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Modified GRF 1-29


Mod GRF increases natural growth hormone production, promoting muscle growth, fat loss, flexibility, better recovery, and improved overall health and wellness.

What is Modified GRF 1-29?

Mod-GRF 1-29 is a synthetically made version of growth hormone releasing hormone (GHRH), the chemical in the body responsible for stimulating natural growth hormone production. Sometimes referred to as CJC-1295 without DAC, it is categorized as a growth hormone secretagogue, a compound which stimulates increased secretion of growth hormone from the pituitary gland. Although similar to Sermorelin, Mod-GRF has four amino acid substitutions made to its chemical structure, hence the alternate name “tetrasubstituted” GRF 1-29. These changes effectively increase the stability of Mod GRF during storage, transportation, and administration while enhancing its affinity for the GHRH receptor.

Like the body’s natural GHRH, Mod-GRF works by binding to the growth hormone releasing hormone receptor (or GHRHr) in the anterior part of the pituitary gland. There, it works to amplify the pulsatile release of GH, consequently provoking increases in production of IGF-1 as well. Mod GRF works most effectively when administered at the same time as a release of GH in the body. This can be accomplished by timing administration with the body’s natural GH release or by administering it along with a GHRP to further amplify both peptides’ effects. (Read more below under “Synergistic Combination with Growth Hormone Releasing Peptides.”)

As it exerts its effects in a similar manner to GHRH, Modified GRF’s positive effect on GH output is modulated by a negative feedback mechanism initiated by somatostatin, the endogenous hormone also known as growth hormone inhibiting hormone (GHIH). This has several positive effects, the first of which is the prevention of extreme, unhealthy GH levels in the body. Second, it allows for more natural patterns of fluctuation in GH concentrations. These both help to avoid negative side effects that often accompany the administration of artificial hGH.

Additionally, its natural action mechanism allows for the preservation of the hypothalamic-pituitary-somatotropic axis, preventing the shutdown of hormone production that typically accompanies direct replacement with synthetic hGH. Further, it has also been shown to improve sleep quality, enhancing the duration of restorative slow wave sleep and amplifying sleep-related secretion of growth hormone while reducing production of cortisol (a catabolic stress hormone).

Also Known As: Tetrasubstituted Growth Releasing Factor 1-29

Amino Acid Sequence: Ac-His-D-Ph)-Asp-Ala-Val-Phe-Thr-Asn-Ser-Tyr-Arg-Lys-Val-Leu-Lys-Arg-Leu-Ser-Ala-Arg-Lys-Leu-Leu-Gln-Asp-Ile-Leu-NH2

Molecular Formula:

Molar Mass: 3273.9


Mod GRF 1-29 stimulates increased natural growth hormone production. This promotes greater muscle and lean body mass, decreased body fat, and enhanced recovery from injuries and training sessions. In addition, it promotes deeper, more restful sleep, enhanced flexibility and joint health, and improved overall health and wellness. Growth hormone is a crucial component in numerous physiological processes, with substantial influence in the facilitation of strength, energy, flexibility, vitality, and overall well-being. Indeed, aging-related decline in growth hormone production is responsible for many of the debilitating effects commonly associated with getting older.

Enhanced growth hormone (GH) levels also stimulate greater production of Insulin-like Growth Factor 1 (IGF-1) in the body, further driving improvements in body composition with accelerated growth of muscle tissue. Importantly, as Mod-GRF stimulates the body’s natural growth hormone output, none of the negative side effects often associated with synthetic hGH administration typically occur. This avoids the shutdown of natural growth hormone production as well as adverse effects like acromegaly and carpal tunnel syndrome, conditions that typically arise from extreme, unnatural amounts of GH in the body.

To increase growth hormone levels, Mod GRF stimulates the pituitary gland to produce greater amounts of natural GH. Critically, Modified GRF stimulates natural, endogenous production and is not simply synthetic hGH, a fact which offers several important advantages. First, overdoses are virtually impossible, as its effects are mediated with negative feedback by the body’s own regulatory mechanisms. As a result, GH production is unable to reach dangerously high levels, and many of the previously mentioned negative side effects of synthetic hGH administration are avoided. Second, the body’s own production of growth hormone is enhanced, not shut down as with administration of exogenous hGH. Therefore, there is no risk of a hormonal crash upon stopping Mod GRF administration.

Third, there is also no likelihood of a diminishing response to administration as there is with artificial hGH. This is due to Modified GRF’s promotion of enhanced yet natural levels of growth hormone in the body. When synthetic hGH is administered, it causes growth hormone levels to spike and remain unnaturally constant, which can result in its effectiveness diminishing rapidly over time as the body becomes desensitized to its effects. In maintaining blood levels that more closely resemble the body’s natural fluctuations, Mod GRF remains consistently effective at a given dose.

Difference Between Mod-GRF and CJC-1295 DAC

Both peptides are synthetic variations of GHRH and act to amplify the pulsatile release of GH in the body. The main difference between the two is that CJC-1295 has a much longer duration of action in the body, with levels remaining elevated for as much as a week, while Mod-GRF’s effects last for only around 30 minutes. As mentioned previously, this shorter duration mirrors natural patterns much more closely and may help to avoid unwanted side effects, especially when used long term. However, CJC-1295’s long lasting effects can have advantages in certain situations as well, specifically for performance enhancement. Ultimately, the purpose of administration will decide which peptide is more suited for a particular individual (for example, long-term anti-aging benefits vs. shorter-term athletic improvement).

Synergistic Combination With Growth Hormone Releasing Peptides (GHRPs)

To achieve even higher levels of natural growth hormone output, Mod GRF is often taken in combination with a growth hormone releasing peptide (GHRP) such as GHRP-2, GHRP-6, Ipamorelin, or Hexarelin, as they possess complimentary mechanisms of action. While a GHRH peptide like Mod GRF amplifies the pulse of GH release, a GHRP is able to initiate that pulse. Further, GHRPs lower somatostatin, the hormone in the body responsible for inhibiting growth hormone production. As a result, this synergy boosts GH very effectively, enabling substantial increases in growth hormone levels for the duration of administration. This can result in significant performance enhancing effects such as faster muscle tissue growth and repair, significantly improved wound healing and recovery, and considerable gains in flexibility, strength, and endurance.


Amount per administration: 100mcg
Administration frequency: 1 to 3 times daily

Mod GRF is generally administered 1-3 times daily at dosages of 100mcg per administration. For anti-aging purposes, 100mcg can be administered once daily before bed. This protocol can provide a significant increase in growth hormone production over time while still mirroring natural patterns of GH release. For strength gain or performance enhancement, 100mcg can be administered 3 times a day in combination with a GHRP (as mentioned above). The higher dosage of Mod GRF in conjunction with the use of a GHRP can provide a substantial increase in growth hormone output. This will facilitate muscle growth, fat loss, and recovery from training and injury.

Importantly, dosages should always be monitored and adjusted by the prescribing physician based on individual results. It is a good practice to start with a more conservative dose at first, increasing only as needed to attain desired results. This helps to avoid excessive doses that can lead to unwanted side effects.

Side Effects

Side effects of Mod GRF are typically mild and dose-dependent, with negative effects rarely occurring at moderate dosage levels. Generally, mild flushing, nausea, stomach upset, dizziness, and/or headache may occur upon initial administration. These reactions tend to dissipate after repeated injections. Feelings of tiredness or lethargy are possible as well, as growth hormone can increase the desire for sleep as well as its quality and restorative capabilities.

Excessive dosages of Mod GRF 1-29 may also lead to tingling or numbness in the hands and feet. Water retention can be another sign that the dosage is too high and should be reduced. As always, it is recommended to discontinue use and call a physician immediately if any negative side effects are suspected.