A recent paper1 reports beneficial health effects of consumption of acetic acid (main component, after water, of vinegar*) by mice. The authors report earlier studies by their group that showed reduction of hyperglycemia in diabetic mice,2 reduction of serum cholesterol and triacylglycerols (triglycerides) in rats fed a cholesterol-rich diet3 and antihypertensive effects of acetic acid and vinegar on spontaneously hypertensive rats.4In their new paper,1 they studied the effect of acetic acid on the accumulation of body fat and liver lipids.
* Typical commercial vinegar contains about 5% acetic acid.
The high-fat diet-induced obese mice were intragastrically administered with water or 0.3 or 1.5% acetic acid for 6 weeks. (Not too much fun for the mice, but perhaps less awful than drinking vinegar. Important for the experimental analysis, though, because the researchers could be sure of exactly how much of the stuff each mouse consumed.) By the end of the study, the incremental ratios of body weight gain were 37.3% for the control group, 29.5% for the low-dose acetic acid group, and 27.7% for the high-dose acetic acid group. Tissue weight/body weight ratios of liver, total white adipose tissue, and mesenteric white adipose tissue in both the high and low-dose groups were significantly lower as compared to the control group. There was no significant difference in the gastrocnemius muscle weight between the three groups.
The researchers determined that “the main mechanism by which AcOH [acetic acid] intake suppressed body fat accumulation in this study is suggested to be upregulation of fatty acid oxidation ... .”1 They analyzed for SREBP-1, an enzyme that regulates gene expression of lipogenic (fat manufacturing) enzymes and PPARalpha, a gene that regulates fatty acid oxidation, in the liver, where (the authors explain) almost all acetate in the portal circulation is metabolized. They also looked at possible changes in other lipogenic enzymes, including FAS (fatty acid synthase) and ACC; however, they found no changes in these.
What the researchers found was that PPARalpha gene expression in both the high and low-dose groups was significantly upregulated. Uncoupling protein 2 (UCP2), which plays a role in thermogenesis (metabolizing fats to produce heat) was also elevated.
Thus, the Old Wives’ Tale about the weight-reducing effect of vinegar was true in the case of mice and probably would work similarly in humans. (Vinegar has been found in human studies to improve insulin sensitivity to a high-carbohydrate meal in subjects with insulin resistance or type 2 diabetes2 as well as in healthy subjects.3) The moral of this story is that just because something is an Old Wives’ Tale doesn’t prove that it isn’t true but until you have some experimental measurements, you certainly shouldn’t count on it being true. A reasonable dose would be 1 to 2 tablespoons of vinegar per day diluted with about ten times as much water before swallowing, taken with meals.
Also, see our earlier article “Effects of acetic acid (vinegar) on glycemic and insulinemic response to food: inhibitory effects on digestive and other enzymes” published in Vol. 9 No. 2 (April 2006) of this newsletter.