The assessor’s Panel on Dietetic Products, Nutrition and Allergies (NDA) found Unicer Bebidas de Portugal SGPS’s claim did not demonstrate causality between drinking its mineral water, Melgaço, and reduced rates of glycaemia in glycaemic individuals.

It is the first claim the NDA has assessed in the area of hyperglycaemia, which the Portuguese company linked to a condition called type 2 diabetes mellitus in its dossier. But the NDA said the disease for which hyperglycaemia is a risk factor was not clearly specified.

The NDA highlighted several issues with the Portuguese company’s presented science of one human intervention study and two animal studies.

The human intervention study featured 100 subjects at a Melgaco spa with pathologies of the upper respiratory tract, of the osteo-articular system, or type 2 diabetes mellitus. Subjects who were hyperglycaemic but not diabetic were not specified.

No significant changes

When all subjects were considered together, fasting plasma glucose (FPG) levels significantly decreased after the 14-day intervention and significantly increased during the 9-month follow-up.

“FPG in these subjects significantly decreased after the 14-day intervention. No significant changes were observed in fasting plasma insulin or glycated haemoglobin during this period, or in FPG, fasting plasma insulin or glycated haemoglobin at the end of the 9-month follow-up as compared to the end of the intervention,” NDA said.

The trial was compromised by the undefined nature of the treatment (including the frequency and amount of Melgaço mineral water consumption), background diet and medication.

“The Panel considers that the significant weaknesses of this study greatly limit its value as a source of data to support the claimed effect.”

One of the animal studies was considered to have inconclusive data regarding the number of animals per group, statistical analyses used and quantitative results.

The other animal study looked at the effects of the Melgaço mineral water on glucose homeostasis, insulin secretion, and insulin resistance in diabetic Goto-Kakizaki rats (a model of type 2 diabetes) and in normal (non-diabetic) Wistar rats.

“The Panel considers that the significant weaknesses of this animal study (lack of adequate controls, no data available regarding the baseline characteristics of the animals nor on the changes observed in the intervention and control groups during the study) and the fact that results obtained in this experimental animal model cannot be extrapolated with any confidence to human subjects with hyperglycaemia greatly limit its value as a source of data to support the claimed effect.”

It therefore concluded causality had not been demonstrated.