The aim of the present study is to validate a new method in healthy volunteers and those diagnosed with COPD and CHF that is able to measure protein digestion and absorption simultaneously. This method is used to quantify digestion and absorption in patients who are suspect of impaired digestion and absorption resulting in loss of nutrients.Findings may be used to develop treatment strategies to improve protein digestion and absorption in these patient groups.

The study involves 1 screening visit of approximately 1-2 hours and 1 test day of approximately 8 hours. On the study day protein digestion and absorption will be measured using a mixture of amino acids that are made slightly heavier than normal, called stable isotopes. Subjects will receive feeding by sips to monitor changes in digestion and absorption, which can be picked up by stable isotope technology.

IInclusion and exclusion criteria for study participation:

We will enroll subjects (males and females of all races) based on the inclusion/exclusion criteria described below. All subjects should be able to walk, sit and stand up indepedently. Screening procedures will be done prior to the study.

Inclusion criteria - CHF subjects:

• Ability to walk, sit down and stand up independently
• Age 45 years or older
• Ability to lie in supine or elevated position for 9 hours
• Diagnosis of CHF; under regular care by cardiologist
• Reduced ejection fraction (<45%) assessed in the past 2 years
• NYHA class II-IV
• Clinically stable condition; no hospitalization 4 weeks preceding first study day
• Willingness and ability to comply with the protocol

Inclusion criteria - COPD subjects:

• Ability to walk, sit down and stand up independently
• Age 45 years or older
• Ability to lie in supine or elevated position for 8 hours
• Diagnosis of moderate to very severe chronic airflow limitation and compliant to the following criteria: FEV1 < 70% of reference FEV1
• Clinically stable condition and not suffering from a respiratory tract infection or exacerbation of their disease (defined as a combination of increased cough, sputum purulence, shortness of breath, systemic symptoms such as fever, and a decrease in FEV1 > 10% compared with values when clinically stable in the preceding year) at least 4 weeks prior to the first test day
• Shortness of breath on exertion
• Willingness and ability to comply with the protocol

Inclusion criteria - healthy subjects:

• Healthy male & female according to the investigator's or appointed staff's judgment
• Age 45 years and older, or 20 - 30 for healthy young group

Exclusion Criteria - all subjects:

• Any condition that may interfere with the definition 'healthy subject' according to the investigator's judgment (healthy subjects only)
• Established diagnosis of malignancy
• History of untreated metabolic diseases including hepatic or renal disorder
• Presence of acute illness or metabolically unstable chronic illness
• Presence of fever within the last 3 days
• Body mass index >40 kg/m2 (healthy subjects only)
• Any other condition according to the PI or nurse that was found during the screening visit, that would interfere with the study or safety of the patient
• Use of protein or amino acid containing nutritional supplements within 5 days prior first study day
• Current Use of long-term oral corticosteroids (CHF only)
• Use of short course of oral corticosteroids within 4 weeks preceding first study day
• Failure to give informed consent or Investigator's uncertainty about the willingness or ability of the subject to comply with the protocol requirements
• (Possible) pregnancy
• Already enrolled in another clinical trial and that clinical trial interferes with participating in this study