Taking supplements of creatine, a compound found in muscle tissue, can significantly boost both working memory and general intelligence, according to researchers in Australia.
The work, to be published in the Proceedings B journal published by the UK's Royal Society, found that young adult vegetarians who took 5g of creatine had better recall under pressure than the control group.
"The level of creatine supplementation chosen was 5g per day as this is a level that has previously been shown to increase brain creatine levels. This level is comparable to that taken to boost sports fitness," explained Dr Caroline Rae from the University of Sydney.
"Vegetarians or vegans were chosen as carnivores and omnivores obtain a variable level of creatine depending on the amount and type of meat they eat - although to reach the level of supplementation in this experiment would involve eating around 2kg of meat a day!" she added.
Creatine supplements are widely used by athletes and fitness fanatics to increase sports performance. It is manufactured by the body, but also found in dietary sources such as meat. A close relative of the amino acids, it has also been trialed successfully in the treatment of neurological, neuromuscular and atherosclerotic disease.
"We know that creatine plays a pivotal role in maintaining energy levels in the brain," said Dr Rae. "It was a reasonable hypothesis that supplementing a diet with creatine could assist brain function."
The experiment tested this hypothesis by giving a group of 45 subjects a creatine supplement and a second group a placebo for six weeks, followed by a six week period with no intake and a final six week period when the control and placebo group were swapped. Intelligence and memory were tested at four points: the start of the trial; the end of the first six week period; and the start and endpoint of the final six week period.
The effect on working memory was tested using a backward digit span test in which the subject has to repeat in reverse order progressively longer verbal random number sequences. Intelligence was tested using Ravens Advanced Progressive Matrices - a methodology commonly used for IQ assessment involving completion of pattern sequences. The test is a well validated measure of general ability with minimal dependence on cultural factors.
"Both of these tests require fast brain power and the Ravens task was conducted under time pressure," said Dr Rae. "The results were clear with both our experimental groups and in both test scenarios: creatine supplementation gave a significant measurable boost to brain power. For example in the digit span test, subjects' ability to remember long numbers, like telephone numbers, improved from a number length of about 7 to an average of 8.5 digits."
The study shows that increased creatine intake results in improved brain function, similar to effects shown previously in muscle and heart. The results also appear to back previous observations showing that brain creatine levels correlate with improved recognition memory and reduced mental fatigue.
"These findings underline a dynamic and significant role of brain energy capacity in influencing brain performance," said Dr Rae. "Increasing the energy available for computation increases the power of the brain and this is reflected directly in improved general ability."
Long-term supplementation with creatine has yet to be declared fully safe as there have been reported effects on glucose homeostasis (the regulation of blood sugar levels) and potential subjects with a medical history of diabetes were excluded from the experiment. In addition taking the supplement can have some antisocial effects, "[it] can make you a considerably less 'fragrant' person", according to Dr Rae.
But she added that creatine supplementation may be of use to those requiring boosted mental performance in the short-term, such as university students.