When do you need arginine?

Arginine is used for synthesis of protein, agmatine, polyamines and creatine [1]. Because kidneys synthesize arginine usually in sufficient amounts in the urea cycle(releasing 2-4g daily), it's normally not necessary to attain it from the diet [1p196;229].

At times, however, arginine can become conditionally essential [1p229]. Such times would include protein malnutrition, excessive ammonia production, excessive lysine intake, burns, infections, peritoneal dialysis, rapid growth, urea synthesis disorders, or in the inflammatory state of sepsis [2]. A deficiency could result in fatty liver, poor wound healing, hair loss, skin rash and constipation [2].

Arginine is changed into nitric oxide causing blood vessel relaxation [2], which can lower blood pressure. Thus, should not be used by a patient with low blood pressure [3]. If suffering of sickle cell disease, arginine can worsen symptoms [3].

One should exercise caution if supplementing with arginine because the amino acid is known to result in anaphylaxis in patients with certain allergies [3]. Those on anticoagulants should note that arginine can increase risk of bleeding [3]. It can increase potassium levels, especially in liver disease patients [3]. And the amino acid can increase blood sugar levels so may be contraindicated for patients who are trying to control blood sugar levels [3].

Reference List
1. Gropper SS, Smith JL, Groff JL. Advanced Nutrition and Human Metabolism. Belmont, CA: Thomson Wadsworth, 2009.
2. Mayo Clinic. "Arginine (L-arginine): Background." Available at: http://www.mayoclinic.com/health/l-arginine/NS_patient-arginine.
3. Mayo Clinic. "Arginine (L-arginine): Safety." Available at: http://www.mayoclinic.com/health/l-arginine/NS_patient-arginine/DSECTION=safety.

Hypoparathyroidism

Hypoparathyroidism is not as common as hyperparathyroidism and is characterized by secretion of low levels of parathyroid hormone (1). The disorder can be result of removal of parathyroid glands, the glands’ possible autoimmune destruction, or, in some genetic cases, when the kidney is insensitive to parathyroid output (1).

When low parathyroid hormone occurs, hypocalcemia and hyperphosphatemia can become end results. Symptoms include weakness, mental process alterations and faulty muscular function (1).

Patients with hypoparathyroidism are advised to make dietary changes to increase calcium and avoid phosphorus such as found in many soft drinks (2). Treatment for hypoparathyroidism include dietary supplementation with calcium and vitamin D, which helps the body absorb calcium and get rid of phosphorus (2).

Reference List

1. Nowak TJ, Handford AG. Pathophysiology: Concepts and Applications for Health Professionals. New York: McGraw-Hill, 2004.
2. Mayo Clinic. Hypoparathyroidism. Available at: http://www.mayoclinic.com/health/hypoparathyroidism/DS00952/DSECTION=treatments-and-drugs.

How is urea regulated?

Urea cycle regulation is dependent on dietary factors and hormone concentrations (1). A feed-forward regulation exists in that available ammonia causes more urea to be created (1). This can also mean that higher protein can also act as a feed-forward regulation since it increases urea enzyme levels (1-2). Ammonia can come from diet, from deamination, or bacteria in the GI tract inducing formation of carbamoyl phosphate by mitochondrial carbamoyl phosphate synthetase (1).

Other regulation also exists. First, synthesis of n-acetyl glutamate, which is the allosteric activator of the carbamoyl phosphate synthetase (2). The activator is made in the liver and intestine when stimulated by available arginine (1-2). Second, arginase is inhibited by ornithine and lysine making it able to become rate limiting (1).

Reference List
1. Gropper SS, Smith JL, Groff JL. Advanced Nutrition and Human Metabolism. Belmont, CA: Thomson Wadsworth, 2009.
2. Lieberman M, Marks A, Smith CM, Marks DB. Marks’ basic medical chemistry, ed 3. Lippincott Williams & Wilkins, 2008.

“Goods” and “bads” of extra protein in sports

While Dietary Reference Intakes for protein are 0.8g protein per kg for adults, data suggest athletes may need more depending on their sport, particularly strength-training athletes (1). Research also indicates that even non-athletes who weight train may benefit from the added protein (2). Endurance exercise sports such as cycling and running increase protein turnover, including a lot more oxidation amino acids, so it is suggested that extra protein would also be wise (3;4).

However, many athletes often exceed intake required (5). While the positive balance may not affect competitiveness, excessiveness does not encourage further muscle growth or strength gain (5). It should also be noted that strength-training itself also encourages improved utilization of dietary protein possibly reducing need of added protein (5). When consumed with carbohydrate, net protein balance during and after endurance exercise is improved, but there is little evidence of actual improved performance due to the extra protein (3). There is also little evidence that the extra protein will stimulate muscle growth or strength (6).

Because daily requirements for protein are set by amount of protein lost, any extra protein should be added to make up for the loss and to maintain nitrogen balance (5). Protein intake that is excessive can lead to potential complications such as in the kidneys (if disease is onset) (7-10) and possible bone fracture if acidosis occurs (11).

Reference List

1. Phillips SM. Dietary protein for athletes: from requirements to metabolic advantage. Appl Physiol Nutr Metab 2006;31:647-54.
2. Evans WJ. Protein nutrition, exercise and aging. J Am Coll Nutr 2004;23:601S-9S.
3. Gibala MJ. Protein metabolism and endurance exercise. Sports Med 2007;37:337-40.
4. Tarnopolsky M. Protein requirements for endurance athletes. Nutrition 2004;20:662-8.
5. Phillips SM. Protein requirements and supplementation in strength sports. Nutrition 2004;20:689-95.
6. Dohm GL. Protein nutrition for the athlete. Clin Sports Med 1984;3:595-604.
7. Pecoits-Filho R. Dietary protein intake and kidney disease in Western diet. Contrib Nephrol 2007;155:102-12.
8. Manninen AH. High-protein diets are not hazardous for the healthy kidneys. Nephrol Dial Transplant 2005;20:657-8.
9. Friedman AN. High-protein diets: potential effects on the kidney in renal health and disease. Am J Kidney Dis 2004;44:950-62.
10. Donini LM, Pinto A, Cannella C. [High-protein diets and obesity]. Ann Ital Med Int 2004;19:36-42.
11. Mardon J, Habauzit V, Trzeciakiewicz A et al. Long-term intake of a high-protein diet with or without potassium citrate modulates acid-base metabolism, but not bone status, in male rats. J Nutr 2008;138:718-24.

Spoonful of any kind of sugar makes the protein go down after exercise

It's clear that carbohydrates with protein affects insulin, thereby inducing glycogen synthesis. However, I was left thinking, “But what kind of carbohydrate is best?” And I found a study that suited my curiosity. One published in 2007 in J Int Soc Sports Nutr showed that 40 subjects who weight trained taking 40g of whey protein were also given 120g of sucrose, honey or maltodextrin (1). After 30 minutes, the honey group showed greatest glucose concentration and best degree of blood glucose maintenance; however, there was really no significant difference and either can be used (1).

Reference List
1. Tipton KD, Elliott TA, Cree MG, Aarsland AA, Sanford AP, Wolfe RR. Stimulation of net muscle protein synthesis by whey protein ingestion before and after exercise. Am J Physiol Endocrinol Metab 2007;292:E71-E76.

Can arginine make you look like Arnold?

Arginine is a precursor for nitric oxide, which relaxes vascular smooth muscle leading to improved blood flow and, thus, the flow of nutrients to muscles (1;2). Oral arginine appears to also stimulate growth hormone release, especially when taken with exercise (3). Supplementation with arginine didn’t increase body mass significantly in a study in 2008; although, when taken with creatine, arginine did improve endurance and power of muscle (2).

Reference List
1. Gropper SS, Smith JL, Groff JL. Advanced Nutrition and Human Metabolism. Belmont, CA: Thomson Wadsworth, 2009.
2. Little JP, Forbes SC, Candow DG, Cornish SM, Chilibeck PD. Creatine, arginine alpha-ketoglutarate, amino acids, and medium-chain triglycerides and endurance and performance. Int J Sport Nutr Exerc Metab 2008;18:493-508.
3. Kanaley JA. Growth hormone, arginine and exercise. Curr Opin Clin Nutr Metab Care 2008;11:50-4.

Will glutamine give you big guns?

You might think so.

In theory, glutamine supplementation appears to make sense. Supplementation increases plasma glutamine in the plasma (1), which is thought to support the immune system (2;3) because the immune system uses glutamine for energy production (4). Plus, because exercise causes muscles to increase use of glutamine, stores are depleted (4). However, according to a 2001 study showed glutamine does not have any “significant effect on muscle performance, body composition or muscle protein degradation” (5).

Reference List
1. Maughan RJ. Nutritional ergogenic aids and exercise performance. Nutr Res Rev 1999;12:255-80.
2. Williams MH. Facts and fallacies of purported ergogenic amino acid supplements. Clin Sports Med 1999;18:633-49.
3. Nieman DC. Exercise and resistance to infection. Can J Physiol Pharmacol 1998;76:573-80.
4. Gropper SS, Smith JL, Groff JL. Advanced Nutrition and Human Metabolism. Belmont, CA: Thomson Wadsworth, 2009.
5. Candow DG, Chilibeck PD, Burke DG, Davison KS, Smith-Palmer T. Effect of glutamine supplementation combined with resistance training in young adults. Eur J Appl Physiol 2001;86:142-9.