Following a request from the European Commission, the Panel on Dietetic Products, Nutrition and Allergies was asked to provide a scientific opinion on a list of health claims pursuant to Article 13 of Regulation (EC) No 1924/2006. This opinion addresses the scientific substantiation of health claims in relation to beta-hydroxy beta-methylbutyrate monohydrate (HMB) alone or in combination with alpha-ketoisocaproic acid (KIC) and reduction of muscle tissue damage during exercise, increase in lean body mass, increase in muscle strength, increase in endurance performance, skeletal muscle tissue repair and faster recovery from muscle fatigue after exercise. The scientific substantiation is based on the information provided by the Member States in the consolidated list of Article 13 health claims and references that EFSA has received from Member States or directly from stakeholders. The food constituent that is the subject of the health claims is HMB, either alone or in combination with KIC. The Panel considers that HMB either alone or in combination with KIC is sufficiently characterised. Reduction of muscle tissue damage during exercise The claimed effects are "minimize muscle protein breakdown" and "HMB and exercise induced muscle breakdown". The target population is assumed to be adults performing resistance exercise. In the context of the proposed wordings and the references provided, the Panel assumes that the claimed effects relate to the reduction of damage to muscle tissue during exercise. The Panel considers that reduction of muscle tissue damage during exercise is a beneficial physiological effect. In weighing the evidence, the Panel took into account that although one small randomised controlled trial with methodological limitations reported a significant effect of HMB in combination with KIC on surrogate measures of muscle damage during resistance training, one meta-analysis of randomised controlled trials, which included five studies and eight intervention arms, did not show an effect of HMB supplementation on muscle tissue damage during exercise. On the basis of the data presented, the Panel concludes that a cause and effect relationship has not been established between the consumption of HMB, either alone or in combination with KIC, and reduction of muscle tissue damage during exercise. Increase in lean body mass The claimed effects are "increasing mass", "HMB and lean body mass", and "HMB and training adaptations". The target population is assumed to be physically active individuals in the general population. In the context of the proposed wordings, the Panel assumes that the claimed effects refer to an increase in lean body mass relative to body fat mass. The Panel considers that an increase in lean body mass is a beneficial physiological effect. In weighing the evidence, the Panel took into account that a meta-analysis of ten randomised controlled trials, and one additional randomised controlled trial not included in the meta-analysis, did not show a significant effect of HMB consumption on lean body mass during training compared to placebo. On the basis of the data presented, the Panel concludes that a cause and effect relationship has not been established between the consumption of HMB, either alone or in combination with KIC, and increase in lean body mass. Increase in muscle strength The claimed effects are "increasing strength", "HMB and training adaptations", and "HMB and changes in muscle strength during training". The target population is assumed to be adults performing resistance training to improve muscle strength. In the context of the proposed wordings, the Panel assumes that the claimed effects refer to an increase in muscle strength. The Panel considers that an increase in muscle strength is a beneficial physiological effect. In weighing the evidence, the Panel took into account that the results from a meta-analysis of randomised controlled trials with respect to the effect of HMB consumption on muscle strength are inconsistent, that no significant effect of HMB consumption on muscle strength was shown in the target population for the claim, and that no evidence for a mechanism by which HMB could exert the claimed effect was provided. On the basis of the data presented, the Panel concludes that a cause and effect relationship has not been established between the consumption of HMB, either alone or in combination with KIC, and increase in muscle strength. Increase in endurance performance The claimed effects are "increasing exercise lactate threshold and VO2 peak", and "HMB and aerobic metabolism". The target population is assumed to be adults performing endurance exercise. In the context of the proposed wordings and clarifications provided by Member States, the Panel assumes that the claimed effects refer to an increase in endurance performance. The Panel considers that increase in endurance performance is a beneficial physiological effect. No references which addressed the effects of HMB supplementation in humans on measures of endurance performance, and from which conclusions could be drawn for the scientific substantiation of the claim, were provided. On the basis of the data presented, the Panel concludes that a cause and effect relationship has not been established between the consumption of HMB, either alone or in combination with KIC, and increase in endurance performance. Skeletal muscle tissue repair The claimed effect is "HMB and normal muscle repair". The target population is assumed to be adults performing resistance exercise. In the context of the proposed wordings, the Panel assumes that the claimed effect refers to the rebuilding of structural protein within skeletal muscle tissue after exercise which has caused muscle damage. The Panel considers that skeletal muscle tissue repair is a beneficial physiological effect. No references which addressed the effects of HMB supplementation in humans on measures of skeletal muscle tissue repair were provided. On the basis of the data presented, the Panel concludes that a cause and effect relationship has not been established between the consumption of HMB, either alone or in combination with KIC, and skeletal muscle tissue repair. Faster recovery from muscle fatigue after exercise The claimed effects are "sport exercise recovery" and "HMB and muscle recovery after training". The target population is assumed to be adults performing strenuous exercise. The Panel assumes that the claimed effects refer to muscle fatigue recovery after exercise. The Panel considers that faster recovery from muscle fatigue after exercise is a beneficial physiological effect. In weighing the evidence, the Panel took into account that the one human intervention study provided from which conclusions could be drawn for the scientific substantiation of the claim did not show an effect of HMB on faster recovery from muscle fatigue after exercise. On the basis of the data presented, the Panel concludes that a cause and effect relationship has not been established between the consumption of HMB, either alone or in combination with KIC, and faster recovery from muscle fatigue after exercise.
