There is a general lack of knowledge regarding the absorption and tissue storage of the provitamin A carotenoid b-cryptoxanthin. The present study investigated the whole-body tissue distribution of b-cryptoxanthin in an appropriate small animal model, the Mongolian gerbil (Meriones unguiculatus), for human provitamin A carotenoid metabolism. After 5 d of carotenoid depletion, five gerbils were euthanised for baseline measurements. The remaining gerbils were placed in three weight-matched treatment groups (n 8). All the groups received 20 mg/d of b-cryptoxanthin from tangerine concentrate, while the second and third groups received an additional 20 and 40 mg/d of pure b-cryptoxanthin (CX40 and CX60), respectively, for 21 d. During the last 2 d of the study, urine and faecal samples of two gerbils from each treatment group were collected. b-Cryptoxanthin was detected in the whole blood, and in twelve of the fourteen tissues analysed. Most tissues resembled the liver, in which the concentrations of b-cryptoxanthin were significantly higher in the CX60 (17·8 (SEM 0·7) mg/organ; P¼ 0·004) and CX40 (16·2 (SEM 0·9) mg/organ; P¼ 0·006) groups than in the CX20 group (13·3 (SEM 0·4) mg/ organ). However, in intestinal tissues, the concentrations of b-cryptoxanthin increased only in the CX60 group. Despite elevated vitamin A concentrations in tissues at baseline due to pre-study diets containing high levels of vitamin A, b-cryptoxanthin maintained those vitamin A stores. These results indicate that b-cryptoxanthin is stored in many tissues, potentially suggesting that its functions are widespread.Key words: b-Cryptoxanthin: Tissue distribution: Gerbils: Carotenoids: Vitamin A: Retinol b-Cryptoxanthin is a provitamin A carotenoid found in high concentrations in tangerines, oranges, papayas and red sweet peppers (1) . In addition to its vitamin A-forming capabilities, b-cryptoxanthin may have other beneficial functions. It possesses antioxidant activity (2) , and animal studies have indicated an ability to reduce tumorigenesis in several different organs (3 -6) . Furthermore, b-cryptoxanthin has been postulated to have a role in bone formation (7) .Although it is one of the most commonly consumed carotenoids (1) , there is relatively little known about its metabolism. b-Cryptoxanthin can effectively improve long-term vitamin A status in animals (8) , and probably in humans (9) . Studies on comparisons of estimated dietary intakes with plasma concentrations have shown that b-cryptoxanthin appears to have greater bioavailability than a-and b-carotene in humans (10,11) . b-Cryptoxanthin micellerisation in the intestine has been shown to be 3-fold higher than b-carotene (12) , presumably due to its higher polarity. Also, it is more effectively dissolved in lipid droplets in the chromoplasts of fruits than carotenoids bound to the chloroplasts of green leafy vegetables (13 -15) .A whole-body assessment of b-cryptoxanthin absorption, including the testing of multiple biological tissues in response to its increased intake,...