Effects of a ketogenic diet on tumor metabolism and nutritional status in pediatric oncology patients: two case reports

Dietary restriction reduces angiogenesis and growth in an orthotopic mouse brain tumour model

Diet and lifestyle produce major effects on tumour incidence, prevalence, and natural history. Moderate dietary restriction has long been recognised as a natural therapy that improves health, promotes longevity, and reduces both the incidence and growth of many tumour types. Dietary restriction differs from fasting or starvation by reducing total food and caloric intake without causing nutritional deficiencies. No prior studies have evaluated the responsiveness of malignant brain cancer to dietary restriction. We found that a moderate dietary restriction of 30-40% significantly inhibited the intracerebral growth of the CT-2A syngeneic malignant mouse astrocytoma by almost 80%. The total dietary intake for the ad libitum control group (n=9) and the dietary restriction experimental group (n=10) was about 20 and 13 Kcal x day(-1), respectively. Overall health and vitality was better in the dietary restriction-fed mice than in the ad libitum-fed mice. Tumour microvessel density (Factor VIII immunostaining) was two-fold less in the dietary restriction mice than in the ad libitum mice, whereas the tumour apoptotic index (TUNEL assay) was three-fold greater in the dietary restriction mice than in the ad libitum mice. CT-2A tumour cell-induced vascularity was also less in the dietary restriction mice than in the ad libitum mice in the in vivo Matrigel plug assay. These findings indicate that dietary restriction inhibited CT-2A growth by reducing angiogenesis and by enhancing apoptosis. Dietary restriction may shift the tumour microenvironment from a proangiogenic to an antiangiogenic state through multiple effects on the tumour cells and the tumour-associated host cells. Our data suggest that moderate dietary restriction may be an effective antiangiogenic therapy for recurrent malignant brain cancers.

Caveats when considering ketogenic diets for the treatment of pyruvate dehydrogenase complex deficiency

OBJECTIVES

We conducted a critical assessment of the use of diets high in fat and low in carbohydrate ("ketogenic") in the treatment of children with congenital lactic acidosis caused by mutations in the mitochondrial pyruvate dehydrogenase complex (PDC).

STUDY DESIGN

The dietary composition of 18 subjects (11 from literature sources and 7 previously unpublished cases) was analyzed for nutrient composition. The biochemical and clinical responses to a long-term ketogenic regimen were also evaluated.

RESULTS

There was lack of uniformity in the proportion of fat calories administered and in the fatty acid composition of the diets. Ketogenic diets are also generally high in protein, compared with the recommended dietary allowance for age. Patient response to these regimens also varied considerably.

CONCLUSIONS

Although ketogenic diets have become the standard of care for the treatment of PDC deficiency, data to support their use are based on a few uncontrolled case reports in which dietary composition varied widely. Furthermore, there are several theoretical reasons for concern about the long-term safety of high-fat, low-carbohydrate diets. A controlled, prospective evaluation of the risks and benefits of these regimens for patients with PDC deficiency is required to establish rational nutritional guidelines.

Implementing a ketogenic diet based on medium-chain triglyceride oil in pediatric patients with cancer

Traditionally, a ketogenic diet is given to drug-resistant children with epilepsy to improve seizure control. Inducing a ketogenic state in patients with cancer may be a useful adjunct to cancer treatment by affecting tumor glucose metabolism and growth while maintaining the patient's nutritional status. A ketogenic diet consisting of 60% medium-chain triglyceride (MCT) oil, 20% protein, 10% carbohydrate, and 10% other dietary fats was provided to a select group of pediatric patients with advanced-stage cancer to test the effects of dietary-induced ketosis on tumor glucose metabolism. Issues of tolerance and compliance for patients consuming an oral diet (consisting of normal table foods and daily MCT oil "shakes") and for patients receiving an enteral formula are reviewed. Preliminary use of the MCT oil-based diet suggests a potential in pediatric patients with cancer.