5. any current significant systemic illness or unstable medical condition that could lead to difficulty in complying with the protocol (such as unstable cardiovascular disease); current use of supplemental oxygen or hypoxemia indicated by documented daytime oxyhemoglobin saturation <90% on room air, uncontrolled thyroid disease (to be included must be on stable dose of thyroid medication for >6 months), uncontrolled cirrhosis, cancer diagnosis within the past 6 months, clinically significant laboratory abnormalities such as reported untreated folate, B12, or TSH disease, or resident of a skilled nursing facility;