Effects of a High-CML Diet on Absorption and Excretion Levels in Healthy Adults
Condition: Healthy
Study type: Interventional

Summary: 
      The aim of this study is to evaluate the effect of carboxymethyl-lysine (CML) on the levels
      of absorption and excretion of CML, and in the microbiota of healthy adults. To achieve the
      objective, a randomized clinical trial will be carried out. Before the intervention, subjects
      will have a washout period for seven days, then they will be randomly assigned to either a
      high-CML or to a low-CML diet for 5 days. Both groups will consume the foods provided by the
      researchers at the research center. Diets for this intervention will be based on an
      isocaloric diet that will include breakfast, lunch, snacks and dinner.

      Blood samples will be taken the first day, the second day of the intervention, and after the
      five days of the intervention. Urine and fecal samples will be taken the day before the
      intervention and after the intervention. CML levels will be measured by Liquid chromatography
      tandem-mass spectrometry in serum and urine samples to evaluate the levels of absorption and
      excretion. DNA extraction from the fecal sample will be carried out by a commercial kit.
      Bacterial log10 number of copies will be determined by using q-PCR.
    

Detailed description: 
      Advanced glycation end products (AGEs) are a heterogenous group of compounds form mainly by
      the Maillard reaction. AGEs can be found endogenously and in some foods. Several AGEs have
      been characterized, but carboxymethyl-lysine (CML) is one of the most widely studied in
      foods. Several studies have demonstrated the association between advanced glycation end
      products and several pathologies. However, few studies have focused on studying the
      absorption and excretion processes of these glycation products. Therefore, the objective of
      the study is to evaluate the effect of carboxymethyl-lysine (CML) on the levels of absorption
      and excretion of CML, and in the microbiota of healthy adults. To achieve the objective, a
      randomized clinical trial will be carried out, which will consist of a 7-day washout period
      during which participants will receive general recommendations that allow them to stick to a
      diet with a low CML content, adherence to these recommendations will be evaluated through
      three dietary records. At the end of the washing period, participants will be randomly
      assigned to either a high-CML or to a low-CML diet for 5 days. Participants will receive the
      5 corresponding meals (breakfast, lunch, snacks and dinner) during the 5 days of the
      intervention, these preparations will be elaborated by a catering company with indications
      and supervision by the research group. Participants will assist to the research center to
      receive the breakfast, lunch and snacks. After lunch the subjects will receive a package
      containing a snack for mid-evening and the dinner. Adherence to the diet during the
      intervention period will be evaluated through a dietary record of foods.

      The intervention will be based on an isocaloric diet with a distribution of 55 to 63%
      carbohydrates, 12 to 15% protein, 25 to 30% lipids and less than 10% saturated fat.

      The diet with high content of CML will have twice the amount that the low diet, but with
      similar amounts of macro and micronutrients.

      A blood sample will be taken on the first day of the intervention to measure CML basal
      levels. In order to evaluate the levels of CML absorption, the serum collection will be
      performed on the second day and at the end of the intervention. To evaluate the levels of CML
      excretion 24-hours urine will be collected the day before the intervention and the day after
      the dietary intervention finished. To evaluate the effects on the microbiota subjects will
      take a fecal sample the day before and a day after the intervention. Measurement of CML in
      serum, 24-hour urine and food will be performed by Liquid chromatography tandem-mass
      spectrometry. DNA extraction from the fecal sample will be carried out by a commercial kit.
      Bacterial log10 number of copies will be determined by using q-PCR.
    

Intervention name(s): High-CML diet; Low-CML diet
Intervention type(s): Other; Other
Intervention description(s): Participants will be randomly assigned to either a high-CML or to a low-CML diet for 5 days, and they will receive the 5 corresponding meals (breakfast, lunch, snacks and dinner) during the 5 days of the intervention. These preparations will be elaborated by a catering company with indications and supervision by the research group. The intervention will be based on an isocaloric diet with a distribution of 55 to 63% carbohydrates, 12 to 15% protein, 25 to 30% lipids and less than 10% saturated fat and it macro and micronutrients will be similar in both diets. The only difference will be the CML content.; Participants will be randomly assigned to either a high-CML or to a low-CML diet for 5 days, and they will receive the 5 corresponding meals (breakfast, lunch, snacks and dinner) during the 5 days of the intervention. These preparations will be elaborated by a catering company with indications and supervision by the research group. The intervention will be based on an isocaloric diet with a distribution of 55 to 63% carbohydrates, 12 to 15% protein, 25 to 30% lipids and less than 10% saturated fat and it macro and micronutrients will be similar in both diets. The only difference will be the CML content.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Basic Science
Keywords: Advanced glycation end products; Absorption; Excretion