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Now® L-Citrulline

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Description
Cardiovascular Health
  • 100% Pure Powder
  • Promotes Nitric Oxide Production
  • Supports Vascular Blood Flow*



L-Citrulline is a non-essential amino acid that is an important intermediate in the urea cycle, functioning along with Arginine and Ornithine to rid the body of ammonia, a byproduct of protein metabolism. Because Citrulline is a precursor of Arginine, it provides a readily available source material for Arginine production, which in turn, can be used for the production of Nitric Oxide (NO). NO plays a fundamental role in vascular function and blood flow. Citrulline therefore, not only supports detoxification pathways, but also supports NO production and a healthy cardiovascular system.*

* These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

Supplement Facts

As a dietary supplement, take one or two 1/4 level teaspoons 1 to 2 times daily between meals.

Serving Size 1.5 grams
Servings Per Container 75
Amount Per Serving % DV
L-Citrulline 1.50 g **
** Daily Value (DV) not established

Storage Instructions: Store in a cool dry place.

This product is sold by weight not volume.

Warning: Do not eat Freshness Packet Enclosed.

NOW FOODS, BLOOMINGDALE, IL 60108

Health Notes

L-Tryptophan

L-Tryptophan
This nutrient has been used in connection with the following health goals
  • Reliable and relatively consistent scientific data showing a substantial health benefit.
  • Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
  • For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support.

Our proprietary "Star-Rating" system was developed to help you easily understand the amount of scientific support behind each supplement in relation to a specific health condition. While there is no way to predict whether a vitamin, mineral, or herb will successfully treat or prevent associated health conditions, our unique ratings tell you how well these supplements are understood by the medical community, and whether studies have found them to be effective for other people.

For over a decade, our team has combed through thousands of research articles published in reputable journals. To help you make educated decisions, and to better understand controversial or confusing supplements, our medical experts have digested the science into these three easy-to-follow ratings. We hope this provides you with a helpful resource to make informed decisions towards your health and well-being.

This supplement has been used in connection with the following health conditions:

Pain
Dose: 2 to 4 grams per day
Double-blind research has also shown that oral L-tryptophan can increase tolerance to acute pain. (more)
Migraine Headache
Dose: Refer to label instructions
Preliminary research has found abnormally low levels of serotonin in the brains of people suffering a migraine attack, which was reversed with L-tryptophan supplements. (more)
Insomnia
Dose: 1 to 2 grams at bedtime
L-tryptophan has been used successfully for people with insomnia in many studies,including double-blind trials. (more)
Restless Legs Syndrome
Dose: 1 to 2 grams at bedtime
Preliminary research has shown some benefit reducing symptoms of restless legs syndrome and the insomnia that often accompanies it. (more)
Premenstrual Syndrome
Dose: 2 to 6 grams per day, during the second half of the menstrual cycle
Some research suggests that L-tryptophan may help balance mood symptoms associated with PMS. (more)
Bulimia
Dose: Refer to label instructions
L-tryptophan may be beneficial for people with bulimia, as this amino acid synthesizes serotonin, a hormone that helps regulate food intake and appetite.(more)
Bulimia
Dose: Refer to label instructions
Vitamin B6, when taken with L-tryptophan, has been shown to improve eating behavior, feelings about eating, and mood among women with bulimia.(more)
Premenstrual Syndrome
Dose: 2 to 6 grams per day, during the second half of the menstrual cycle
Some research suggests that L-tryptophan may help balance mood symptoms associated with PMS. (more)
Depression
Dose: 3 to 6 grams per day
Several controlled trials have found L-tryptophan as effective as antidepressant medications. Depressed people should consult a doctor before use. (more)
Seasonal Affective Disorder
Dose: With doctor's supervision, 2 to 4 grams per day, increasing up to 6 grams if no improvement
Some research suggests that L-tryptophan alone or in combination with light therapy may improve SAD symptoms. (more)
Anxiety
Dose: Refer to label instructions
Research suggests a connection between anxiety and serotonin deficiency and that its precursur L-tryptophan may help reduce anxiety in people with social anxiety disorder and neurosis. (more)
Hypertension
Dose: Refer to label instructions
The brain chemical serotonin may affect blood pressure regulation, and animal research suggests its precursur L-tryptophan may help prevent and manage hypertension. (more)
Obesity
Dose: Refer to label instructions
Animal research and preliminary human reports suggest that serotonin precursors such as L-tryptophan might help control appetite and promote weight loss. (more)
Attention Deficit-Hyperactivity Disorder
Dose: Refer to label instructions
Imbalances in the brain chemical serotonin, or low blood levels of its precursor, L-tryptophan, have been associated with ADHD in some (though not all) studies (more)
Bipolar Disorder
Dose: Refer to label instructions
Supplementation with L-tryptophan has led to improvement in depression in many studies, though its effect on bipolar disorder needs more study.(more)
Schizophrenia
Dose: 1 to 8 grams per day (under a doctor's supervision)
L-tryptophan supplementation has occasionally been helpful for specific schizophrenia symptoms, such as aggression and memory function. (more)
Anxiety
Dose: Refer to label instructions
Research suggests a connection between anxiety and serotonin deficiency and that its precursur L-tryptophan may help reduce anxiety in people with social anxiety disorder and neurosis. (more)
Pain
Dose: 2 to 4 grams per day Other amino acids may be beneficial in reducing pain. Animal research has shown that the brain chemical serotonin is involved in pain perception,1 and some,2, 3 though not all,4 preliminary human studies have reported reduced pain sensitivity when people took 2.0 to 2.75 grams per day of L-tryptophan, a precursor of serotonin. In a double-blind study, patients recovering from gallbladder surgery reported less pain when they were given L-tryptophan intravenously in the amount of 7.5 to 15 mg per 2.2 pounds body weight.5 Double-blind research has also shown that oral L-tryptophan can increase tolerance to acute pain when taken in amounts of at least 2 grams per day.6, 7 Two double-blind trials found that 3 to 4 grams per day of L-tryptophan along with a low-protein, high-carbohydrate diet reduced pain in people with chronic pain.8, 9 However, one controlled study did not find L-tryptophan (50 mg per 2.2 pounds of body weight per day) helpful for people with chronic pain around the temporomandibular joint.10 No research has been published investigating the pain control potential of 5-HTP (5-hydroxytryptophan), another serotonin precursor.
References

1. Haze JJ. Toward an understanding of the rationale for the use of dietary supplementation for chronic pain management: the serotonin model. Cranio 1991;9:339-43.

2. Leiberman HR, Corkin S, Spring RJ, et al. Mood, performance and pain sensitivity: changes induced by food constituents. J Psychiatr Res 1982;17:135-45.

3. Shpeen SE, Morse DR, Furst ML. The effect of tryptophan on post-operative endodontic pain. Oral Surg Oral Med Oral Pathol 1984;58: 446-9.

4. Ekblom A, Hansson P, Thomsson M. L-tryptophan supplementation does not affect postoperative pain intensity or consumption of analgesics. Pain 1991;44:249-54.

5. Ceccherelli F, Diani MM, Altafini L, et al. Postoperative pain treated by intravenous L-tryptophan: a double-blind study versus placebo in cholecystectomized patients. Pain 1991;47:163-72.

6. Seltzer S, Stoch R, Marcus R, Jackson E. Alteration of human pain thresholds by nutritional manipulation and L-tryptophan supplementation. Pain 1982;13:385-93.

7. Mitchell MJ, Daines GE, Thomas BL. Effect of L-tryptophan and phenylalanine on burning pain threshold. Phys Ther 1987;67:203-5.

8. Seltzer S, Dewart D, Pollack RL, Jackson E. The effects of dietary tryptophan on chronic maxillofacial pain and experimental pain tolerance. J Psychiatr Res 1982-1983;17:181-6.

9. Brady JP, Cheatle MD, Ball WA. A trial of L-tryptophan in chronic pain syndrome. Clin J Pain 1987;3:39-43.

10. Stockstill JW, McCall WD Jr, Gross AJ, Piniewski B. The effect of L-tryptophan supplementation and dietary instruction on chronic myofascial pain. J Am Dent Assoc 1989;118:457-60.

Migraine Headache
Dose: Refer to label instructions

Interest in the effects of serotonin on the mechanisms of migraine has led to therapeutic trials using serotonin precursors such as L-tryptophan and 5-hydroxytryptophan (5-HTP).1 Preliminary research has found abnormally low levels of serotonin in the brains of people suffering a migraine attack, which was reversed with L-tryptophan supplements.2 A small double-blind trial found that four of eight people had fewer and less intense migraines while receiving L-tryptophan (500 mg every six hours).3 Larger double-blind trials are needed to better evaluate L-tryptophan as a migraine prevention supplement.

In one study, 40 people with recurrent migraines received either 5-HTP (200 mg per day) or methysergide (a drug used to prevent migraines) for 40 days. Both compounds reduced the frequency of migraines by about 50%.4 Larger amounts of 5-HTP (600 mg per day) were also found to be as effective as medications for reducing migraine headache attacks in adults in two double-blind trials.5, 6 Migraine attacks were reduced in frequency, severity, and duration in 90% of those taking 400 mg per day of 5-HTP in a double-blind placebo-controlled trial,7 though another trial found no benefit of 5-HTP.8 In another controlled study, 400 mg per day of DL-5-HTP (another form of 5-HTP, equivalent to 200 mg per day of 5-HTP per day led to reduced consumption of pain-killing drugs and pain scores after one to two months.9 Children who suffered from migraines and had problems sleeping had an improvement in both migraines and sleep disorders after taking 5-HTP in the amount of 20 mg for every 10 pounds of body weight in a controlled trial,10 though an earlier study showed 5-HTP had no better effect than placebo for children with migraines.11

References

1. Kimball RW, Friedman AP, Vallejo E. Effect of serotonin in migraine patients. Neurology 1960;10:107-11.

2. Poloni M, Nappi G, Arrigo A, Savoldi F. Cerebrospinal fluid 5-hydroxyindoleacetic acid level in migrainous patients during spontaneous attacks, during headache-free periods and following treatment with L-tryptophan. Experientia 1974;30:640-1.

3. Kangasniemi P, Falck B, Langvik V-A, Hyyppa MT. Levotryptophan treatment in migraine. Headache 1978;18:161-6.

4. Sicuteri F. The ingestion of serotonin precursors (L-5-hydroxytryptophan and L-tryptophan) improves migraine headache. Headache 1973;13:19-22.

5. Titus F, Davalos A, Alom J, Codina A. 5-hydroxytryptophan versus methysergide in the prophylaxis of migraine. Eur Neurol 1986;25:327-9.

6. Maissen CP, Ludin HP. Comparison of the effect of 5-hydroxytryptophan and propranolol in the interval treatment of migraine. Schweizerische Medizinische Wochenschrift /Journal Suisse de Medecine 1991;121:1585-90 [in German].

7. De Benedittis G, Massei R. 5-HT precursors in migraine prophylaxis: A double-blind cross-over study with L-5-hydroxytryptophan versus placebo. Clin J Pain 1986;3:123-9.

8. Mathew NT. 5-hydroxytryptophan in the prophylaxis of migraine. Headache 1978;18:111-3.

9. Bono G, Criscuoli M, Martignoni E, et al. Serotonin precursors in migraine prophylaxis. Advances in Neurology 1982;33:357-63.

10. De Giorgis G, Miletto R, Iannuccelli M, et al. Headache in association with sleep disorders in children: A psychodiagnostic evaluation and controlled clinical study n L-5-HTP versus placebo. Drugs Exp Clin Res 1987;13:425-33.

11. Santucci M, Cortelli P, Rossi PG, et al. L-5-Hydroxytryptophan versus placebo in childhood migraine prophylaxis: a double-blind crossover study. Cephalalgia 1986;6:155-7.

Insomnia
Dose: 1 to 2 grams at bedtime The amino acid, L-tryptophan, a serotonin precursor, taken in amounts of 1 to 4 grams at bedtime, has been used successfully for people with insomnia in many studies,1, 2including double-blind trials.3, 4, 5, 6 Some research indicates that people with more severe forms of insomnia may need to take L-tryptophan for several nights before improvement in sleep is noticed.7, 8One controlled trial found that newborns receiving a bottle feeding in which 420 mg of L-tryptophan per 2.2 lbs of body weight had been added entered quiet sleep sooner and slept for a longer time.9 Some preliminary and controlled trials have not found L-tryptophan effective,10 or have found L-tryptophan effective only for people who awaken more frequently at night compared with those who awaken less frequently.11 Several studies combined L-tryptophan with a carbohydrate-containing meal to improve L-tryptophan uptake into the brain.12, 13 A related compound that occurs naturally in the body, 5-HTP is also converted into serotonin and might, therefore, be helpful for insomnia. In a double-blind study of people without insomnia, supplementation with 5-HTP (200 mg at 9:15 p.m. and 400 mg at 11:15 p.m.) increased rapid-eye-movement (REM) sleep, presumably indicating improved sleep quality.14 In a preliminary study of people with fibromyalgia, supplementing with 100 mg of 5-HTP three times a day improved sleep quality.15 However, additional research is needed to determine whether 5-HTP is safe and effective for people with insomnia.In a preliminary study, 5-HTP was also found to be an effective treatment for "sleep terrors,"16 a common problem in children that causes sudden awakening with persistent fear or terror, screaming, sweating, confusion, and increased heart rate.
References

1. Fitten LJ, Profita J, Bidder TG. L-tryptophan as a hypnotic in special patients. J Am Geriatr Soc 1985;33:294-7.

2. Schneider-Helmert D, Spinweber CL. Evaluation of L-tryptophan for treatment of insomnia: A review. Psychopharmacology (Berlin) 1986;89(1):1-7.

3. Demisch K, Bauer J, Georgi K, Demisch L. Treatment of severe chronic insomnia with L-tryptophan: results of a double-blind cross-over study. Pharmacopsychiatry. 1987;20:242-4.

4. Hudson C, Hudson SP, Hecht T, MacKenzie J. Protein source tryptophan versus pharmaceutical grade tryptophan as an efficacious treatment for chronic insomnia. Nutr Neurosci 2005;8:121-7.

5. Spinweber C. L-Tryptophan administered to chronic sleep-onset insomniacs: Late-appearing reduction of sleep latency. Psychopharmacology 1986;90:151-5.

6. Spinweber CL, Ursin R, Hilbert RP, Hilderbrand RL. L-tryptophan: effects on daytime sleep latency and the waking EEG. Electroencephalogr Clin Neurophysiol 1983;55:652-61.

7. Hartmann E, Lindsley JG, Spinweber C. Chronic insomnia: effects of tryptophan, flurazepam, secobarbital, and placebo. Psychopharmacology (Berl) 1983;80:138-42.

8. Schneider-Helmert D, Spinweber CL. Evaluation of L-tryptophan for treatment of insomnia: A review. Psychopharmacology (Berlin) 1986;89(1):1-7.

9. Yogman MW, Zeisel SH. Diet and sleep patterns in newborn infants. N Engl J Med 1983;309:1147-9.

10. Hartmann E. Effects of L-tryptophan on sleepiness and on sleep. J Psychiatr Res 1982-3;17:107-13 [review].

11. Lindsley JG, Hartmann EL, Mitchell W. Selectivity in response to L-tryptophan among insomniac subjects: a preliminary report. Sleep 1983;6:247-56.

12. Hudson C, Hudson SP, Hecht T, MacKenzie J. Protein source tryptophan versus pharmaceutical grade tryptophan as an efficacious treatment for chronic insomnia. Nutr Neurosci 2005;8:121-7.

13. Fernstrom JD, Faller DV. Neutral amino acids in the brain: Changes in response to food ingestion. J Neurochem 1978;30:1531-8.

14. Puttini PS, Caruso I. Primary fibromyalgia syndrome and 5-hydroxy-L-tryptophan: a 90-day open study. J Int Med Res 1992;20:182-9.

15. Bruni O, Ferri R, Miano S, Verrillo E. L-5-Hydroxytryptophan treatment of sleep terrors in children. Eur J Pediatr 2004;163:402-7.

16. Kimball RW, Friedman AP, Vallejo E. Effect of serotonin in migraine patients. Neurology 1960;10:107-11.

Restless Legs Syndrome
Dose: 1 to 2 grams at bedtime Since restless legs syndrome is often accompanied by insomnia, and L-tryptophan has been helpful for promoting sleep,1 one investigator treated two patients having both restless legs syndrome and insomnia with 1 to 2 grams of L-tryptophan at bedtime.2 In both cases restless legs symptoms improved as well as insomnia. Controlled research is needed to confirm these findings.
References

1. Sandyk R. L-tryptophan in neuropsychiatric disorders: a review. Int J Neurosci 1992;67:127-44 [review].

2. Sandyk R. L-Tryptophan in the treatment of restless legs syndrome. Am J Psychiatry 1986;143:554-5.

Premenstrual Syndrome
Dose: 2 to 6 grams per day, during the second half of the menstrual cycle Preliminary research suggests that imbalances of the neurotransmitter serotonin or its precursor, L-tryptophan, may be associated with PMS.1 In a double-blind trial, women with PMS who took 6 grams per day of L-tryptophan during the second half of their menstrual cycle reported a one-third reduction in the severity of abnormal mood symptoms.2 This confirmed the results of an earlier preliminary trial in which 2 grams per day of L-tryptophan taken during the second half of the menstrual cycle reduced depression and other symptoms associated with PMS.3
References

1. Menkes DB, Coates DC, Fawcett JP. Acute tryptophan depletion aggravates premenstrual syndrome. J Affect Disord 1994;32:37-44.

2. Steinberg S, Annable L, Young SN, Liyanage N. A placebo-controlled clinical trial of L-tryptophan in premenstrual dysphoria. Biol Psychiatry 1999;45:313-20.

3. Steinberg S, Annable L, Young SN, Belanger MC. Tryptophan in the treatment of late luteal phase dysphoric disorder: a pilot study. J Psychiatry Neurosci 1994;19 :114-9.

Bulimia
Dose: Refer to label instructions

Serotonin, a hormone that helps regulate food intake and appetite, is synthesized in the brain from the amino acid L-tryptophan. Preliminary data suggest that some people with bulimia have low serotonin levels.1 Researchers have reported that bulimic women with experimentally induced tryptophan deficiency tend to eat more and become more irritable compared to healthy women fed the same diet,2, 3 though not all studies have demonstrated these effects.4

Weight-loss diets result in lower L-tryptophan and serotonin levels in women,5 which could theoretically trigger bingeing and purging in susceptible people. However, the benefits of L-tryptophan supplementation are unclear. One small, double-blind trial reported significant improvement in eating behavior, feelings about eating, and mood among women with bulimia who were given 1 gram of L-tryptophan and 45 mg of vitamin B6 three times per day.6 Other double-blind studies using only L-tryptophan have failed to confirm these findings.7, 8 L-tryptophan is available by prescription only; most drug stores do not carry it, but "compounding" pharmacies do. Most cities have at least one compounding pharmacy, which prepares customized prescription medications to meet individual patient's needs.

References

1. Kaye WH, Weltzin TE. Serotonin activity in anorexia and bulimia nervosa: relationship to the modulation of feeding and mood. J Clin Psychiatry 1991;52 Suppl:41-8 [review].

2. Smith KA, Fairburn CG, Cowen PJ. Symptomatic relapse in bulimia nervosa following acute tryptophan depletion. Arch Gen Psychiatry 1999;56:171-6.

3. Weltzin TE, Fernstrom MH, Fernstrom JD, et al. Acute tryptophan depletion and increased food intake and irritability in bulimia nervosa. Am J Psychiatry 1995;152:1668-71.

4. Oldman AD, Walsh AES, Salkovskis P, et al. Biochemical and behavioural effects of acute tryptophan depletion in abstinent bulimic subjects: a pilot study. Psychol Med 1995;25:995-1001.

5. Anderson IM, Parry-Billings M, Newsholme EA, et al. Dieting reduces plasma tryptophan and alters brain 5-HT function in women. Psychol Med 1990;20:785-91.

6. Mira M, Abraham S. L-tryptophan as an adjunct to treatment of bulimia nervosa. Lancet 1989;ii:1162-3 [letter].

7. Krahn D, Mitchell J. Use of L-tryptophan in treating bulimia. Am J Psychiatry 1985;142:1130 [letter].

8. Brewerton TD, Murphy DL, Jimerson DC. Testmeal responses following m-chlorophenylpiperazine and L-tryptophan in bulimics and controls. Neuropsychopharmacology 1994;11:63-71.

Bulimia
Dose: Refer to label instructions

People with eating disorders who restrict their food intake are at risk for multiple nutrient deficiencies, including protein, calcium, iron, riboflavin, niacin,1folic acid,2vitamin A, vitamin C,3 and vitamin B6,4 and essential fatty acids.5 A general multivitamin-mineral formula can reduce the detrimental health effects of these deficiencies.

Serotonin, a hormone that helps regulate food intake and appetite, is synthesized in the brain from the amino acid L-tryptophan. Preliminary data suggest that some people with bulimia have low serotonin levels.6 Researchers have reported that bulimic women with experimentally induced tryptophan deficiency tend to eat more and become more irritable compared to healthy women fed the same diet,7, 8 though not all studies have demonstrated these effects.9

Weight-loss diets result in lower L-tryptophan and serotonin levels in women,10 which could theoretically trigger bingeing and purging in susceptible people. However, the benefits of L-tryptophan supplementation are unclear. One small, double-blind trial reported significant improvement in eating behavior, feelings about eating, and mood among women with bulimia who were given 1 gram of L-tryptophan and 45 mg of vitamin B6 three times per day.11 Other double-blind studies using only L-tryptophan have failed to confirm these findings.12, 13 L-tryptophan is available by prescription only; most drug stores do not carry it, but "compounding" pharmacies do. Most cities have at least one compounding pharmacy, which prepares customized prescription medications to meet individual patient's needs.

References

1. Thibault L, Roberge AG. The nutritional status of subjects with anorexia nervosa. Int J Vitam Nutr Res 1987;57:447-52.

2. Abou-Saleh MT, Coppen A. The biology of folate in depression: implications for nutritional hypotheses of the psychoses. J Psychiatr Res 1986;20:91-101 [review].

3. Beaumont PJ, Chambers TL, Rouse L, Abraham SF. The diet composition and nutritional knowledge of patients with anorexia nervosa. J Hum Nutr 1981;35:265-73.

4. Rock CL, Vasantharajan S. Vitamin status of eating disorder patients: relationship to clinical indices and effect of treatment. Int J Eat Disord 1995;18:257-62.

5. Langan SM, Farrell PM. Vitamin E, vitamin A and essential fatty acid status of patients hospitalized for anorexia nervosa. Am J Clin Nutr 1985;41:1054-60.

6. Kaye WH, Weltzin TE. Serotonin activity in anorexia and bulimia nervosa: relationship to the modulation of feeding and mood. J Clin Psychiatry 1991;52 Suppl:41-8 [review].

7. Smith KA, Fairburn CG, Cowen PJ. Symptomatic relapse in bulimia nervosa following acute tryptophan depletion. Arch Gen Psychiatry 1999;56:171-6.

8. Weltzin TE, Fernstrom MH, Fernstrom JD, et al. Acute tryptophan depletion and increased food intake and irritability in bulimia nervosa. Am J Psychiatry 1995;152:1668-71.

9. Oldman AD, Walsh AES, Salkovskis P, et al. Biochemical and behavioural effects of acute tryptophan depletion in abstinent bulimic subjects: a pilot study. Psychol Med 1995;25:995-1001.

10. Anderson IM, Parry-Billings M, Newsholme EA, et al. Dieting reduces plasma tryptophan and alters brain 5-HT function in women. Psychol Med 1990;20:785-91.

11. Mira M, Abraham S. L-tryptophan as an adjunct to treatment of bulimia nervosa. Lancet 1989;ii:1162-3 [letter].

12. Krahn D, Mitchell J. Use of L-tryptophan in treating bulimia. Am J Psychiatry 1985;142:1130 [letter].

13. Brewerton TD, Murphy DL, Jimerson DC. Testmeal responses following m-chlorophenylpiperazine and L-tryptophan in bulimics and controls. Neuropsychopharmacology 1994;11:63-71.

Premenstrual Syndrome
Dose: 2 to 6 grams per day, during the second half of the menstrual cycle Preliminary research suggests that imbalances of the neurotransmitter serotonin or its precursor, L-tryptophan, may be associated with PMS.1 In a double-blind trial, women with PMS who took 6 grams per day of L-tryptophan during the second half of their menstrual cycle reported a one-third reduction in the severity of abnormal mood symptoms.2 This confirmed the results of an earlier preliminary trial in which 2 grams per day of L-tryptophan taken during the second half of the menstrual cycle reduced depression and other symptoms associated with PMS.3
References

1. Menkes DB, Coates DC, Fawcett JP. Acute tryptophan depletion aggravates premenstrual syndrome. J Affect Disord 1994;32:37-44.

2. Steinberg S, Annable L, Young SN, Liyanage N. A placebo-controlled clinical trial of L-tryptophan in premenstrual dysphoria. Biol Psychiatry 1999;45:313-20.

3. Steinberg S, Annable L, Young SN, Belanger MC. Tryptophan in the treatment of late luteal phase dysphoric disorder: a pilot study. J Psychiatry Neurosci 1994;19 :114-9.

Depression
Dose: 3 to 6 grams per day

Disruptions in emotional well-being, including depression, have been linked to serotonin imbalances in the brain.1 L-Tryptophan is the precursor to serotonin, and low body levels of L-tryptophan are associated with depression symptoms.2 Furthermore, L-tryptophan supplements have been shown to increase serotonin levels.3 Many uncontrolled studies report that 3 to 6 grams per day of L-tryptophan helps improve mood in depressed people.4, 5 Several controlled trials found that 3 to 6 grams per day of L-tryptophan were equally as effective as antidepressant medications.6, 7 Some,8, 9, 10 though not all,11, 12 double blind studies reported that similar amounts of L-tryptophan were superior to a placebo for improving depression symptoms. Trials using amounts above 6 grams per day of L-tryptophan have often found no benefit for depression, suggesting that 3 to 6 grams per day is optimum.13 5-Hydroxytryptophan (5-HTP), a breakdown product of L-tryptophan and a serotonin precursor, has also been studied as a treatment for depression. Some trials using 200 to 300 mg per day of 5-HTP with people suffering from depression have shown signs of efficacy.14, 15, 16, 17, 18, 19 However, much of the research was either uncontrolled or used 5-HTP in combination with antidepressant drugs. Depressed people interested in considering 5-HTP should consult a doctor.

References

1. Stockmeier CA: Neurobiology of serotonin in depression and suicide. Ann N Y Acad Sci 1997, 836:220-32.

2. Eccleston D. L-tryptophan and depressive illness: a valuable adjunct to therapy? Psychiatric Bulletin 1993;17:223-4 [review].

3. Young SN, Teff KL. Tryptophan availability, 5HT synthesis and 5HT function. Prog Neuropsychopharmacol Biol Psychiat 1989;13:373-9.

4. Werbach MR. Nutritional influences on mental illness, 2nd ed. Tarzana, CA: Third Line Press, 1999, 266-67 [review].

5. Buist R: The therapeutic predictability of tryptophan and tyrosine in the treatment of depression. Int J Clin Nutr Rev 1983;3:1-3 [review].

6. Lindberg D, Ahlfors UG, Dencker SJ, et al. Symptom reduction in depression after treatment with L-tryptophan or imipramine. Item analysis of Hamilton rating scale for depression. Acta Psychiatr Scand 1979;60:287-94.

7. Young SN. The clinical psychopharmacology of tryptophan. In Wurtman RJ, Wurtman JJ, eds. Nutrition and the Brain, Volume 7. New York: Raven Press, 1986, 49-88.

8. Thomson J, Rankin H, Ashcroft GW, et al.The treatment of depression in general practice: a comparison of L-tryptophan, amitriptyline, and a combination of L-tryptophan and amitriptyline with placebo. Psychol Med 1982;12:741-51.

9. Bennie E. Mianserin hydrochloride and Ltryptophan compared in depressive illness. Br J Clin Soc Psych 1982;1:90-1.

10. Jaffe G, Grimshaw J. A placebo-controlled comparison of L-tryptophan and amitriptyline in the treatment of depressive illness in general practice. Br J Clin Soc Psych 1985;3:51-5.

11. Cooper AJ, Datta SR. A placebo controlled evaluation of L-tryptophan in depression in the elderly. Can J Psychiatry 1980;25:386-90.

12. Young SN. The clinical psychopharmacology of tryptophan. In Wurtman RJ, Wurtman JJ, eds. Nutrition and the Brain, Volume 7. New York: Raven Press, 1986, 49-88.

13. Young SN, Chouinard G, Annable L. Tryptophan in the treatment of depression. Adv Exp Med Biol 1981;133:727-37 [review].

14. Angst J, Woggon B, Schoepf J. The treatment of depression with L-5-hydroxytryptophan versus imipramine. Results of two open and one double-blind study. Arch Psychiatr Nervenkr 1977;224:175-86.

15. Nolen WA, van de Putte JJ, Dijken WA, et al. Treatment strategy in depression. II. MAO inhibitors in depression resistant to cyclic antidepressants: two controlled crossover studies with tranylcypromine versus L-5-hydroxytryptophan and nimifensine. Acta Psychiatr Scand 1988;78:676-83.

16. Nolen WA, van de Putte JJ, Dijken WA, Kamp JS. L-5-HTP in depression resistant to re-uptake inhibitors. An open comparative study with tranylcypromine. Br J Psychiatry 1985;147:16-22.

17. D'Elia G, Hanson L, Raotma H. L-tryptophan and 5-hydroxytryptophan in the treatment of depression. A review. Acta Psychiatr Scand 1978;57:239-52 [review].

18. Van Praag HM, Lemus C. Monoamine precursors in the treatment of psychiatric disorders. Nutrition and the Brain, vol. 7, RJ Wurtman, JJ Wurtman, eds. New York: Raven Press, 1986 [review].

19. Van Praag H, de Hann S. Depression vulnerability and 5-hydroxytryptophan prophylaxis. Psychiatry Res 1980;3:75-83.

Seasonal Affective Disorder
Dose: With doctor's supervision, 2 to 4 grams per day, increasing up to 6 grams if no improvement Since disturbances of serotonin metabolism may be part of the cause of SAD,1 and creating a deficiency of L-tryptophan, a precursor of serotonin, worsens symptoms of SAD,2 L-tryptophan supplementation might be helpful. One case report describes a patient with SAD who improved after taking L-tryptophan daily, 1 gram with dinner and 1 gram at bedtime.3 In a small, preliminary study, people with SAD who responded poorly or not at all to bright light therapy were given 3 grams per day of L-tryptophan for two weeks, in addition to light therapy. Nine of 14 people responded well to this combination.4 Another small preliminary study found that one of five SAD patients that did not respond to light therapy did improve after L-tryptophan supplementation in the amount of 4 grams per day, increased to 6 grams per day if no improvement occurred at the lower dose.5 A small controlled trial found that a combination of 1.5 grams of L-tryptophan, 50 mg of vitamin B6, 300 mg vitamin C, and eight ounces of fruit juice, taken three times daily, was more effective for reducing symptoms of SAD than the same combination without L-tryptophan.65-HTP (5-hydroxytryptophan) is a substance related to L-tryptophan that also increases serotonin production and has shown antidepressant activity.7 It may also be useful in the treatment of SAD, but there is currently no research testing this possibility.
References

1. Neumeister A, Konstantinidis A, Praschak-Rieder N, et al. Monoaminergic function in the pathogenesis of seasonal affective disorder. Int J Neuropsychopharmacol 2001;4:409-20.

2. Van der Does AJ. The effects of tryptophan depletion on mood and psychiatric symptoms. J Affect Disord 2001;64:107-19.

3. Levitt AJ, Brown GM, Kennedy SH, Stern K. Tryptophan treatment and melatonin response in a patient with seasonal affective disorder. J Clin Psychopharmacol 1991;11:74-5.

4. Lam RW, Levitan RD, Tam EM, et al. L-tryptophan augmentation of light therapy in patients with seasonal affective disorder. Can J Psychiatry 1997;42:303-6.

5. Ghadirian AM, Murphy BE, Gendron MJ. Efficacy of light versus tryptophan therapy in seasonal affective disorder. J Affect Disord 1998;50:23-7.

6. McGrath RE, Buckwald B, Resnick EV. The effect of L-tryptophan on seasonal affective disorder. J Clin Psychiatry 1990;51:162-3.

7. Birdsall TC. 5-Hydroxytryptophan: a clinically-effective serotonin precursor. Alternative Med Rev 1998;3:271-80.

Anxiety
Dose: Refer to label instructionsAnimal research suggests that the brain chemical serotonin is involved in the mechanisms underlying anxiety,1 and double-blind studies have reported that creating deficiencies of L-tryptophan, a precursor of serotonin, worsens symptoms in people with anxiety disorders.2, 3 A small double-blind trial tested a food bar containing 250 mg of L-tryptophan plus carbohydrate compared with a placebo bar containing only carbohydrate in a people diagnosed with social anxiety disorder.4 The bars were consumed one hour before doing a task designed to provoke anxiety, and anxiety was measured with two tests of heart rate changes and by ratings of anxiety by the participants. Only one of the two heart rate measures showed the L-tryptophan bar was more effective, and only slightly lower anxiety was reported when L-tryptophan was consumed.5 A double blind study in China reported that 3 grams per day of L-tryptophan improved symptoms, including anxiety, in a group of people diagnosed with "neurosis."6 More research is needed to evaluate L-tryptophan as a treatment for anxiety disorders.
References

1. Iversen SD. 5-HT and anxiety. Neuropharmacology 1984;23:1553-60 [review].

2. Schruers K, Klaassen T, Pols H, et al. Effects of tryptophan depletion on carbon dioxide provoked panic in panic disorder patients. Psychiatry Res 2000;93:179-87.

3. Argyropoulos SV, Hood SD, Adrover M, et al. Tryptophan depletion reverses the therapeutic effect of selective serotonin reuptake inhibitors in social anxiety disorder. Biol Psychiatry 2004;56:503-9.

4. Hudson C, Hudson S, MacKenzie J. Protein-source tryptophan as an efficacious treatment for social anxiety disorder: a pilot study. Can J Physiol Pharmacol 2007;85:928-32.

5. Hudson C, Hudson S, MacKenzie J. Protein-source tryptophan as an efficacious treatment for social anxiety disorder: a pilot study. Can J Physiol Pharmacol 2007;85:928-32.

6. Zang DX. A self body double blind clinical study of L-tryptophan and placebo in treated neurosis. Zhonghua Shen Jing Jing Shen Ke Za Zhi 1991;24:77-80,123-4 [in Chinese].

Hypertension
Dose: Refer to label instructionsThe brain chemical serotonin may play a role in blood pressure regulation,1 and animal research suggests L-tryptophan, a precursor of serotonin, might be helpful in the prevention and treatment of hypertension.2, 3, 4 Preliminary human studies suggest that 3 to 4 grams per day of L-tryptophan can lower blood pressure in people with hypertension.5, 6 Double blind trials are needed to confirm these promising reports.
References

1. Lehnert H, Beyer J. Cardiovascular and endocrine properties of L-tryptophan in combination with various diets. Adv Exp Med Biol 1991;294:407-16 [review].

2. Fregly MJ, Lockley OE, Cade JR. Effect of chronic dietary treatment with L-tryptophan on the development of renal hypertension in rats. Pharmacology 1988;36:91-100.

3. Lark LA, Witt PA, Becker KB, et al. Effect of dietary tryptophan on the development of hypertension in the Dahl salt-sensitive rat. Clin Exp Hypertens A 1990;12:1-13.

4. Pop E, Anderson W, Prokai-Tatrai K, et al. Antihypertensive activity of redox derivatives of tryptophan. J Med Chem 1990;33:2216-21.

5. Cade JR, Fregly MJ, Privette M. Effect of tryptophan and 5-hydroxytryptophan on the blood pressure of patients with mild to moderate hypertension. Amino Acids 1992;2:133-42.

6. Lehnert H et al. [Note: Other authors' names not found.] Effects of L-tryptophan on blood pressure in essential hypertensives. Clin Exp Theory Pract 1987;A9:208 [abstract].

Obesity
Dose: Refer to label instructions

Animal research and preliminary human reports suggest that serotonin precursors such as L-tryptophan or 5-HTP (5-hydroxytryptophan) might help control appetite and promote weight loss.1, 2 In a controlled study, increasing L-tryptophan supplementation one hour before a meal from 1 gram to 2 grams to three grams resulted in progressively fewer calories and carbohydrates being consumed during the meal at the higher L-tryptophan dosages.3 While this effect might lead to weight loss over time, a small double-blind trial did not find a significant benefit from taking 1 gram of L-tryptophan before each meal as part of a six-week weight loss program.4 Weight-loss diets result in lower L-tryptophan and serotonin levels in women,5 which could theoretically trigger cravings and make dieting more difficult.6 More research is needed to determine whether L-tryptophan might improve the results of a long-term weight loss diet.

References

1. Morris P, Li ET, MacMillan ML, Anderson GH. Food intake and selection after peripheral tryptophan. Physiol Behav 1987;40:155-63.

2. Caston JC. Clinical applications of l-tryptophan in the treatment of obesity and depression. Adv Ther 1987;4:78-83.

3. Cavaliere H, Medeiros-Neto G. The anorectic effect of increasing doses of L-tryptophan in obese patients. Eat Weight Disord 1997;2:211-5.

4. Strain GW, Strain JJ, Zumoff B. L-tryptophan does not increase weight loss in carbohydrate-craving obese subjects. Int J Obes 1985;9:375-80.

5. Anderson IM, Parry-Billings M, Newsholme EA, et al. Dieting reduces plasma tryptophan and alters brain 5-HT function in women. Psychol Med 1990;20:785-91.

6. Wurtman JJ. The involvement of brain serotonin in excessive carbohydrate snacking by obese carbohydrate cravers. J Am Diet Assoc 1984;84:1004-7.

Attention Deficit-Hyperactivity Disorder
Dose: Refer to label instructionsImbalances in the brain chemical serotonin, or low blood levels of its precursor, L-tryptophan, have been associated with ADHD in some,1 though not all,2 studies.3, 4 Preliminary human studies report that creating deficiencies in L-tryptophan worsens some symptoms of ADHD. A small double blind trial found that giving children with ADHD a daily supplement of 100 mg L-tryptophan per 2.2 pounds body weight per day for one week improved behavior according to parents' ratings, but not teachers' ratings.5 More studies are needed to better evaluate L-tryptophan as a treatment for ADHD.
References

1. Comings DE. Serotonin and the biochemical genetics of alcoholism: lessons from studies of attention deficit hyperactivity disorder (ADHD) and Tourette syndrome. Alcohol Alcohol Suppl 1993;2:237-41 [review].

2. Ferguson HB, Pappas BA, Trites RL, et al. Plasma free and total tryptophan, blood serotonin, and the hyperactivity syndrome: no evidence for the serotonin deficiency hypothesis. Biol Psychiatry. 1981;16:231-8.

3. Stadler C, Zepf FD, Demisch L, et al. Influence of rapid tryptophan depletion on laboratory-provoked aggression in children with ADHD. Neuropsychobiology 2007;56:104-10.

4. Zepf FD, Stadler C, Demisch L, et al. Serotonergic functioning and trait-impulsivity in attention-deficit/hyperactivity-disordered boys (ADHD): influence of rapid tryptophan depletion. Hum Psychopharmacol 2008;23:43-51.

5. Nemzer ED, Arnold LE, Votolato NA, McConnell H. Amino acid supplementation as therapy for attention deficit disorder. J Am Acad Child Psychiatry 1986;25:509-13.

Bipolar Disorder
Dose: Refer to label instructionsL-tryptophan is the amino acid used by the body to produce serotonin, a chemical messenger important for proper brain function. Supplementation with L-tryptophan has led to improvement in depression in many studies,1, 2 but information is limited about its effect on bipolar disorder. Case reports on two bipolar patients treated with lithium or an antidepressant drug described marked improvements when they were given 12 grams daily of L-tryptophan.3, 4 Two trials using 6 grams of L-tryptophan daily for acute mania in patients with bipolar disorder found little or no improvement,5, 6 but another double-blind, controlled study using 9.6 grams daily reported better results.7 L-tryptophan is converted to 5-HTP (5-hydroxytryptophan) before it becomes serotonin in the body. In a controlled trial, 200 mg daily of supplemental 5-HTP had antidepressant effects in bipolar patients, though it was not as effective as lithium.8 In a double-blind trial, patients with bipolar disorder had greater improvement with a combination of 5-HTP at 300 mg daily plus an antidepressant drug than with 5-HTP alone.9
References

1. Young SN. Behavioral effects of dietary neurotransmitter precursors: basic and clinical aspects. Neurosci Biobehav Rev 1996;20:313-23 [review].

2. Riemann D, Vorderholzer U. Treatment of depression and sleep disorders. Significance of serotonin and L-tryptophan in pathophysiology and therapy. Fortschr Med 1998;116:40-2 [review].

3. Chouinard G, Jones BD, Young SN, Annable L. Potentiation of lithium by tryptophan in a patient with bipolar illness. Am J Psychiatry 1979;136:719-20.

4. Hedaya RJ. Pharmacokinetic factors in the clinical use of tryptophan. J Clin Psychopharmacol 1984;4:347-8.

5. Prange AJ, Wilson IC, Lynn CW, et al. L-tryptophan in mania: contribution to a permissive hypothesis of affective disorders. Arch Gen Psychiatry 1974;30:56-62.

6. Chambers CA, Naylor GJ. A controlled trial of L-tryptophan in mania. Br J Psychiatry 1978;132:555-9.

7. Murphy DL, Maker M, Goodwin FK, et al. L-tryptophan in affective disorders: indoleamine changes and differential clinical effects. Psychopharmacologia 1974;34:11-20.

8. van Praag HM, de Haan S. Chemoprophylaxis of depressions. An attempt to compare lithium with 5-hydroxytryptophan. Acta Psychiatr Scand Suppl 1981;290:191-201.

9. Mendlewicz J, Youdim MB. Antidepressant potentiation of 5-hydroxytryptophan by L-deprenil in affective illness. J Affect Disord 1980;2:137-46.

Schizophrenia
Dose: 1 to 8 grams per day (under a doctor's supervision) Metabolism of the amino acid L-tryptophan may be abnormal in schizophrenia,1 and initially low blood levels of L-tryptophan rise when symptoms of schizophrenia improve but remain low in cases of poor recovery.2 L-tryptophan supplementation has occasionally been helpful for specific symptoms associated with schizophrenia. A small double-blind trial found that 4 to 8 grams per day of L-tryptophan reduced aggressive symptoms.3 Another double-blind trial found 1 gram per day of L-tryptophan improved memory function in schizophrenics.4 Schizoaffective disorder has features of both schizophrenia and mood disorders. A preliminary study reported that 8 grams per day of L-tryptophan improved mood symptoms in a group of patients with schizoaffective disorder, and a small, double-blind trial found that adding 9 grams per day of L-tryptophan to drug therapy was more effective for stabilizing mood in schizoaffective disorder than drug therapy plus a placebo.5 In contrast, other symptoms of schizophrenia have not responded to L-tryptophan in amounts from 1 to 20 grams per day, according to double-blind studies.6, 7 In fact, a small preliminary study reported that schizophrenic patients on a low-tryptophan diet had improved scores on certain tests of brain function and also had small improvements in psychotic symptoms.8
References

1. Payne IR, Walsh EM, Whittenburg EJ. Relationship of dietary tryptophan and niacin to tryptophan metabolism in schizophrenics and nonschizophrenics. Am J Clin Nutr 1974;27:565-71.

2. Gilmour DG, Manowitz P, Frosch WA, Shopsin B. Association of plasma tryptophan levels with clinical change in female schizophrenic patients. Biol Psychiatry 1973;6:119-28.

3. Morand C, Young SN, Ervin FR. Clinical response of aggressive schizophrenics to oral tryptophan. Biol Psychiatry 1983;18:575-8.

4. Levkovitz Y, Ophir-Shaham O, Bloch Y, et al. Effect of L-tryptophan on memory in patients with schizophrenia. J Nerv Ment Dis 2003;191:568-73.

5. Brewerton TD, Reus VI. Lithium carbonate and L-tryptophan in the treatment of bipolar and schizoaffective disorders. Am J Psychiatry 1983;140:757-60.

6. Levkovitz Y, Ophir-Shaham O, Bloch Y, et al. Effect of L-tryptophan on memory in patients with schizophrenia. J Nerv Ment Dis 2003;191:568-73.

7. Gillin JC, Kaplan JA, Wyatt RJ. Clinical effects of tryptophan in chronic schizophrenic patients. Biol Psychiatry 1976;11:635-9.

8. Rosse RB, Schwartz BL, Zlotolow S, et al. Effect of a low-tryptophan diet as an adjuvant to conventional neuroleptic therapy in schizophrenia. Clin Neuropharmacol 1992;15:129-41.

Anxiety
Dose: Refer to label instructionsAnimal research suggests that the brain chemical serotonin is involved in the mechanisms underlying anxiety,1 and double-blind studies have reported that creating deficiencies of L-tryptophan, a precursor of serotonin, worsens symptoms in people with anxiety disorders.2, 3 A small double-blind trial tested a food bar containing 250 mg of L-tryptophan plus carbohydrate compared with a placebo bar containing only carbohydrate in a people diagnosed with social anxiety disorder.4 The bars were consumed one hour before doing a task designed to provoke anxiety, and anxiety was measured with two tests of heart rate changes and by ratings of anxiety by the participants. Only one of the two heart rate measures showed the L-tryptophan bar was more effective, and only slightly lower anxiety was reported when L-tryptophan was consumed.5 A double blind study in China reported that 3 grams per day of L-tryptophan improved symptoms, including anxiety, in a group of people diagnosed with "neurosis."6 More research is needed to evaluate L-tryptophan as a treatment for anxiety disorders.
References

1. Iversen SD. 5-HT and anxiety. Neuropharmacology 1984;23:1553-60 [review].

2. Schruers K, Klaassen T, Pols H, et al. Effects of tryptophan depletion on carbon dioxide provoked panic in panic disorder patients. Psychiatry Res 2000;93:179-87.

3. Argyropoulos SV, Hood SD, Adrover M, et al. Tryptophan depletion reverses the therapeutic effect of selective serotonin reuptake inhibitors in social anxiety disorder. Biol Psychiatry 2004;56:503-9.

4. Hudson C, Hudson S, MacKenzie J. Protein-source tryptophan as an efficacious treatment for social anxiety disorder: a pilot study. Can J Physiol Pharmacol 2007;85:928-32.

5. Hudson C, Hudson S, MacKenzie J. Protein-source tryptophan as an efficacious treatment for social anxiety disorder: a pilot study. Can J Physiol Pharmacol 2007;85:928-32.

6. Zang DX. A self body double blind clinical study of L-tryptophan and placebo in treated neurosis. Zhonghua Shen Jing Jing Shen Ke Za Zhi 1991;24:77-80,123-4 [in Chinese].

L-Tryptophan is an essential amino acid that the body requires to synthesize proteins and specialized molecules such as the neurotransmitter serotonin. Serotonin appears to play significant roles in sleep, emotional moods, pain control, inflammation, intestinal peristalsis, and other body functions.1

Copyright 2014 Aisle7. All rights reserved. Aisle7.com

The information presented in Aisle7 is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires June 2015.

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NOW NUTRITIONNow® L-Citrulline
 
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    5.0

    Great Great product

    By BRKelley70

    from Alton, IL

    About Me Competitive Athlete, Runner

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      Comments about NOW NUTRITION Now® L-Citrulline:

      Great product. I started taking this product to help with some minor ED issues. This product has giving me great results. And on another note for guys facing the same thing. Avocado and sweet potatoes have given me great results and this product, in conjunction, have given me great results. I have noticed that I have more energy. On another note, I regularly take my blood pressure and have readings around 127/85. 3 days after taking this product I began having readings of 106/65 with a heart rate of 65. I was a little scared and didn't know what would cause this and I speculated that it could be the L citrulline. Unbeknownst to me that, indeed, this was a positive result of the l citrulline. I take this product around 7 am and 12 hours later at 7 pm. This product states that it has no side effects but I would notice that my aggression has increased. I do not know if that is being caused by this product but it is a heck of an coincidence. This effect has been minor. Hope this has been helpful.

      (3 of 5 customers found this review helpful)

       
      5.0

      I will buy this product again!

      By tbrks7

      from Athens, GA

      About Me Exercise Daily

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      • Helps With Fatigue
      • Tastes Fine

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        • Post-workout
        • Pre-workout

        Comments about NOW NUTRITION Now® L-Citrulline:

        I mix this in a pre-workout drink. I take another dose in the evening. It mixes very well and does not effect the taste. I have noticed no negatives so far.

        (3 of 5 customers found this review helpful)

         
        5.0

        I have bought this product again.

        By jancicjw

        from Highland, Indiana

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          Comments about NOW NUTRITION Now® L-Citrulline:

          I take this product before bed.
          It's converted to L-Arginine.
          L-Arginine is converted to Nitric Oxide.
          Great for you when your body is at rest.

          (1 of 9 customers found this review helpful)

           
          3.0

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          By confer1

          from Wichita, KS

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            Comments about NOW NUTRITION Now® L-Citrulline:

            1st time user. Using with L-Arginie. Too soon to conclude if effective. The purchase process is acceptible. Wish it were available in my local store.

            Not ready to say not to buy.

            Chris

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