Effects of Amino Acids on Regional Lipid Metabolism
Condition: Hypertriglyceridemia
MeSH terms: Hypertriglyceridemia
Study type: Interventional

Summary: 
      Elevated fat level in blood is a risk factor for coronary heart disease, a major cause of
      death in America. The overall goal of this project is to test a novel treatment using
      nutrient (amino acid) supplementation against this condition in men and women, and to
      understand how this treatment works.
    

Detailed description: 
      Coronary heart disease (CHD) remains the single largest killer of American men and women
      (45). Hyper¬triglyceridemia (elevated triglyceride [TG] concentration in the blood) has been
      shown to be a significant independent risk factor for CHD (7;8;25), accordingly, treatment
      for hypertriglyceridemia has been included in the Adult Treatment Panel III (ATP III) of the
      National Cholesterol Education Program (36). In a meta-analysis of 21 population-based
      prospective studies including a total of 65,863 men and 11,089 women, each increase of 89
      mg/dl (1 mmol/l) in TG concentration was associated with a 32% increase in CHD risk in men
      and 76% increase in women (3). Thus, hypertriglyceridemia is an even stronger risk factor for
      CHD in women than in men.

      The prevalence of hypertriglyceridemia is high. It is a common finding with aging, and is
      also associated with overweight, obesity, diabetes, and renal disease (39). With the aging of
      the US population and ongoing epidemics of obesity and type 2-diabetes, the number of
      individuals with conditions associated with elevated TG levels is likely to grow.

      4.1.2 Effect of Amino Acids on Plasma Triglyceride Concentration In an effort to clarify the
      potential independent effect of protein on plasma and tissue lipids, we supplemented a normal
      weight-maintaining diet with a relatively small amount of amino acids (~90 kcal/day) between
      meals. We measured tissue lipids in addition to plasma lipids since the increase in insulin
      resistance with aging has been linked to increased fat accumulation in muscle and liver
      tissue (20;63). Also, it has repeatedly been shown that amino acid intake stimulates muscle
      protein synthesis and improves muscle protein net balance (86). Our hypothesis was that
      supplementation of the normal diet with a mixture of amino acids will reduce circulating and
      tissue TG concentrations and improve insulin sensitivity in elderly subjects with impaired
      glucose tolerance. Twelve impaired glucose tolerant elderly ingested 11 g of essential amino
      acids (EAA) + arginine twice a day for 16 weeks, after a 7 week control run in. Diet and
      activity were not otherwise modified. We found individuals consuming the EAA supplement had
      improved physical function. Further, these individuals had lower plasma and liver TG
      concentrations than before supplementation, and total cholesterol and VLDL-cholesterol
      concentrations were also lower after supplementations (12). In the present study, we will
      investigate this by supplementing the diet of older subjects shown to have
      hypertriglyceridemia.
    

Intervention name(s): Amino acids; Placebo
Intervention type(s): Dietary Supplement; Dietary Supplement
Intervention description(s): 11 g amino acids two times per day for eight weeks; Placebo of inert compounds, 11 g two times per day for eight weeks
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double (Participant, Investigator)
Primary purpose: Basic Science
Keywords: aging; lipid metabolism; very low density lipoproteins; amino acids; dietary supplements