Scientific Opinion on the substantiation of health claims related to
alpha-lipoic acid and “protection of the nerve system” (ID 3157) and
increase in insulin sensitivity (ID 3158) pursuant to Article 13(1) of
Regulation (EC) No 1924/2006[sup]1[/sup]
EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA)2, 3
European Food Safety Authority (EFSA), Parma, Italy
Słowa kluczowe:
alpha-lipoic acid
health claims
insulin sensitivity
nervous system
1. Charakterystyka żywności / składnika
The food constituent that is the subject of the health claims is alpha-lipoic acid.
alpha-Lipoic acid, also known as thioctic acid, is a non-essential sulphur-containing food constituent, present in foods, generally bound to protein (lipoyllysine), at very low concentrations (around 0.3 mg/100 g for the richest natural sources, i.e. spinach for vegetables and kidney for meat). The natural compound is the R enantiomer, while in food supplements generally the racemic form (R/S) is used. It exists in redox forms, the oxidised form with a ring containing a disulfide bond or a reduced form, in which the ring has been opened forming two thiol groups (dihydrolipoic acid). Alpha-lipoic acid is measurable in foods by established methods.
The Panel considers that the food constituent, alpha-lipoic acid, which is the subject of the health claims, is sufficiently characterised.
2. Znaczenie oświadczenia dla zdrowia człowieka
2.1. Ochrona układu nerwowego (ID 3157)
The claimed effect is “protection of nerve system”. The Panel assumes that the target population is the general population.
From the references provided, which reported on the treatment of neurological complications of diabetes (i.e. diabetic polyneuropathy), the Panel considers that the claim is related to the treatment of a disease, and does not comply with the criteria laid down in Regulation (EC) No 1924/2006.
The Panel notes that the clarifications provided by Member States mention lipid peroxidation. A claim on alpha-lipoic acid and protection of body lipids from oxidative damage has already been assessed with an unfavourable outcome (EFSA Panel on Dietetic Products Nutrition and Allergies (NDA), 2010). The references cited for the present claim did not provide any additional scientific data which could be used to substantiate the claim.
2.2. Zwiększenie wrażliwości na insulinę (ID 3158)
The claimed effect is “glucose metabolism”. The Panel assumes that the target population is the general population.
From the references provided, the Panel assumes that the claimed effect refers to an increase in insulin sensitivity.
The Panel considers that an increase in insulin sensitivity is a beneficial physiological effect.
3. Naukowe uzasadnienia wpływu na zdrowie człowieka -
3.1. Zwiększenie wrażliwości na insulinę (ID 3158)
The references provided to substantiate the claim included one narrative review on alpha-lipoic acid on various health outcomes, which did not provide any original data that could be used to substantiate the claim. The Panel considers that no conclusions can be drawn from this reference for the scientific substantiation of the claim.
One reference reported on a human intervention study which addressed the effects of alpha-lipoic acid administered intravenously on insulin-mediated glucose disposal in patients with type 2 diabetes (Jacob et al., 1995). The Panel notes that the intravenous route of administration is not relevant for human nutrition, and considers that no conclusions can be drawn from this study for the scientific substantiation of the claim.
Another reference (Kamenova, 2006) reported on an open-label, case-control study which assessed the effect of oral administration of alpha-lipoic acid on insulin sensitivity in patients with type 2 diabetes (n=12) treated with metformin tablets. The Panel notes that metformin is known to increase insulin sensitivity in type 2 diabetic subjects, and considers that the evidence provided does not establish that type 2 diabetic subjects under pharmacological treatment with metformin are representative of the target population for which the claim is intended. The Panel considers that no conclusions can be drawn from this study for the scientific substantiation of the claim.
Konrad et al. (1999) studied the effect of alpha-lipoic acid administered orally (600 mg, twice daily) for four weeks on blood insulin and glucose concentrations using an oral glucose tolerance test (OGTT) and a modified frequently sampled intravenous glucose tolerance test (FSIGTT) in lean (n=10) and obese (n=10) male patients with type 2 diabetes. The Panel notes that this study is an uncontrolled, open-label intervention, and considers that no conclusions can be drawn from this study for the scientific substantiation of the claim.
The Panel concludes that a cause and effect relationship has not been established between the consumption of alpha-lipoic acid and an increase in insulin sensitivity.
Wnioski
On the basis of the data presented, the Panel concludes that:
The food constituent, alpha-lipoic acid, which is the subject of the health claim, is sufficiently characterised.
“Protection of nerve system” (ID 3157)
The claimed effect is “protection of nerve system”. The target population is assumed to be the general population.
The claim is related to the treatment of a disease, and does not comply with the criteria laid down in Regulation (EC) No 1924/2006.
A claim on alpha-lipoic acid and protection of body lipids from oxidative damage has already been assessed with an unfavourable outcome. The references cited for the present claim did not provide any additional scientific data which could be used to substantiate the claim.
Increase in insulin sensitivity (ID 3158)
The claimed effect is “glucose metabolism”. The target population is assumed to be the general population. From the references provided, it is assumed that the claimed effect refers to an increase in insulin sensitivity. An increase in insulin sensitivity is a beneficial physiological effect.
A cause and effect relationship has not been established between the consumption of alpha-lipoic acid and an increase in insulin sensitivity.
