The aim of this study is to evaluate the effects of a supplementation of citrulline for three weeks in elderly malnourished and hospitalised subjects on muscle protein synthesis.

Malnutrition in the elderly causes an important public health problem because their response to re nutrition is highly decreased. Several experimental studies have shown that an amino acid named citrulline could avoid this, by restoring protein synthesis.

The treated group will receive each morning for three weeks a supplementation of 10 g of citrulline and the control group, non essential amino acids in iso-nitrogenous quantity to the 10g of citrulline.

During the three weeks of supplementation, clinical tolerance and physical exercise will be evaluated regularly.

On the 21st day, whole body protein synthesis rate in the post-absorptive state will be measured by the isotopic dilution of L-leucine (1-13C expressed in g / kg of lean mass / 24h) as well as other parameters of the protein turn-over in the post-absorptive and post-prandial state.

Inclusion Criteria:

• elderly hospitalised in geriatric medicine or in following care and rehabilitation, moderately malnourished
• aged more than 70 years
• recent moderate undernutrition (30 g/l < albuminemia < 35 g/l and 18 < BMI < 22 or a score of the Mini Nutritional Assessment (MNA) < 17 with albuminemia > 30 g/l)
• ingesta of at least 20 kcal / kg / d and 0,8 g / kg / d of proteins

Exclusion Criteria:

• hospitalisation < 21d
• C reactive protein (CRP) > 50 mg / l
• end-stage cardiac insufficiency
• severe digestive incapacity
• renal insufficiency (Creatinine Clearance < 30 ml / mn)
• respiratory failure
• MMS < 18
• uncontrolled acute or chronic infectious pathology (HIV, tuberculosis)
• corticoids treatment
• evolutionary neoplasia
• palliative phase of severe pathology
• Mental Mini Score status of Folstein (MMS) < 8
• parenteral nutrition
• active chronic hepatitis or cirrhosis
• participation in another trial