A French study published in the Nutrition
Journal suggests that the lower threshold intake (LTI) for protein must be set
at 1.2g per kg per day during the treatment based on physical activity and
restricted diet in older patients with metabolic syndrome.
Metabolic syndrome is defined by The International
Diabetes Federation (IDF) as 'the co-occurrence of any three of the five
following abnormalities: abdominal obesity (waist circumference greater than 94
cm in men and greater than 80 in women), LDL cholesterol levels of more than
1.5 mmol/l, HDL cholesterol less than 0.4 g/l in men and less than 0.5 g/l in
women, blood pressure greater than 130/85 and/or medical treatment, and fasting
glycemia more than 5.55 mmol/l and/or medical treatment'. Metabolic syndrome
increases the risk for type-2 diabetes, stroke and coronary artery disease.
The most efficient way to counteract metabolic
syndrome is to reduce overweight which is primarily achieved by reducing
calorie intake and increasing physical activity. But the challenge is in
reducing fat mass without affecting lean body mass, especially in older
patients since progressive loss of muscle mass is a natural phenomenon.
The study researchers, Frédéric Dutheil, at
Occupational Medicine, Faculty of Medicine, Clermont-Ferrand, France, and his
colleagues, suggest increasing protein intake optimally to maintain protein
homeostasis. As is known, physical activity increases the need for proteins.
This is because calorie restricted diets result in insufficient energy
production and proteins are needed to compensate for the energy deficit. The
body will use the proteins stored in the skeletal muscles for its energy
requirement, leading to an undesirable reduction of muscle mass.
Again, excessive protein intake will over-exert the
kidney and increase the urea and uric acid production and also increase the
intake of undesirable saturated fatty acids via proteins of animal origin.
So, in order
to preserve the muscle mass without over-exerting the kidney, it is necessary
to recommend neither too much nor too little protein for senior patients.
dietary allowance (RDA) for protein intake is 0.8g/kg/day for general
population and 1.0 to 1.3g/kg/day for older people. However, no consensus
exists on the lower threshold intake (LTI = RDA/1.3) for the protein intake
(PI) needed in senior patients undergoing exercise plus diet restriction
treatment for metabolic syndrome.
So, to quantify optimal PI requirement for seniors,
the researchers selected 28 metabolic syndrome patients aged between 50 to 70
years being treated with this combination therapy. The study involved a 3-week
residential program (Day 0 to Day 21) controlled for nutrition (negative energy
balance of 500 kcal/day) and physical activity of 3.5 hours per day and then a
follow-up of 6 months in the subject's own home.
Patients were divided into two groups - Normal-PI (1.0
g/kg/day) and High-PI (1.2 g/kg/day). The lower threshold intake for protein
was determined based on the normal presence of albumin in the blood
(albuminemia) which is the marker for protein homeostasis.
Results showed that albuminemia was 40.6 g/l for
Normal Protein Intake (NPI) group and 40.8 g/l for high protein intake (HPI)
group. At day 90, albuminemia decreased to 34.3 g/l for the NPI group
indicating marginal protein under-nutrition, but it was stable in the HPI
"Our study shows that LTI (and not RDA) for protein
must be set at 1.2 g/kg/d when physical activity together with reduced caloric
intake are prescribed to patients suffering from metabolic syndrome", says lead
researcher Frédéric Dutheil.
The researchers, however, agree that this amount of
protein intake could appear to be high for patients consuming light meals. They
calculated that for an 80-kg weighing patient this would mean 100g per day of
protein dry weight or 500g crude protein. If 50 percent of the protein intake
is from animal origin, then it would amount to 250g of meat or fish per day.
Eggs and cheese are avoided because of their high fat content. Again, 100g
protein represents 400 kcal, so if the total caloric intake is 2000 kcal,
proteins will form 20 percent of the diet.
The study was funded by the Heart and Diseases
Foundation (Fondation Coeur et Artères), France.
Dutheil F, et. al. Treatment of Metabolic
syndrome by combination of physical activity and diet needs an optimal protein
intake: a randomized controlled trial. Nutrition Journal 2012.