Decrease in serum levels of vitamin A and zeaxanthin in patients with colorectal polyp.

OBJECTIVE

Several retrospective and prospective epidemiological investigations have demonstrated that a diet rich in carotenoids could prevent the development of pre-cancerous and neoplastic lesions of the digestive tract. The aim of this examination was to analyse the correlation between colorectal polyps with different histological classifications and serum carotenoid levels.

METHODS

A 10 ml blood sample was taken from all of the patients after the colonoscopic diagnosis. The serum levels of vitamin A, lutein, zeaxanthin, alpha- and beta-cryptoxanthin, alpha- and beta-carotene were measured in patients with adenomatous colorectal polyp (n = 59, 35 males, 24 females) by high-pressure liquid chromatography (HPLC) and compared with those in healthy subjects (n = 20, 10 males, 10 females). The patients were separated into four groups depending on their histological findings.

RESULTS

The serum levels of vitamin A and zeaxanthin were significantly lower in all patients with polyps (vitamin A: 0.913 +/- 0.112 micromol/l, zeaxanthin: 0.071 +/- 0.012 micromol/l) than in the control healthy group (vitamin A: 2.036 +/- 0.354 micromol/l, zeaxanthin: 0.138 +/- 0.048 micromol/l). The lowest levels were found in patients with focal adenocarcinoma in the polyp. There were no significant differences in the serum levels of other carotenoids. The serum levels of cholesterol, haemoglobin, total protein and albumin were normal in these patients.

CONCLUSIONS

There are close and inverse correlations between the serum level of carotenoids and colorectal polyps with different histological grades. The low mean carotenoid levels in patients with adenocarcinoma in the polyp indicate that deficiency of carotenoids may be an important factor in the development of colorectal cancer.