People with dementia, a condition in which memory, learning, and behavior are compromised, have elevated levels of phospholipid hydroperoxides (PLOOH), free radical compounds that accumulate abnormally in the red blood cells (erythrocytes).  Kiyotaka Nakagawa, from Tohoku University (Japan), and colleagues enrolled 30 healthy men and women, ages 50 and 69 years, in a twelve-week long study during which each subject received either a daily dietary supplement of 6 milligrams astaxanthin – an antioxidant compound derived from algae, a daily supplement of 12 milligrams astaxanthin, or placebo (zero astaxanthin).  Subjects who consumed either astaxanthin supplement demonstrated markedly lower levels of PLOOH in their erythrocytes, with reductions in the order of about 40 and 50% in the 6 and 12 mg groups, respectively, compared with no significant change in the placebo group. The researchers conclude that: “These results suggest that astaxanthin supplementation results in improved erythrocyte antioxidant status and decreased [phospholipid hydroperoxide] levels, which may contribute to the prevention of dementia.”