Plant-based diets are naturally low in Methionine (Met), and also low in precursor molecules (e.g L-carnitine, choline, betaine, etc.) producing microbiota-mediated proatherogenic TMAO. Among plant proteins, pulses are rich in micronutrients, and dietary fibers, making them ideal for microbiome-stimulating, nutrient-dense, healthful dietary patterns. However, daily pulse intake remains low at 8% in America despite recommendations by DGA, a resource to guide health promotion across communities. A significant body of preclinical data, waiting to be translated to humans, suggests that dietary Met restriction can trigger beneficial metabolic and anti-inflammatory adaptations leading to improved chronic health and longevity. The central hypothesis is that a pulse-protein-based healthy diet can be simultaneously equivalent to omnivorous diets in protein content and yet naturally lower in Met and TMAO to improve glycemic control, body composition, and immunometabolic flexibility to reduce the risk of chronic diseases and improve healthspan. The goal is to systematically elucidate for the first time the effects of a lacto-vegetarian feeding pattern with pulses as the primary protein source on a comprehensive panel of ~500 traditional and next-generation biomarkers of health, and assess the role of the gut microbiota in mediating such effects. We also aim to interrogate the potential concern about the lower bioavailability of non-heme iron from pulses.

Inclusion Criteria:

• Generally good health status based on routine physical in the past 12 months, current healthy status
• Normal HbA1C, not underweight
• Age 60 years or more, all races, both sexes and all education level
• Do not have any special dietary requirements and willing to consume vegetarian diet
• Willingness to comply with the study protocol, including on-site meal consumption and sample/data collection.

Exclusion Criteria:

• Probiotic, long-term antibiotic, and tobacco/drug/alcohol use
• Not on any special diet within 3 months of recruitment
• Impaired kidney functions
• Active history of cancer, diabetes, heart, liver, and kidney diseases
• Major gastrointestinal disorders in the past 3 months
• History of heart attacks or stroke
• Unable to meet in-person visit requirements for dining, picking up meals, and tests
• Any mental health condition that would affect the ability to provide written informed consent.
• If they had not had a routine health checkup during the 12 months prior to recruitment.
• If they were unwilling to abstain from taking certain nutritional supplements, alcohol, or non-study foods during the study period.

Blinding will be implemented to the extent possible. A researcher, unaware of the study goals and not involved with downstream data analyses will use a 1:1 block randomization to allocate participants to the diets in the first arm. Food service personnel (care provider) will not be aware of study goals and allocations. Metabolomic assays will be run in a blinded manner.