Ketogenic diets and their use for cancer
Nancy Scanlan, DVM
What are ketogenic diets? If you know about the Atkins diet, you know that this is a diet that creates ketone bodies. A ketone body is produced by the liver and is a by-product of fat breakdown. Ketones can be used by the body for energy, but cancer can’t use them. In contrast, glucose (a sugar) is used by both regular cells and cancer cells. In fact, cancer cells use so much glucose that they stimulate the body to create higher and higher levels. If you can lower the amount of glucose and increase the amount of ketone bodies, you will starve cancer cells while feeding normal cells.
There are 4 main types of ketogenic diet: classic, MCT (medium chain triglycerides), modified Atkins, and Low Glycemic Index (LGI) diet. The MCT diet should not be used in pets. The modified Atkins diet restricts carbohydrates but not protein or calories. The LGI diet restricts carbohydrates but does not try to generate ketone bodies. The diet that has shown the most promise for humans with highly malignant brain cancer, and for dogs with all kinds of cancer, is the classic ketogenic diet.
In the classic diet, 4 parts of fat are fed for every single part of protein. No additional carbohydrates are added, but vitamins and minerals are needed for proper metabolism. The biggest problem initially for cancer patients is diarrhea if the diet is changed too quickly. So the absolute shortest time to change over gradually to the new diet is 7 days. In humans, sometimes constipation is a problem, and fiber can be added to help. High fat diets can also create pancreatitis, but this effect is most often seen when a pet gets into a lot of fat and has a large amount all of a sudden, after being on a normal diet.
The total amount fed should only be the normal amount of calories. If people or pets are allowed to eat as much as they want, there is little to no anti-cancer effect. This can be hard for the pet owner since the amount of food is so small (because fat is so high in calories.) But if the diet is followed correctly, cancer stops spreading and tumors will usually shrink. The only way to really tell if the diet is ketogenic and doing its job is a blood test. Along with increased ketone bodies in the blood, markers for inflammation will decrease.
If the diet is continued too long, the muscles can start shrinking since the amount of protein is relatively small. It is usually safe after about 4 months to gradually start increasing the protein. At that time, the body can maintain ketosis on a lower ratio of fat to protein, ending up as 2 parts fat to 1 part protein or even as low as half fat, half protein. Again, the only way to make sure is to do blood tests. To make sure it stays that way, the 4:1 high fat diet can be feed for one week every 2 months, to stimulate the body to keep metabolising fat.
High glycemic carbohydrates should never be fed with this diet. No kibble, no dog cookies, nothing with sugar. Those foods feed cancer.
Humans with glioblastoma multiforme (a highly malignant brain cancer with very poor response to conventional therapy) have lived much longer with this diet. A small trial in dogs with cancer has stopped cancer spread and decreased tumors. The amount of success depends on how far the cancer has progressed, and which type of cancer it is. The treatment can be used with or without conventional therapy. If the cancer is too advanced, conventional therapy such as surgery might be needed at the beginning to give the patient enough time to respond to the diet.
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