What are the side effects?
The most common, almost “expected”, side effects of the diet are constipation, acidosis (especially with illness), and decreased weight gain (not often weight loss). These are often addressed immediately when the diet is started, especially using Miralax™ for constipation. The less common side effects, generally occurring in 1 in 20 children, include high cholesterol, kidney stones, growth slowing, and gastrointestinal upset.
In 2001, Peter Kwiterovich, MD, reported in JAMA our experience at Johns Hopkins Hospital in regards to cholesterol of children on the diet.(2) In general, most children have a 30% increase in total cholesterol, LDL cholesterol, and triglycerides. Fortunately, this increase happens within 3 months but usually doesn’t continue to increase (and in studies of children on the diet for over 6 years, may return to normal). Although we often recommend adding MCT oil (link to Keto News article), increasing the percentage of polyunsaturated fatty acids, and lowering the ketogenic diet ratio, these interventions have been looked at in only small numbers of patients. Many families are worried about the long-term effects of high cholesterol, but we suspect that the short periods of time that most children are on the diet do not impact later atherosclerosis.
Around the same time, in 2000, Susan Furth, MD, showed both that there is a 5% chance of kidney stones in children on the diet and that it was more likely to occur in those who had high amounts of calcium in their urine.(3) She suggested that using Polycitra K™ to make the urine less acidic and bind up calcium would help prevent stones. Just this year, Amitha Sampath, MD, from our group proved she was right: by using Polycitra K™ there was 3 times less risk of stones.(4) Since January 2006 at Hopkins, all children started on the diet are also started on Polycitra K™.