Dietary Intervention with Mediterranean or Healthy Eating Goals has Similar Effects on Serum and Colon Concentrations of Carotenoids and Fatty Acids

Little is known about dietary effect on colonic nutrient concentrations associated with preventive foods. This study observed 120 persons at increased risk of colon cancer randomized to a Mediterranean versus a Healthy Eating diet for six months. The former targeted increases in whole grains, fruits, vegetables, monounsaturated and n3 fats. Healthy Eating diet was based on Healthy People 2010 recommendations. At baseline, dietary fat and carotenoid intakes were poorly associated (Spearman ρ < 0.4) with serum and colon concentrations. Strong associations were observed between serum and colon measurements of β-cryptoxanthin (ρ = 0.58, p-value < 0.001), α-carotene (ρ = 0.48, p-value < 0.001), and β-carotene (ρ = 0.45, p-value < 0.001). After six months, the Healthy Eating arm increased serum lutein, β- and α-carotene significantly (p-value < 0.05). In the Mediterranean arm the significant increases were in serum lutein, β-cryptoxanthin, β-carotene, monounsaturated and n3 fats. A significant group-by-time interaction (p-value = 0.03) was obtained for monounsaturated fats. Colonic increases in carotenoids and n3 fats were significant only in Healthy Eating arm, while group-by-time interaction were significant for β-carotene (p-value = 0.02), and α-carotene (p-value = 0.03). Changes in colon concentrations were not significantly associated with reported dietary changes. Changes in colon and serum concentrations were strongly associated for β-cryptoxanthin (ρ = 0.56, p-value < 0.001), and α-carotene (ρ = 0.40, p-value < 0.001). The associations between colonic and serum concentrations suggest the potential utility of using serum concentration as a target in dietary interventions aimed at reducing colon cancer risk.