Adipose Tissue Accumulation of d-Limonene With the Consumption of a Lemonade Preparation Rich in d-Limonene Content

Abstract

d-Limonene is a bioactive food component found in high concentration in citrus peel oil with anticancer effects in preclinical studies of mammary carcinogenesis. Extrapolation of preclinical data to human cancer is limited, in part, by inadequate information on the oral bioavailability and tissue disposition of d-limonene in humans. As a fat-soluble compound, d-limonene is more likely to deposit in fatty tissues such as the breast. To assess disposition of d-limonene in humans, we conducted a pilot study of oral d-limonene-rich lemonade. Following a 1-wk washout period devoid of citrus, healthy adults consumed 40 oz. of freshly prepared lemonade containing 500 to 600 mg d-limonene daily for 4 wk. On the first and last consumption days, blood and buttock fat biopsy were collected. Matched preintervention and postintervention fat biopsies (n = 7), and matched preintervention and postintervention plasma samples (n = 6), were analyzed for d-limonene levels using gas chromatography and mass spectrometry. There was a significant increase in d-limonene levels in the fat biopsies after 4 wk (P = 0.009); initial levels ranged from nondetectable to 7.79 μmol/kg tissue, and postintervention levels ranged from 53.6 to 294 μmol/kg tissue. Plasma d-limonene levels increased from 0.35 to 0.72 μmol/l initially to postintervention levels of 0.54 to 1.65 μmol/l (P = 0.016). Postintervention adipose d-limonene levels were 51.0 to 195 times higher than plasma levels (P = 0.009). Our results demonstrate accumulation of d-limonene in adipose tissue after oral dosing and support additional studies of d-limonene for chemoprevention in tissues such as the breast that are comprised of a significant fat fraction.