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Molybdenum and Copper in Four Varieties of Common Bean (Phaseolus vulgaris): New Data of Potential Utility in Designing Healthy Diet for Diabetic Patients

Ojeda, Armando Gómez, Wrobel, Kazimierz, Escobosa, Alma Rosa Corrales, Elguera, Julio César Torres, Garay-Sevilla, Ma. Eugenia, Wrobel, Katarzyna
Biological trace element research 2015 v.163 no.1-2 pp. 244-254
Phaseolus vulgaris, cooking, copper, diabetic diet, dietary nutrient sources, digestive system, food frequency questionnaires, grains, healthy diet, homeostasis, models, molybdenum, patients, pinto beans, risk, toxicity, Mexico
Experimental evidence indicates that diabetic patients and individuals with impaired copper homeostasis could be at risk of molybdenum toxicity. A self-administered food frequency questionnaire revealed that in central Mexico, diabetic patients with severe complications tend to consume beans more often than individuals with less advanced disease. Four varieties of Phaseolus vulgaris were comparatively evaluated as the dietary sources of two elements; the results showed molybdenum concentration decreasing in the order peruvian > pinto > mayflower > black, whereas for copper, the order was peruvian > pinto ∼ black > mayflower. The two elements were determined in pre-soaking water, cooked legumes, and broth obtained in cooking procedure; an in vitro gut model was also applied to assess potentially bioavailable fraction of both elements in cooked beans. The results indicated that the black variety would be the healthiest bean choice for diabetic patients and individuals susceptible to Mo toxicity. Relatively low total molybdenum was found in this variety (2.9 ± 1.4 versus 4.3–10.9 μg g⁻¹in other types), element availability was also low (15 % in supernatant from enzymolysis, 24.9 % in combined broth + supernatant fractions), and the molar ratio of Cu/Mo was the highest among four types (41, versus Cu/Mo <10 in peruvian, pinto, or mayflower). Considering peruvian and pinto beans, broth elimination would help to lower molybdenum intake with marginal effect on Cu/Mo molar ratio. This recommendation would be especially important for peruvian variety, which provided 1090, 803, and 197 μg day⁻¹of molybdenum in raw grains, broth + supernatant, and supernatant, respectively (based on 100-g portion), exceeding the recommended daily allowance of 45 μg day⁻¹.