of vitamin E, 100 mg of calcium, 2 mg of copper, 10 mg of iron, 2.5 mg of manganese, 40 mg of magnesium, 50 mcg of selenium and 1 mg of zinc per day.
Doctors repeated the test-work-test cycle at six and 12 weeks and found that compared to placebo, after six weeks, the supplement group reported being calmer. After 12 weeks, the ginseng-vitamin-mineral group memorized and recalled more words and reported less fatigue than did those in the placebo group.