Creatine increases muscle mass, but not strength, in HIV-positive men

Creatine, a supplement frequently promoted for building muscle mass, can increases lean body mass in HIV-positive men, but does not increase strength when used with resistance exercise (weight training), US and Greek researchers reported on Monday at the Seventh International Workshop on Adverse Drug Reactions and Lipodystrophy in HIV, in Dublin, Ireland. Furthermore the increase in body mass is likely to be caused by fluid retention and is highly unlikely to produce any long-term survival benefit.

Despite the success of antiretroviral therapy in prolonging life and controlling HIV infection, people with HIV still continue to experience loss of lean body mass whether they are receiving treatment or not.

An American study involving over 500 antiretroviral-treated individuals established that a loss of just 3% of body weight from baseline was predictive of a poorer prognosis. What's more, a recent study found that over 50% of patients starting HIV therapy experienced a fall in their weight and that the risk of the loss of 5% or more of body weight has actually increased since effective anti-HIV therapy became available. Poverty, a low baseline CD4 cell count, and/or high viral load and opportunistic infections have all been identified as risk factors for unintended weight loss in patients taking HIV therapy.

Thus, therapies or interventions which can maintain and increase body mass are of critical importance to people with HIV, but many treatments currently in use are untested and their use is driven by anecdotal evidence.

Creatine has been promoted to athletes and body builders as a supplement that can provide extra energy to muscles, so building greater endurance and greater strength. It also draws water into muscle fibres, increasing their volume, and may enhance protein synthesis, leading to growth of muscle tissue.

The supplement is widely available, but its use is controversial in sports circles; many regard its use as a means of bulking muscles with water, and see little convincing evidence that it improves performance except in activities that require a short burst of energy.

Researchers at the University of California, San Francisco, conducted a randomised placebo-controlled study of creatine supplementation in a group of 40 HIV-positive men who underwent a 14 week course of supervised resistance exercise, three times a week. Participants received creatine or placebo for two weeks before beginning resistance exercise.

Creatine was dosed at 20mg a day for the first five days in order to `load` the muscle tissue with creatine, and thereafter dosed at 4.8g a day for six weeks. The cycle of loading and maintenance was then repeated.

Strength was assessed by measuring the 1 repetition maximum for eight different muscles (the 1RpM is the maximum amount of weight that can be lifted in a particular exercise, and resistance exercises generally aim to use weights that are 70-75% of the 1RpM for a particular exercise).

Men in the creatine group gained approximately 2.3kg in lean body mass compared with 0.9kg in the exercise only group, and this difference was statistically significant (p=0.01) but there was no difference in strength as assessed by 1RpM at the end of the study. In both groups strength increased by approximately 40%. No difference in metabolites could be detected in muscle tissue between the creatine group and placebo group.

“Creatine was increasing muscle mass by fluid retention in the muscle and there is no evidence that this sort of change will have any long-term benefit for survival in people with HIV”, Giorgo Sakkas of the University of Thessaly, principal investigator on the study, told aidsmap.

“Creatine is not a long-term solution to improving lean body mass in people with HIV, and the lean body mass increase required in order to improve survival is a long-term increase that can only be achieved through improved dietary intake of protein and consistent resistance exercise.”

He speculated that the lack of improvement in strength in the creatine group may be due to inefficient use of the energy generated by creatine as a result of mitochondrial damage, but the numbers involved in the study were too small to compare the characteristics of responders and non-responders.

People with HIV also need to be aware of the risk of long-term toxicity with creatine supplementation, Giorgo Sakkas told aidsmap. Apart from causing muscle pain and cramping in the shorter term, creatine may also cause kidney damage with longer term use, especially if the dose is too high or the user is suffering from renal insufficiency. There may be a particular risk in those patients taking tenofovir or other drugs associated with raised creatine levels.