Apparent absorption of chlorophyll from spinach in an assay with dogs

Abstract

Abstract Chlorophylls are the most abundant plant pigments in nature. Recent studies have shown that chlorophyll derivatives can exhibit health-promoting activities, apart from their use as food and pharmaceutical colorants. Nevertheless, information regarding their absorption is almost inexistent. In the present model study with dogs the apparent absorption was calculated, based on chlorophyll content in food, minus the excreted chlorophyll, and the eventual appearance of any chlorophyll derivative in the bloodstream was investigated. Spinach was added to a commercial dog food and animals in the experimental group were held on this diet for 10 days. Chlorophylls a and b were transformed into their respective pheophytins during the G.I. passage. Beyond pheophytinization no other important degradation occurred. The apparent absorption of the chlorophyll derivatives ranged from 2.5 to 4.0%, with an average of 3.4%. In a second experiment, where dogs consumed a diet containing 10% dried spinach, no chlorophyll derivatives could be found in the peripheral blood until 150 min after consumption, which seems to evidence either their low absorption or their quick metabolization. Consequently, a low systemic exposure to chlorophylls or their derivatives is expected. Industrial relevance Chlorophylls, the most abundant pigments in green plants are gaining increasing importance in the human diet, not only as food colorants, but also as healthy food ingredients. Epidemiological studies have shown correlation between the consumption of chlorophylls and the decreased risk of colon cancer. This model study with dogs evidenced a reduced absorption, and consequently, the maintenance of high amounts of chlorophyll derivatives in the digestive tract, agrees with the proposition that these pigments may exert a local activity in the gut, concerning chemopreventive properties. This aspect seems to deserve further investigations to get a better understanding about the role of green vegetables in the human diet.