Alpha-keto-isovalerate as a biomarker of prebiotic efficacy for weight gain prevention

1. A method for predicting and/or quantifying the response of a subject to prebiotics in the prevention of diet induced weight gain, comprising:

a) determining a level of alpha-keto-isovalerate in a urine sample obtained from a subject that has consumed prebiotics using 1 H-NMR spectroscopy or mass spectroscopy, and

b) comparing the subject's alpha-keto-isovalerate level to a predetermined reference value by mapping or graphing the urinary excretion of alpha-keto-isovalerate, wherein a decreased alpha-keto-isovalerate level, or an absence of change in the alpha-keto-isovalerate level, in the urine sample compared to the predetermined reference value indicates that the administration of prebiotics is effective in the prevention of diet induced weight gain in the subject,

and wherein the predetermined reference value is based on an average alpha-keto-isovalerate level in a control population of subjects consuming a high fat diet and the change of alpha-keto-isovalerate level is determined relative to a cut-off value.

2. The method of claim 1 , wherein the diet is a high fat diet.

3. The method of claim 1 , further comprising the steps of

a) determining the level of at least one further biomarker selected from the group consisting of oxaloacetate, creatinine, trimethylamine, and indoxyl sulfate in the urine sample, and

b) comparing the subject's level of the at least one further biomarker to a predetermined reference value,

wherein:

(i) a decreased oxaloacetate, creatinine, and/or indoxyl sulfate level, or an absence of change in the oxaloacetate, creatinine, and/or indoxyl sulfate level, in the urine sample; and/or

(ii) an increased trimethylamine level, or an absence of change in the trimethylamine level, in the urine sample;

compared to the predetermined reference values indicates that the administration of prebiotics will be effective in the prevention of diet induced weight gain in the subject.

4. The method according to claim 1 , wherein the predetermined reference value is the alpha-keto-isovalerate level in urine in the subject before the prebiotics were consumed.

5. The method according to claim 1 , wherein the level of alpha-keto-isovalerate and/or the further biomarkers are determined in a urine sample obtained from the subject after at least three consecutive days of prebiotic consumption.

6. The method according to claim 1 , wherein the prebiotic is selected from the group consisting of oligosaccharides, optionally containing fructose, galactose, mannose; dietary fibers, in particular soluble fibers, soy fibers; inulin; or mixtures thereof.

7. The method according to claim 6 , wherein the prebiotics are selected from the group consisting of fructo-oligosaccharides (FOS); galacto-oligosaccharides (GOS); isomalto-oligosaccharides; xylo-oligosaccharides; bovine milk oligosaccharides (BMOS); glycosylsucrose (GS); lactosucrose (LS); lactulose (LA); palatinose-oligosaccharides (PAO); malto-oligosaccharides (MOS); gums and/or hydrolysates thereof; pectins and/or hydrolysates thereof; and combinations thereof.

8. The method of claim 7 , wherein the prebiotics comprise (a) galactooligosaccharides (GOS) (b) bovine milk oligosaccharides (BMOS) or (c) inulin and fructooligosaccharides (FOS).

9. The method of claim 8 , wherein the bovine milk oligosaccharides (BMOS) comprise cow's milk oligosaccharides-galactooligosaccharides (CMOS-GOS).

10. The method according to claim 1 , wherein the subject has consumed the prebiotics in an amount of at least 2 g/day.

11. The method according to claim 1 , wherein the subject is a mammal such as a human; a non-human species, including a primate; a livestock animal such as a sheep, a cow, a pig, a horse, a donkey, or a goat; a laboratory test animals such as mice, rats, rabbits, guinea pigs, or hamsters; or a companion animal such as a dog or a cat.

12. The method according to claim 1 , wherein the method is used to devise a stratified diet for a group of subjects or a personalized diet for the subject.

13. A method for preventing diet-induced weight gain in a subject, comprising:

a) performing a method as described in claim 1 ; and

b) administering prebiotics to the subject if the level of alpha-keto-isovalerate in the urine sample is decreased or unchanged compared to the predetermined reference value.

14. A method according to claim 13 , wherein administration of prebiotics to the subject is continued for at least one month.

15. A method according to claim 13 , wherein if the level of alpha-keto-isovalerate in the urine sample is increased compared to the predetermined reference sample, prebiotics are not administered to the subject.

16. A method according to claim 15 , wherein an alternative treatment for weight gain prevention is provided to the subject, the treatment selected from calorie restriction, dietary fat intake reduction, a non-prebiotic weight loss product, or an exercise program.