Esophageal injury by apple cider vinegar tablets and subsequent evaluation of products

Nutrition Research Newsletter, August, 2005

Apple cider vinegar products are advertised in the popular press and over the Internet for treatment of a variety of conditions, including aging, weight loss, hemorrhoids, high blood pressure, arthritis, sore throat, and indigestion. A 48 year old woman reported an adverse event to the authors. She developed severe pain and difficulty swallowing, after an apple cider vinegar tablet became lodged in her throat for approximately 30 minutes. A review of the medical record revealed possible injury, with tenderness of the larynx and pain during swallowing and neck palpation. An esophagogastroduodenoscopy performed 14 days later appeared normal; however, 6 months after the initial event, the patient reported continued pain and difficulty swallowing. Subsequently, apple cider vinegar products were gathered and evaluated for pH and for component acids (acetic, citric, malic, and lactic) using high-performance liquid chromatography (HPLC). After noticing potential microbial growth in samples prepared at room temperature, bacterial--aerobic plate counts--and yeast/mold counts were conducted.

Considerable variability was found between brands. The pH readings for all samples were acidic and ranged from 2.9 to 5.7. Acetic acid in the samples ranged from 1.04% to 10.57%. Citric acid ranged from 0% to 18.5%. None of the samples contained lactic acid. Malic acid was present in sample G only (49.12%). Average weight per tablet ranged from 380 mg to 758 mg. Dosage recommendations varied tremendously from one tablet (300 mg) daily to two tablets (500 mg) three times daily.

Product labels did not appear to be accurate regarding the amount of acetic acid present. Sample C claimed to contain 4% acetic acid and was determined to contain 2.22%. Sample D claimed to contain a minimum of 35% acetic acid, but was found to contain only 3.2%, with the majority of the acid present as citric--18.54%. Sample G also claimed to have a minimum of 35% acetic acid, but only contained 2% with the predominant acid being malice--49.12%.

If samples D and G had, in fact, contained the amount of acid claimed on the label, they could be considered poisonous, as indicated by the Consumer Product Safety Commission, which states that an "acetic acid preparation containing free or chemically unneutralized acetic acid in concentration of 20% or more shall be deemed a poison." Apple cider vinegar tablets could also be considered toxic according to the Code of Federal Regulations because personal injury occurred when swallowed. Under these guidelines, apple cider vinegar tablets could possibly be considered a corrosive agent due to their ability to destroy living tissues.

Severity of acid chemical burns can be attributed to length of contact time, pH, volume, concentration, and physical form of the acid. Despite the fact that the esophagus is described as relatively unaffected by acid ingestion, the concentration of acid in sample H in conjunction with the contact time was sufficient to cause injury, in the case described here. Five of the samples contained component acid concentrations 3 times to 10 times the amount found in household vinegar, which is typically 5% acid. Two samples had greater component acid content and were more acidic than the brand (sample H) ingested by the woman described here. Product G had the highest component acid content and was one of the largest tablets; therefore, of all the samples tested, it could present the greatest risk of injury.

No bacterial growth was detected on aerobic count plates. Samples A, B, and E had yeast and mold counts in the range of 103 to 105 colony-forming units/g. Sample E claimed to be yeast-free, but tested positive for yeast and mold contamination--yet another label inaccuracy discovered in the testing of these products. However, samples D and H also claimed to be yeast-free and this proved to be accurate.

Some of the labels imply that taking this product will aid in weight control or loss, and it is unclear if these claims are within the allowed structure/function claims for dietary supplements. Also, sample F, which was obtained on the Internet, claimed to be "a blood thinner, detoxifier, and/or diuretic," have "cleansing, healing, and germ fighting abilities," and to aid in "weight loss, digestive difficulties, joint pain and infections." This product appeared to be promoted as a drug according to the Federal Food Drug and Cosmetic Act.

Dietetics professionals should continue to be vigilant in eliciting information from their clients about their dietary supplement use. In addition, clients should be encouraged to inform their physicians of all supplements in use. Dietetics professionals are in a unique position to provide science-based, credible information to their clients, especially those at high risk, who may have greater potential for herb-drug interactions. The risks associated with these products often may be greater than any possible benefit. The inconsistency and inaccuracy in labeling, variability in dosage recommendations, and unsubstantiated health claims cause suspicion about the safety and quality of these particular products.