AAKG (Arginine Alpha-Ketoglutarate)

What AAKG is

AAKG combines L-arginine with alpha-ketoglutarate, an intermediate of the citric acid cycle that is also sold as Ca-AKG. 1,000 mg of AAKG contain around 544 mg of arginine and 450 mg of alpha-ketoglutarate (VKM 2016). Per gram, AAKG therefore delivers only just over half as much arginine as pure arginine.

In the BK-Score, AAKG stands at 3 out of 10 points for human evidence. For arginine itself the data are considerably broader, for example on blood pressure; these results, however, cannot simply be transferred to AAKG, and certainly not to the “pump” during training.

How it is supposed to work

Arginine is the substrate of NO synthase, which produces nitric oxide, and nitric oxide dilates blood vessels. From this the advertising derives: more arginine, more nitric oxide, more blood flow in the muscle, better nutrient supply and more performance.

The first step has been shown in humans: arginine levels in the blood rise. The following steps have not: in the only study that measured blood flow and nitric oxide breakdown products after training, neither rose more with AAKG than with placebo.

What the studies show

Blood flow: no difference from placebo

Willoughby 2011 gave 24 physically active men 12 g of AAKG per day or placebo for 7 days. Afterwards, heart rate, blood pressure, blood flow in the brachial artery and nitric oxide breakdown products after an arm workout rose equally in both groups. Only plasma arginine was higher under AAKG. The authors attribute the changes to the training alone.

Acute strength performance: no effect

Wax 2012 tested 8 trained and 8 untrained men in a double-blind crossover design: 3 g of AAKG or placebo, 45 minutes before training. Maximal strength and repetitions to exhaustion in the bench press and leg press did not differ, regardless of training status.

Eight weeks of strength training: isolated positive values

Campbell 2006 assigned 35 trained men to 12 g of AAKG per day or placebo over 8 weeks of strength training. The authors report significant improvements in the AAKG group in the bench press and in peak power in the Wingate test, as well as changes in blood glucose and plasma arginine. Body composition, body water, leg muscle endurance and aerobic capacity did not differ between the groups. Confirmation by a second study of this length is lacking.

Case reports from the emergency department

Prosser 2009 described three young men who came to the emergency department with racing heart, dizziness, vomiting and near-fainting after taking AAKG-containing products; two were admitted for observation. ECG and laboratory values were unremarkable. The authors consider vasodilation possible; other causes could not be ruled out.

Where the data stop

• The “pump”. More blood flow in the muscle is the central advertising promise, and in the only study on this there was no difference from placebo (Willoughby 2011).
• Combination products. Many boosters contain AAKG together with creatine and other substances. In one such study the mixture increased peak power; what share AAKG had in this cannot be said (Little 2008).
• Women, older people, long-term use. The studies were conducted almost exclusively in men and over 8 weeks at most.
• Safe amounts. In 2016 the Norwegian food safety authority VKM was unable to assess any amount of AAKG in food supplements due to a lack of data.

Status, approval and legal

In Germany, AAKG is offered as an ingredient in food supplements and pre-workout boosters. There is no official maximum amount from EFSA or BfR for either AAKG or arginine. In 2016 the Norwegian food safety authority VKM found 1,000 to 2,000 mg of AAKG per day in food supplements and was unable to assess any of these amounts because the studies on AAKG are too sparse. Health claims on blood flow or performance are not authorized for AAKG in the EU. Arginine is not on the World Anti-Doping Agency’s prohibited list.

Safety

In the controlled studies in healthy men over up to 8 weeks, no serious side effects occurred. Alongside these are three case reports with racing heart and dizziness after AAKG-containing products, in which the connection remains open. Because AAKG delivers arginine, the notes on L-arginine also apply: it can enhance the effect of blood pressure–lowering drugs, and after an acute heart attack arginine is not indicated. In the BK-Score, the safety data stand at 3 out of 10. This text is information and does not replace medical advice.

Sources

• Campbell B et al., Nutrition 2006 – pharmacokinetics, safety and performance, 8 weeks, 35 trained men (PMID 16928472)
• Willoughby DS et al., Int J Sport Nutr Exerc Metab 2011 – 7 days of AAKG, blood flow and nitric oxide (PMID 21813912)
• Wax B et al., J Int Soc Sports Nutr 2012 – acute AAKG intake, strength in trained and untrained men (PMID 22510253)
• Little JP et al., Int J Sport Nutr Exerc Metab 2008 – creatine with AAKG and other ingredients (PMID 19033611)
• Prosser JM et al., Hum Exp Toxicol 2009 – case reports on AAKG-containing products (PMID 19755457)
• VKM 2016 – risk assessment of L-arginine and arginine alpha-ketoglutarate in food supplements (Norway)