** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** THE DIETARY GUIDELINES FOR AMERICANS RECOMMENDATION TO CHOOSE FAT-FREE AND LOW-FAT IN PLACE OF FULL-FAT DAIRY PRODUCTS HAS BECOME HIGHLY CONTROVERSIAL, AS HAS THE POTENTIAL MITIGATING EFFECT OF FERMENTATION. WITHIN THIS CONTEXT THE QUESTION HAS ARISEN AS TO WHETHER THE CURRENT GUIDANCE REGARDING DAIRY PRODUCTS FOR HEART DISEASE RISK REDUCTION SHOULD BE MODIFIED. TO CLARIFY THIS ISSUE A STUDY WAS DESIGNED TO COMPARE THE EFFECTS OF FULL-FAT AND FAT-FREE DAIRY, WITH AND WITHOUT FERMENTATION (YOGURT), ON HEART DISEASE RISK FACTORS AND DETERMINE IF THE EFFECTS OBSERVED ARE MEDIATED BY THE BACTERIA IN OUR INTESTINE (GUT MICROBIOME) AND THE COMPONENTS THEY PRODUCE. TO ACCOMPLISH THIS WE WILL CONDUCT A RANDOMIZED-CONTROLLED CROSS-OVER TRIAL COMPARING THE EFFECT OF CONSUMING TWO SERVINGS/DAY OF FULL-FAT MILK, FAT-FREE MILK, FULL-FAT YOGURT AND FAT-FREE YOGURT ON HEART DISEASE RISK FACTORS (E.G., BLOOD LIPID AND GLUCOSE CONCENTRATIONS) AND THE GUT MICROBIOME COMPOSITION AND ITS PRODUCTS. HEART DISEASE AND RELATED DISORDERS ARE THE LEADING CAUSE OF DEATH AND DISABILITY IN THE U.S. POOR DIET QUALITY IS A MAJOR CONTRIBUTOR. IT IS MORE CRITICAL THAT EVER TO HAVE THE EVIDENCE BASE ON WHICH TO FORMULATION THE BEST ADVISE.