Dietary restriction of lycopene for a period of one month resulted in significantly increased biomarkers of oxidative stress and bone resorption in postmenopausal women.

BACKGROUND AND OBJECTIVES

Lycopene is a carotenoid commonly found in tomatoes and tomato products which acts as an antioxidant to decrease oxidative stress and osteoporosis risk. We wanted to determine the effects of a lycopene-restricted diet on oxidative stress parameters and bone turnover markers in postmenopausal women.

SETTING

St. Michael 's Hospital, Toronto, ON, Canada. PARTICIPANTS AND STUDY DESIGN: 23 healthy postmenopausal women, 50-60 years old, provided blood samples at baseline and following a one-month lycopene-depletion period.

MEASUREMENTS

Serum samples were analyzed for carotenoids; the oxidative stress parameters protein thiols and thiobarbituric-malondialdehyde reactive substances; the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), and the bone turnover markers bone alkaline phosphatase and crosslinked N-telopeptide of type I collagen (NTx). A paired t-test was used to test for significant differences in bone turnover markers, oxidative stress parameters and antioxidant status after lycopene restriction.

RESULTS

Dietary lycopene restriction resulted in significantly decreased serum lycopene (p < 0.0001), lutein/zeaxanthin (p < 0.01), and α -/β -carotene (p < 0.05). GPx (p < 0.01), lipid and protein oxidation increased (not significant), while CAT and SOD were significantly depressed (p < 0.05 and p < 0.005, respectively). These changes coincided with significantly increased NTx (p < 0.05).

CONCLUSIONS

These findings suggest that the daily consumption of lycopene may be important as it acts as an antioxidant to decrease bone resorption in postmenopausal women and may therefore be beneficial in reducing the risk of osteoporosis.