Our energy levels are directly related to the health of our digestion system. An efficient digestion system helps to keep our energy levels soaring, as we easily metabolize and utilize nutrients, which give us energy, from our food. Digestion itself requires your body to work and expend energy. So if your digestion is sluggish, you too can feel sluggish and low in energy. One reason for poor digestion is a lack of sufficient acidity within the stomach. Drinking vinegar is an acidic food, helping to increase stomach acidity and improve digestion. Drinking vinegar also contains B-vitamins, which are essential for energy, digestion and optimal metabolism. A common recommendation is to drink drinking vinegar prior to meal to improve digestion, which in turn helps to improve energy levels.
References: "Textbook of Nutritional Medicine"; "Melvyn Werbach et al.; 1999, "Superfoods: The Healthiest Foods on the Planet"; Tonia Reinhard; 2010, "Encyclopedia of Natural Medicine"; M. Murray et al.; 2008, "Advanced Nutrition and Human Metabolism"; Sareen Gropper et al.; 2009