Protein Arginine Reduces Obesity and Insulin Resistance

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Copyright © 2011, Harvard University. For more information about The Healthy Eating Plate, please see The Nutrition Source, Department of Nutrition, Harvard School of Public Health, www.thenutritionsource.org, and Harvard Health Publications, health.harvard.edu

The Harvard Healthy Eating Plate emphasizes plant-based foods. Image courtesy of Harvard College

Soaring rates of obesity and diabetes have resulted in a sea-change in diet recommendations. The American food pyramid now includes a greater role for plant-based foods, and there has been a call for the United Kingdom to convert to a plant-based diet.

Is a plant-based diet adequate for our nutritional needs? Meat-eaters may be surprised to learn that the plant-based diet is abundant in L-arginine, a protein that reduces obesity and insulin resistance.

Radical Changes in Diet Proposed

Recently, the World Preservation Foundation proposed that the UK convert to a plant-based diet. Gerard Wedderburn-Bishop, Executive Director of the World Preservation Foundation told Decoded Science:

“Non-communicable diseases (cardiovascular diseases, cancers, chronic respiratory diseases and diabetes) are now the leading causes of death globally, responsible for 63% of all deaths worldwide.

The World Economic Forum and Harvard School of Public Health estimated that the economic impact of NCDs over the next two decades will be US$ 47 trillion, equivalent to 75% of 2010 global GDP[i].

We must take urgent action to stem this threat, which could bankrupt national health care systems. The good news is that plant-based diets are an effective, low cost, easily adopted means of tackling NCDs.”

Protein and the Plant-Based Diet: Amino Acids

Concern for protein is a major issue for meat-eaters. The body uses 10,000 different proteins to maintain health, and approximately 20 amino acids are needed to build these proteins. Essential amino acids are not stored by the body, however, and must be consumed as food. Are plant-based diets able to fill those needs? As early as 1999, DJ Milward, of the Centre for Nutrition and Food Safety,  University of Surrey, Guildford, UK, demonstrated that essential amino acids were, in fact, adequate in plant-based diets.

In more recent news, Dr. Guoyao Wu of Texas A&M, published a study on this subject in the November 2010 issue of Advances in Nutrition.

  • In this study, Wu asserts that functional, or non-essential, amino acids regulate key metabolic processes that are essential for growth and development.
  • Wu also contends that functional proteins labeled “non-essential” amino acids should be re-classified.
  • Dr. Wu identified glutamine and arginine as critical amino acids for survival, reproduction, lactation, growth and development. Glutamine provides immunity for the intestines, and particularly the small intestine, which absorbs huge amounts of this protein.   Studied in post-weaning pigs, glutamine protects the newborn from infection when food is introduced. Rich sources of glutamine are found in spinach, cabbage, parsley, oats and wheat germ. Dairy sources include milk, cottage cheese and ricotta cheese. Animal sources are eggs, pork and chicken.

Health Benefits of L-Arginine

L-Arginine is a plant-based protein that reduces obesity. Image by Photohound

Dr. Wu is particularly excited about the functional amino acid arginine, which has a profound impact on healthy early animal development.

Wu’s studies of arginine have demonstrated that the amino acid can prevent developmental delays and retardation.  Wu is convinced that arginine is critical in prenatal, newborn and early childhood development in humans. In addition, according to Wu, arginine has a huge role in a metabolic process that controls obesity.

  1. Arginine diverts nutrients to building muscles and bone, rather than to accumulation of fat.
  2. Wu’s research in pigs has shown that – without gaining weight – arginine reduces the volume of fat and increases lean muscle tissue.

The explosion in the incidence of type 2 diabetes is one of the most troubling aspects of the obesity epidemic. According to Dr. Wu, arginine acts in a manner that indirectly reduces insulin resistance. This is accomplished by arginine’s ability to reduce other amino-acid chains that have been shown to lead to insulin resistance. Beans, nuts and whole grains – the protein sources for the plant-based diet – are also the primary food sources for the amino acid arginine.

Dr. Wu proposes that human studies begin as soon as possible in the area of functional amino acids, and the use of arginine to prevent obesity, diabetes, and metabolic syndrome in humans.

New Hope for Prevention of Obesity: The Plant-based Diet and Arginine

Studies have demonstrated that a plant-based diet can provide sufficient supplies of critical proteins.  Even as concern for protein prevents many from embracing a vegetarian diet, studies are underway that investigate the possibility that the protein arginine, abundant in the plant-based diet, may be a solution for the world-wide problem of obesity and chronic disease.

References:

Bloom, D.E., Cafiero, E.T., Jané-Llopis, E., Abrahams-Gessel, S., Bloom, L.R., Fathima, S., Feigl, A.B., Gaziano, T., Mowafi, M., Pandya, A., Prettner, K., Rosenberg, L., Seligman, B., Stein, A., & Weinstein, C. (2011). The Global Economic Burden of Non-communicable Diseases. Geneva: World Economic Forum. Accessed November 25, 2011.

Millward, DJ. The Nutritional Value of Plant-Based Diets in Relation to Human Amino Acid and Protein Requirements. Centre for Nutrition and Food Safety. (1999). Accessed November 25, 2011.

Jobgen, W. , Meininger, C., Jobgen, S., Li, P., Lee, M., Smith, S., Spencer, T., Fried, S., Wu, G. Dietary L-Arginine Supplementation Reduces White Fat Gain and Enhances Skeletal Muscle and Brown Fat Masses in Diet-Induced Obese Rats. Journal of Nutrition 139(2): 230-237. (2009). Accessed November 25, 2011.

World Preservation Foundation. Plant-based lifestyle could save the NHS billions of pounds. (September 2011). Accessed November 25, 2011.

Harvard School of Public Health. Protein: Moving Closer to Center Stage. (Nov. 4, 2011). Accessed 25 November, 2011.

TRIENNIAL GROWTH SYMPOSIUM: Important roles for L-glutamine in swine nutrition and production. J ANIM SCI. (July 1, 2011). 89 7): 2017-2030.

Wu G., “Functional Amino Acids in Growth, Reproduction, and Health,” Advances in Nutrition. (2010). Accessed November 25, 2011.

For more information about The Healthy Eating Plate, please see The Nutrition Source, Department of Nutrition, Harvard School of Public Health.

Disclaimer: The information contained in this article is for educational purposes only and should not be used for diagnosis or to guide treatment without the opinion of a health professional. Any reader who is concerned about his or her health should contact a doctor for advice.

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