The first article of a four-part series on nutritional interventions examines evidence on the use, safety and efficacy of low-carbohydrate dieting for weight loss and intractable epilespy.
DR. BRAGANZA is an assistant professor of pediatrics at Children's Hospital at Montefiore Albert Einstein College of Medicine, Bronx, NY.
DR. OZUAH is a professor of pediatrics and interim university chairman at Children's Hospital at Montefiore Albert Einstein College of Medicine, Bronx, NY.
The authors have nothing to disclose in regard to affiliations with, or financial interests in, any organization that may have an interest in any part of this article.
The first description of a low-carbohydrate diet was by a 19th century British carpenter, William Banting, who, in 1863, described a diet high in protein and fat and low in carbohydrates that he claimed helped him to lose 46 pounds in one year.13 Popular interest in the low-carbohydrate approach was renewed by Robert Atkins in 1973 and has since waxed and waned. In recent years, additional diets, such as South Beach, Sugar Busters, and Zone, contributed to a sustained interest in weight loss through low-carbohydrate eating.
During the first two weeks of the Atkins diet, unlimited amounts of meat, poultry, seafood, eggs, cheese, oil, and butter are allowed while carbohydrate intake is limited to no more than 20 g/day, obtained mainly through salad greens and vegetables.14 The diet prohibits milk, fruit, grains, cereal, and bread as well as vegetables that have a high glycemic index (carrots, peas, corn). It also calls for multivitamin and potassium citrate supplementation and plenty of water.14 During the first few days of the diet, water loss causes a shift in pH and a slight reduction in electrolyte levels, which return to baseline within four weeks. After these initial two weeks, 5 additional grams of carbohydrate are added weekly to the diet, to a maximum of 40 to 90 g/day.
Professional organizations have cited concerns about serious adverse outcomes using the low-carbohydrate diet-particularly for adults with cardiovascular disease, type 2 diabetes, dyslipidemia, and hypertension. Specific concerns include the abnormal metabolism of insulin and impaired liver and kidney function secondary to accumulation of ketones; excessive consumption of fats resulting in hyperlipidemia; excessive consumption of protein causing impaired renal function; and bone mineral loss. Furthermore, a low-carbohydrate diet is low in vitamins E, A, thiamine, and folate and in calcium, magnesium, and zinc, whereas a low-fat diet is typically deficient in vitamin B2.16 These micronutrient deficiencies are a particular concern in adolescents, whose diets tend to vary and so may already be deficient in these essential nutrients that are required for optimal growth and development.