L-Citrulline (Citrulline malate) is an amino acid that has been shown to improve energy levels, exercise capacity, blood sugar regulation, erectile function, cardiac health, and cancer risk.
This article will explain its role in the human body and share evidence about its benefits.
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Like other amino acids, L-citrulline is a naturally-occurring constituent of protein. It is an amino acid that the body can make internally, but in some situations the body makes less than ideal amounts.
Unlike other amino acids, L-citrulline is not used in protein synthesis and little of it is found in dietary sources. Small amounts are found in melons and cucumbers. In fact the latin name for watermelon is Citrullus lanatus and is based on its known L-Citrulline content.
Each pound of watermelon flesh contains roughly 1000 mg of L-Citrulline which is enough to be helpful.
L-citrulline’s most important effects relate to its role in nitric oxide metabolism. The formation of nitric oxide.
Nitric oxide is a compound made in the body that regulates the immune system and circulation. In the immunity it helps the body recognize infections and lower inflammation. In the circulatory system, nitric oxide helps blood vessels open.
How well the blood vessels open, or dilate, determines how well blood reaches your tissue. This in term can determine how well tissues heal and how well they can generate energy.
Arginine is an amino acid that has been used to improve nitric oxide but recent data suggest that L-Citrulline raises arginine levels more effectively than arginine supplements because they allow it to be recycled.
The human body generates the toxin ammonia as a byproduct from metabolism. It is detoxified by the urea cycle which depends on the amino acids L-citrulline, L-ornithine, and L-arginine.
When nitric oxide levels increase, blood flow to muscles improves, raising physical energy and recovery from activity.
L-Citrulline supplements have been shown to improve strength and lower fatigue symptoms.
In a study on L-Citrulline and female strength, female athletes took L-Citrulline or placebo on two separate occasions. Those supplementing with L-Citrulline showed more upper body and lower body strength without increased exertion as measured by heart rate. They were able to generate more energy without pushing themselves harder3.
In older adults, supplementing with L-citrulline was shown to improve physical performance. It allowed them to train at higher intensities for longer durations. L-citrulline supplementation also helped them burn fat more effectively. In fact, those taking it were able to burn fat better than those doing high-intensity interval training (HIIT)4.
As mentioned above, many foods contain L-Citrulline, but only watermelon contains it in amounts that may be clinically useful.
It is found in significant amounts in normal red watermelon, both seeded and seedless as well as yellow-fleshed watermelon. Less significant amounts are found in casaba melon, cucumbers, cantaloupe, pumpkin, and squash.
A minimally therapeutic serving of watermelon is roughly 10-16 ounces of flesh twice daily. Watermelon juice also contains L-Citrulline.
In the Adrenal Energy formula, I combined L-Citrulline with other ingredients to heighten their effects on energy output. The blend itself can raise energy, improve exercise capacity, and boost mental alertness.
The formula works to boost energy by several different approaches including:
It can be used by all non-pregnant adults without fear of causing unwanted changes to their cortisol levels. That means that even if you are not aware of where your cortisol is at, you can benefit adrenal health and energy levels with Adrenal Energy.
The recommended dosage is 2 capsules once daily in the morning with food.
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1 – Aguayo E, Martínez-Sánchez A, Fernández-Lobato B, Alacid F. L-Citrulline: A Non-Essential Amino Acid with Important Roles in Human Health. Applied Sciences. 2021; 11(7):3293. https://doi.org/10.3390/app11073293
2 – Aguayo E, Martínez-Sánchez A, Fernández-Lobato B, Alacid F. L-Citrulline: A Non-Essential Amino Acid with Important Roles in Human Health. Applied Sciences. 2021; 11(7):3293. https://doi.org/10.3390/app11073293
3 – Glenn JM, Gray M, Wethington LN, Stone MS, Stewart RW Jr, Moyen NE. Acute citrulline malate supplementation improves upper- and lower-body submaximal weightlifting exercise performance in resistance-trained females. Eur J Nutr. 2017 Mar;56(2):775-784. doi: 10.1007/s00394-015-1124-6. Epub 2015 Dec 11. PMID: 26658899.
4 – F B, L P C, V M, M D, G HB, G G, P G, P N, M AL. High intensity interval training combined with L-citrulline supplementation: Effects on physical performance in healthy older adults. Exp Gerontol. 2020 Oct 15;140:111036. doi: 10.1016/j.exger.2020.111036. Epub 2020 Jul 25. PMID: 32721549.
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Dr. Alan Glen Christianson (Dr. C) is a Naturopathic Endocrinologist and the author of The NY Times bestselling Adrenal Reset Diet, The Metabolism Reset Diet and The Thyroid Reset Diet.
Dr. C’s gift for figuring out what really works has helped hundreds of thousands of people reverse thyroid disease, lose weight, diabetes, and regain energy. Learn more about the surprising story that started his quest.
Dr. Alan Christianson
Alan Christianson is a Naturopathic Medical Doctor (NMD) who is a board-certified Naturopathic Endocrinologist with a focus on thyroid disorders. He is the author of The Metabolism Reset Diet and the New York Times bestselling book The Adrenal Reset Diet.
He founded Integrative Health, a physician group dedicated to helping people with thyroid disease and weight-loss resistance regain their health.
He has been named a Top Doctor in Phoenix magazine and has appeared on national TV shows and in numerous print media.
Dr. Christianson resides in the woods by a lake in Northern Minnesota with his wife Kirin.
