NEW ORLEANS — The May 2021 Issue of the online, peer-reviewed journal Nutrients provided an excellent narrative review of the ketogenic diet from researchers in the Department of Biology, Western Kentucky University.
Ketogenic diets, which traditionally have emphasized keeping total carbohydrate intake to less than 50 grams per day, have increased in usage from their inception in the 1930s to treat epilepsy. Restricting carbohydrate consumption, emphasizing moderate protein intake, and increasing caloric consumption from fat, causes the body to draw more from fat for energy than from glucose metabolism.
According to the Nutrients research – The Potential Health Benefits of the Ketogenic Diet: A Narrative Review – “recent studies utilizing Low-carbohydrate, High-fat (LCHF) diets, such as the ketogenic diet, show promise in helping patients lose weight, reverse the signs of metabolic syndrome, reduce, or eliminate insulin requirements for type II diabetics, reduce inflammation, improve epigenetic profiles, alter the microbiome, improve lipid profiles, supplement cancer treatments, and potentially increase longevity and brain function.”
That’s important since WebMD estimates that 27 million people are Type 2 diabetic – 86 million pre-diabetics. In addition, the Centers of Disease Control and Prevention (CDC) says almost 40% of adults and around 20% of American children are obese.
The Western Kentucky reviewers segment the ketogenic diet (KD) into two classifications versus the standard American diet. The therapeutical keto diet’s caloric distribution is 5% carbohydrate, 5% protein, and 90% fat, while the standard keto variation is 5% carbohydrate, 20% protein, and 75% fat. The standard American diet is 55% carbohydrate, 15% protein, and 30% fat.
The researchers point out that “ketosis is normally achieved through either fasting or carbohydrate restriction. It is important to clarify that a low-carb diet typically refers to a diet with an intake of 50 to 150 g of carbohydrate per day. However, although this is a lower amount of carbohydrates than the standard American diet, it is not low enough to enter nutritional ketosis. Only when a patient restricts carbohydrates to less than 50 g/day will the body be incapable of fueling the body by glucose and will switch to burning fat.”
The areas of focus by the Kentucky investigators centered on the effects of the keto diet (KD) on the microbiome (intestinal bacteria), epigenome (changes “on top” of the genome, which modify our gene expression), diabetes, weight loss, cardiovascular disease, and cancer.
The microbiome is composed of trillions of microscopic organisms housed in the intestinal tract – supporting 70% of our immune function. While there is limited long-term data on the effects of the keto diet, “based on various studies, many predict that the diet will positively affect the microbiome by increasing the Bacteroidetes and Bifidobacteria species associated with improved health and decreasing microbial species known to increase health risks,” comment the reviewers.
As for the epigenome, our heritable markers, it’s suggested that by changing our environment to a more favorable status, we can affect our genetic predisposition to heritable disease risk. According to the reviewers, “the benefits of the ketogenic diet might also go beyond treating existing disease, and instead help prevent chronic and degenerative disease.”
From a weight-loss perspective, the KD dieter should be followed under the direction of the primary care physician, due to the potential complexity of the individual’s current medical status. The researchers point to a long-term (56 weeks) ketogenic study conducted on 66 obese people with a body mass index (BMI) >30 (obese).
“All patients were instructed to eat <20 grams (g) of carbohydrates in the form of green vegetables and salads for 12 weeks and then they could increase the carbohydrates to 40 g/day for the remainder of the study. The weight and body mass index of all patients decreased significantly.”
More interestingly, comment the reviewers, “the patients were advised to maintain a state of nutritional ketosis and they were able to show continued decreases in both BW (bodyweight) and BMI throughout the study.”
The CDC says there are currently in the US estimated 30-millions diabetics – 84 million with pre-diabetes, which predicts that 45% of Americans are either diabetic or pre-diabetic. As with the objective of weight loss, the prediabetic or diabetic person should be followed by their primary care physician to monitor appropriate metabolic criteria affected by the KD.
A few randomized controlled studies looked at the effects of the KD on diabetes. One study noted was recently conducted at Indiana University—one of the first long-term studies that required the use of routine blood tests to determine the patients’ state of nutritional ketosis, while maintaining a KD diet. Patients were highly compliant and experienced improved diabetic conditions.
“The diet intervention also reversed the diabetic status of some patients, whose HbA1cs became normal. The 2-year follow-up to this study revealed that 74% of the KD group remained enrolled. This group had a significant improvement in HbA1c, fasting glucose, and fasting insulin while the usual care group had no changes from baseline.”
From a cardiovascular disease prevention and lipid (fat) lowering perspective, the KD, with its potential for a high saturated fat intake, has resulted in controversy. Interestingly, the Kentucky reviewers say only a few studies have evaluated the health impact of very high fat intake on overall health – including weight management, lipid profiles, and inflammatory markers.
“One study compared a KD to the standard American diet (SAD) and the SAD plus exercise. Not only did the KD outperform the other groups in multiple health outcomes, but it also showed a much more significant decline in triglycerides.”
Cancer is the second leading cause of death in the US next to heart disease. The KD’s impact on cancer has mixed reviews.
“The data of the effect of KD in human patients is limited mostly to case studies and cohort studies. A meta-analysis of 24 human studies, found that 42% found that the KD can reduce tumor growth. In addition, it has been found that most human studies had positive impacts, with many other studies found it stabilized disease, and one study found a pro-tumorigenic effect of the KD. However, another review of 14 studies of the use of KD in cancer found mixed results.”
Until more diverse long-term research of controlled trials on various disease populations is completed, it’s best to check with your doctor, before embarking on dietary experimentation. Let’s leave that to the experts.
For more information, go to maxwellnutritiom.com.