Studies in laboratory models indicate that dietary methionine restriction (MR) enhances longevity and produces short- and long-term metabolic changes that are consistent with a healthy lifespan. The present study was designed to establish levels of dietary methionine or methionine and cysteine that induce physiological changes in healthy adults like those observed in rodent studies .

In this controlled feeding study, subjects will be randomized to one of two experimental. Group A (N=10): will start with control diet (31 mg/kg/day Met; 31 mg/kg/day Cys) for 4 weeks followed by a washout for 3-4 weeks, then a 70% MR diet (9.3 mg/kg/day Met; 40.3 mg/kg/day SAA) for 4 weeks, followed by 3-4 weeks washout period and then a 90% MR diet (3.1 mg/kg/day Met; 34.1 mg/kg/day SAA) for 4 weeks. Group B (N=10): will start with control diet (31 mg/kg/day Met; 31 mg/kg/day Cys) for 4 weeks followed by a washout for 3-4 weeks then a 50% methionine and cysteine restricted (M/CR) diet (15.5 mg/kg/day Met; 15.5 mg/kg/day Cys; 31 mg/kg/day SAA), followed by 3-4 weeks washout period and then a 65% M/CR diet (10.8 mg/kg/day Met; 10.8 mg/kg/day Cys; 21.6 mg/kg/day SAA) for 4 weeks.

Inclusion Criteria:

• Healthy English speaking male and female volunteers
• May or may not be students
• Age range 24-65 years
• Subjects will need to be of normal weight or moderately overweight (BMI 18.5-35 kg/m2)
• Subjects will be non-smokers

Exclusion Criteria:

• No use of medications known to impact the biomarkers of interest
• Pregnancy and lactating women
• Persons with documented diabetes
• No use of high dose dietary antioxidant supplements or fish oil/flax seed oil for n-acetylcysteine for at least 1 month prior to the study
• Use of tobacco products over the past 6 months
• Unstable weight
• Individuals with allergies to eggs, wheat, nuts, soy and latex
• Individuals with phenylketonuria (PKU)