The effect of the classical and medium chain triglyceride ketogenic diet on vitamin and mineral levels

Background: The risk of nutritional deficiency in children on restrictive dietary treatments and a lack of ketogenic diet (KD)-specific UK supplements raises concerns about micronutrient status. Vitamin A, E, zinc, selenium and magnesium levels were therefore examined in children with intractable epilepsy treated with the KD. Methods: Plasma vitamins A and E, zinc, selenium and magnesium levels were measured at baseline and after 3, 6 and 12 months on the classical (n = 46) or medium chain triglyceride (MCT) (n = 45) KD in children aged 2-16 years, as part of a randomised trial, and pairwise comparisons with baseline were performed. Results: Data were available from 91 children. From baseline to 12 months, mean plasma vitamin A decreased from 1.41 mu mol L-1 to 1.13 mu mol L-1 in the classical group (P < 0.001) but increased from 1.52 lmol L-1 to 1.81 lmol L) 1 in the MCT group (P < 0.001). Mean plasma vitamin E increased from 22.7 mu mol L-1 to 33.2 mu mol L-1 in the classical group (P < 0.001) and from 22.3 mu mol L-1 to 23.3 mu mol L-1 in the MCT group (P < 0.05). No significant change in plasma zinc was seen at 12 months, although mean plasma selenium decreased from 0.95 lmol L-1 to 0.88 mu mol L-1 in the group as a whole (P < 0.05). Mean plasma magnesium decreased from 0.87 mmol L-1 to 0.83 mmol L-1 in the group as a whole (P < 0.001); when subdivided by KD type, this was limited to the classical group. Conclusions: Changes in plasma vitamins A and E and the decline in magnesium status after 12 months of KD treatment suggest that micronutrient status may be suboptimal in this group and that available formulations for KD supplementation may need reviewing.