Background: Gyms and health stores across the globe promote workout supplements as a way of enhancing performance and promoting faster results. This has created a multi-billion dollar industry in which companies often promote products with bold claims. Arginine is a non-essential amino acid, meaning that the majority of arginine needed can be produced in the body without dietary supplementation. It can be found in a wide variety of foods such as dairy products, beef, seafood, and several plant sources. Arginine-based products, often referred to as nitric oxide supplements, are examples of supplements thought to improve athletic performance. These products claim to increase the ability of the body to make creatine, release growth hormone, and enhance blood flow by increasing nitric oxide production. Although arginine supplementation is common among both athletic and recreationally active populations, increasing controversy is arising over the effectiveness of arginine in enhancing exercise. Numerous studies investigating the performance enhancing effects of arginine have found no beneficial effects despite sound theory (Campbell et al., 2004; Fahs et al., 2009; Greer et al., 2011; Lambert et al, 1993; Mariotti et al., 2007; Tang et al., 2010; Walberg-Rankin et al., 1994); however, conflicting findings still exist (Colombani et al, 1999). Even though creatine, growth hormone, and nitric oxide are important in optimizing exercise effectiveness, little evidence appears to support the use of arginine as a way to enhance exercise performance.
The Best and Latest Evidence on Arginine Supplementation: During the first 10 seconds of exercise, the body relies on creatine to maintain high intensity. Theoretically, increasing creatine concentrations in the muscle will help maintain energy availability. Arginine is one of the amino acids involved in synthesizing creatine. Creatine supplementation has been demonstrated to increase muscular strength, increase muscle size, and improve performance in a variety of sports (Bemben et al, 2005; Demant et al., 1999; Kreider, 2003; Kreider, 2003; Mesa et al., 2002). Arginine is often suggested as a way to enhance the body’s ability to make creatine without the need for creatine supplementation; however, there are no studies demonstrating this capability. Since our body has an excess of arginine to make creatine, it seems unlikely that arginine supplementation would provide any benefits in enhancing the body’s production of creatine (Campbell, 2004). In essence, arginine is unlikely to give the same benefit as creatine supplementation in prolonging the initial intensity of short bouts of activity.
Growth hormone increases cell growth in the body. Increased growth hormone is usually associated with growth of muscle cells. Numerous studies have demonstrated the ability of high doses (12 g to 30 g) of intravenous arginine supplementation to enhance the release of growth hormone (Alba-Roth, 1988). Investigations of oral supplementation, however, demonstrate conflicting findings. One study investigating arginine supplementation (15 grams for 14 days) found growth hormone levels to be elevated above what would be considered normal post-exercise levels (Colombani et al, 1999). A more recent study found that there appears to be no additional effect of growth hormone on muscle when levels are enhanced by arginine supplementation (Tang et al., 2010). In contrast, Abel and associates (2005) found that oral arginine supplementation (5.7 grams) did not affect growth hormone levels and provided no increase in endurance exercise performance. Further research on resistance-trained subjects has found that ingestion of up to 8 grams of arginine for 17 days provides no changes in growth hormone levels (Lambert et al, 1993 & Walberg-Rankin et al, 1994). To make matters worse, arginine ingestion of 30 grams per day was shown to lead to decreases in other hormones that lead to muscle growth, such as IGF-1 (Blazejewski, 2009). Essentially, arginine ingestion may enhance growth hormone release at doses around 15 grams or higher; however, this appears to offer little benefit to exercise performance in the short term and possible negative effects in the long term.
In response to exercise or other stressful events, the body expands the diameter of blood vessels to increase blood flow to certain parts of the body. It does this by producing and releasing nitric oxide in the blood vessels. Arginine is a precursor to the synthesis of nitric oxide. The body uses nitric oxide to increase blood flow by increasing blood vessel diameter. By potentially improving blood flow, arginine is claimed to promote improvements in strength, power, and muscle recovery (Alvares, 2011). Arginine has been shown to increase nitric oxide production when injected in high doses of at least 30 grams; however, the effects of oral supplementation are not as apparent. Numerous studies investigating arginine supplementation found no contribution to enhancing nitric oxide production (Fahs et al, 2009; Greer et al, 2011; Mariotti, 2007). An investigation into the necessary dosages of arginine found that one would have to consume approximately 43 grams of arginine to stimulate the same levels of nitric oxide production as when supplemented intravenously. Furthermore, such high doses of arginine would lead to cramping and stomach pain during exercise (Tang et al., 2010). It has also been suggested that arginine supplementation could lessen the sensitivity of blood vessels to nitric oxide, thus potentially inhibiting performance (Mariotti, 2007). Clearly, arginine ingestion provides little benefit in enhancing blood flow and may even be counterproductive.
Arginine has had many bold claims attached to it. The theoretical benefits of increasing blood flow, enhancing growth hormone release, and enhance creatine production have made it a popular supplement for people of all ages and athletic backgrounds. None-the-less, the effectiveness of arginine supplementation as a way to improve exercise performance has been a controversial subject. Despite numerous studies demonstrating a lack of beneficial effects, conflicting findings still exist. However, it must be remembered that only high doses of arginine (>15 grams) relate to improved growth hormone release profile, and possibly up to 43 grams to influence blood flow. Furthermore, because arginine may create tolerance-related side effects, supplementation should be avoided or taken for very short periods of time. In addition to the lack of benefits with respect to growth hormone and nitric oxide, arginine has not been shown to increase or promote further creatine synthesis. Thus, creatine supplementation is likely a more effective way to increase the storage and utilization of creatine. In conclusion, there does not appear to be sufficient evidence to support using arginine to enhance exercise performance.
Take away points and Health Tips:
- Arginine is a non-essential amino acid that is produced in the body and can also be found in a variety of foods.
- Arginine or nitric oxide supplements often claim to promote increased blood flow, increased internal creatine synthesis, and increased growth hormone production.
- Ingestion of arginine is not an effective way to enhance your body’s ability to make growth hormone.
- Increasing exercise intensity and avoiding high fat diets could provide an increased growth hormone response to exercise, rather than supplementation.
- Ingestion of arginine does not appear to increase blood flow.
- Ingestion or intravenous use of arginine may decrease your ability to increase muscle size with long-term use.
- It is probably best to avoid excess arginine supplementation unless instructed by a health care practitioner.