By Greg Arnold, DC, CSCS, August 31, 2013, abstracted from “L-arginine enriched biscuits improve endothelial function and glucose metabolism: a pilot study in healthy subjects and a cross-over study in subjects with impaired glucose tolerance and metabolic syndrome” in the February 2013 issue of Metabolism
Metabolic Syndrome affects over 47 million Americans. It is characterized by a number of risk factors that include central obesity (excessive fat tissue in and around the abdomen), increased blood pressure (130/85 mmHg or higher), and insulin resistance (the body can’t properly use insulin to control blood sugar) (1). With the average yearly pharmacy cost for a patient with Metabolic Syndrome at $4,000, it has been called “the most expensive disease you’ve never heard of” (2).
While following a Mediterranean Diet (3) and consuming plant antioxidants called phytosterols (4) may help blood vessel health in those with Metabolic Syndrome, a new study (5) suggests the amino acid arginine may also be a benefit.
In the study, the researcher set up two different protocols with two different sets of patients. In the first protocol, seven healthy subjects with no signs of Metabolic Syndrome consumed biscuits enriched with 6.6 grams of L-arginine and containing 21.9 grams of carbohydrates, 3.6 grams of protein, 7.5 grams of fat and 4.3 grams of dietary fiber or placebo biscuitsand 6.6 grams of powdered L-arginine while following a 2,000 calorie diet consisting of foods approved in previous research (6).
In the second protocol, 15 obese subjects diagnosed with Metabolic Syndrome consumed the L-arginine-enriched biscuits from the first protocol or placebo biscuits in a 1,600 calorie per day diet eating foods approved in the previous research. Each protocol period lasted two weeks followed by a two-week washout period, after which the subjects switched protocols for two more weeks. Before the study began, after the first protocol, and after the second protocol, the subjects consumed an L-arginine-enriched biscuit and had their blood drawn periodically.
The researchers measured the effect of L-arginine supplementation on the elasticity of arteries. The forearm blood flow is essentially a measure of the elasticity of arteries, which tends to decrease due to plaque formation and the aging process. It was measured by inflating a blood pressure cuff on the upper arm to 100mmHg above the systolic blood pressure for 5 minutes and then releasing it. These measurements were performed at the beginning, and every 60 minutes until the end of the study.
The study was divided between healthy and obese subjects, each of whom consumed L-arginine biscuits. It was expected that healthy adults would have more elastic arteries and therefore greater blood flow compared to obese subjects. In addition, the researchers believed that L-arginine will improve the blood flow in both healthy and obese subjects.
The results showed that in healthy subjects the intake of L-arginine improved artery elasticity by 8%, (p<0.01). In the obese subjects the blood flow was improved by 17.1% after 2 hours (p<0.01) which is significant for protection from cardiovascular disease.
Basal forearm blood flow (mL/100mL/min)
Post-ischemic forearm blood flow (mL/100mL/min) (after 120 min)
While no blood sugar or insulin level differences were seen between groups in the first protocol of healthy subjects, those consuming biscuits in the second protocol of obese subjects had 13.3% lower blood sugar levels within 30 minutes of biscuit consumption (150 vs. 173 mg/dL, p < 0.05) and 10.5% lower insulin levels within 60 minutes of biscuit consumption (43 vs. 48 microunits/mL, p < 0.05). This improved blood sugar and insulin function produced a 5.6-pound weight loss in the biscuit group compared to 3 pounds of weight loss in the placebo group (p < 0.05), with 79.3% of the weight loss in the biscuit group coming from fat (4.44 pounds of fat lost) compared to 49% of weight loss from fat in the placebo group (1.54 pounds of fat lost) (p < 0.01).
For the researchers, “L-Arginine-enriched biscuits with low sugar and protein content enhance [blood vessel] function and improve [blood sugar control], insulin sensitivity and insulin secretion in subjects with Metabolic Syndrome.”
Greg Arnold is a Chiropractic Physician practicing in Hauppauge, NY. You can contact Dr. Arnold directly by emailing him at PitchingDoc@msn.com or visiting his web site at www.PitchingDoc.com
1. “Metabolic Syndrome” posted on the American Heart Association website
2. “Metabolic Syndrome: The Most Expensive Disease You’ve Never Heard Of” – Medical News Today, May 9, 2005
3. Rumawas M. Mediterranean-style dietary pattern, reduced risk of metabolic syndrome traits, and incidence in the Framingham Offspring Cohort. Am J Clin Nutr 2009;90 1608-1614
4. Phytosterols supplementation decreases plasma small and dense LDL levels in metabolic syndrome patients on a westernized type diet. Nutr Metab Cardiovasc Dis 2010, doi:10.1016/j.numecd.2010.12.004
5. Monti LD. L-arginine enriched biscuits improve endothelial function and glucose metabolism: a pilot study in healthy subjects and a cross-over study in subjects with impaired glucose tolerance and metabolic syndrome. Metabolism 2013 Feb;62(2):255-64. doi: 10.1016/j.metabol.2012.08.004
6. Societa` Italiana di Nutrizione Umana. LARN: Livelli di Assunzione Giornalieri Raccomandati di Energia e Nutrienti per la Popolazione Italiana. Revisione 1996. EDRA srl Ed,Milano 1998.