Ketogenic diets are increasing in popularity and may offer a drug-free alternative to treatment for serious health conditions such as epilepsy and Alzheimer’s disease.
What is a ketogenic diet?
Ketogenic diets, in general, tend to be very low in carbohydrates, moderate in protein and high in fat. Developed in the 1920s by Russel Wilder as a treatment for epilepsy, they alter metabolism by decreasing available glucose, and increasing ketone body production in the liver, effectively stimulating the changes that occur during starvation. Ketones, namely acetoacetate, β-hydroxybutyrate, and their breakdown product, acetone, are small water-soluble molecules manufactured from fats and capable of travelling across cell membranes.
Different versions of the ketogenic diet are available depending on the age or health concern being addressed. The classic and modified versions use differing ratios of fat to non-fat foods, from 4:1 or 3:1 in classic ketogenic diets, to 2:1 or 1:1 in modified ketogenic diets. Medium chain ketogenic diet achieves ketosis by supplementing the diet with large amounts of medium chain fatty acids, which are disposed of the by liver as ketone bodies, irrespective of whether carbohydrates are ingested. This allows for greater flexibility regarding carbohydrate and protein intake, which can increase adherence to the diet, and reduce side effects. The modified Atkins diet, developed by the John Hopkins Hospital to offer a less restrictive ketogenic diet for teenagers and adults, follows a 1:1 ratio and has been found to be effective in controlling seizures in 45% of cases.
Ketogenic diets are used extensively in clinical settings and have been found to have a beneficial effect on numerous pathologies, including:
• Neurological disorders – there is evidence that ketogenic diets are beneficial for Multiple Sclerosis, Parkinson’s and Alzheimer’s disease, as well as improving behaviour and mood in bi-polar disorder and autism. Ketogenic diets have long been used to treat epilepsy, and research is supportive, with four major meta-analyses studies published in the past 10 years finding that ketogenic diets are effective in reducing seizure frequency in children with difficult-to-control epilepsy. Interestingly, research has found that in children being treated for epilepsy using ketogenic diets, those who included some calories from carbohydrates in their diet fared better in terms of seizure reduction, than those without any glucose present.
• Diabetes and obesity – ketogenic diets reduce glucose levels and improve insulin sensitivity, which may help improve type II diabetes, as well as blunting appetite and inducing weight loss. Studies also suggest that obese patients following a short-term ketogenic diet experienced a reduction in LDL cholesterol and triglycerides, with an increase in HDL cholesterol.
• PCOS – research suggests that adherence to a ketogenic diet and the lowered glucose, insulin and body weight that results may also benefit the hormone balance and symptoms of PCOS sufferers.
• Heart attacks or stroke – ketogenic diets have been shown to prevent brain damage after heart attacks, because ketones are able to reach blood- and glucose-deprived areas of tissue and nourish them.
• Cancer – cancer cells are known to be dependent on glucose metabolism for their growth and survival, and research has shown that in test tubes, cancer cells die when given ketones instead of glucose. Research is still lacking, but so far has shown positive results with brain cancer. Another way that ketogenic diets may help cancer prognosis is its link to chemotherapy efficacy and side effects – fasting, which mimics the ketogenic state, before chemotherapy treatment has been shown to increase toxicity to cancer cells, while reducing toxicity to healthy cells.
Long-term side effects
Possible side effects are numerous, below are the more commonly reported side effects of long-term ketogenic diets.
• Kidney stones – a common side effect in children.
• Nutrient deficiency – caused by a lack of plant food.
• Constipation – as well as other gastrointestinal disturbance. This may be caused by a reduction in the quantity and diversity of dietary fibre needed to create favourable conditions within the gut, in particular a healthy microbiome. A reduction of resistant starch in the diet, for example, may increases the pH of the stool, disrupting the balance of the bowel flora, enabling pathogenic strains to thrive. Resistant starch, like potato starch, doesn’t raise blood sugar levels and can be given to those following a long-term ketogenic diet to help feed good bacteria.
• Hormone imbalance – including reduced conversion of thyroid hormones, disruption to the menstrual cycle, and other related symptoms such as hair loss.
• Inflammatory disease – a long-term ketogenic diet may unfavourably impact on cholesterol levels and blood fats, and may alter immune response.
• Increase in cortisol – while there is conflicting evidence about ketogenic diets and their effect on cortisol, it appears that low carbohydrate diets may increase cortisol levels in susceptible individuals, potentially contributing to HPA axis dysfunction.
Written by Emma Rushe
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