Patients and/or their parents must be made aware of the full implications of the diet and agree prior to implementation¹.

Evidence does not bear out the theoretical risk that the high-fat ketogenic diet is a risk factor for cardiovascular disease, though it is fair to say that the long-term effects have not been extensively evaluated^2,3,4. Regularly monitoring serum lipids would seem pertinent. Even though it was successful, the ketogenic diet has had to be stopped in one individual with seriously high levels of triglycerides, to prevent a possible life-threatening pulmonary embolism⁵.

Renal calculi have been documented in some patients^2,3,4. Increased levels of plasma uric-acid have been found in patients following both long-chain triglyceride LCT and medium-chain triglyceride MCT diets, possibly as a result of altered renal tubular function³.

Adequate fluid intake can help minimise this side-effect³. However, too much fluid can dilute ketones, reducing the efficacy of the diet¹. Ideally, liquid intake should be restricted to about 75% of normal⁶. Decreased fluid intake serves to compound the effects of the profoundly ketotic state by producing more acidic urine⁷. Plasma uric-acid levels should be regularly monitored^2,3. Screening for haematuria may alert practitioners to possible stone formation⁸.

Physical growth is moderately retarded in most patients following the diet⁴. This appears a temporary disturbance as re-examination of patients 15-20 years later found all of them to be within limits of normal for their chronological age⁴. Others have found that growth was not affected in the short-term and most measurements of stature continued to follow normal centile lines³.

Energy requirements should be carefully calculated and re-evaluated every few months and the diet adjusted accordingly⁹. Regularly monitor growth measurements.

Various vitamin and mineral deficiencies might occur including: calcium^4,6, folate⁶, zinc^5,6, iron^5,6, B complex^4,6 vitamin C^4,6 and water-soluble vitamin D⁵.

Routine supplementation with a quality, sugar-free multi-nutrients and calcium should be given⁴ particularly as optic neuropathy has been reported in patients not receiving vitamins^2,6 and can lead to blindness¹⁰.

Vomiting can occur during the preliminary starvation period and at any point during the diet⁴. The starvation period should be interrupted and resumed at a later date⁴. If the patient does not respond to symptomatic treatment whilst on the diet then it is advisable to discontinue all foods for 24-48 hours and give only water⁴. Nausea, vomiting and abdominal discomfort is more common whilst establishing the MCT diet^2,3 and can be overcome by temporarily reducing the amount of MCT oil before gradually increasing again^2,3.

Constipation can arise as the diet provides less bulk⁵. An enema, mineral oil, unsweetened agar, Epsom salts or unsweeted fluid extract of cascara may be prescribed when indicated⁴. An adequate intake of fluid helps⁶.

Valproate, a common anti-epileptic drug, has been shown to inhibit ketogenesis and deplete glycogen stores in mice^8,11. Diets consisting mainly of ketogenic substances, may drive the body into the breakdown of proteins for energy, which could become life-threatening^8,11.

Untreated ketosis may lead to ketoacidosis, coma and death. Ketoacidosis is characterised by: fruity breath odour, mental confusion, dyspnoea, nausea, vomiting, dehydration, weight loss. Patients/parents/staff should be aware of symptoms and urgent medical treatment sought¹⁰.

This has been documented in children with seizures treated with the ketogenic diet^8,12. Consideration should be given to stopping iatrogenic causes of ketosis in patients if a bacterial infection develops¹².

The ketogenic diet is contraindicated in such cases, as it can kill within hours⁵. Routine biochemical testing for raised levels: acylcarnitine:free carnitine ratio, octanoate and Cis-4-decenoate to identify sufferers prior to implementing the diet⁵. Cell culture of skin fibroblasts can also be used¹³.

It is imperative to release the dietary restrictions slowly over 1-2 weeks. Sudden sugar consumption might precipitate a seizure, due to the likely anti-convulsive action of ketones¹.

1. Epilepsy, 4.23 Therapeutic Dietetics for Disease States, p 489-497
2. Prasad A, Stafstrom C, Holmes G, Alternative Epilepsy Therapies: The Ketogenic Diet, Immunoglobulins, and Steroids, Epilepsia, Vol 37, Suppl 1, 1996
3. Schwartz R, Boyes S, Aynsley-Green A. Metabolic Effects of Three Ketogenic Diets in the Treatment of Severe Epilepsy, Dvpt Med and Child Neurology, 1989, 31, 152-160
4. Dietary Treatment of Epilepsy, Chapter 7, Comprehensive Management of Epilepsy
5. Egger J, Prof, MSc lecture, Surrey University, July 2000
6. http://icarus.cc.uic.edu/-ktao1KETOFINAL2.htm
7. Herzberg G, Fivush B, Kinsman S, Gearhart J, Urolithiasis associated with the ketogenic diet, Journal of Paediatrics, Vol 117, No 5p 743-745
8. www.medsch.ucla.edu/som/ddo/biolchem/nut-1998/ByteV3N2/v3n2chao.html
9. www.mynchen.demon.co.uk
10. Mosby’s Medical, Nursing & Allied Health Dictionary, 5^th Edn, Mosby, 1998
11. Thurston J, Carroll J, Dodson, W, Hauhart R, Tasch V, Chronic Valproate administration reduces fasting ketonemia in children, Neurology, Oct 1983, 33, 1349
12. Woody R, Steele R, Knappie W, Pilkington N, Impaired neutrophil function in children with seizures treated with the ketogenic diet, Journal of Paediatrics, Sept 1989, Vol 115 No 3, p 427-430
13. www.cwru.edu/med/CIDEM/assaygen.htm