Chronic Diseases

Peer-Reviewed Scientific Articles​

Carbohydrate Restriction has a More Favorable Impact on the Metabolic Syndrome than a Low Fat Diet

URL: https://link.springer.com/article/10.1007/s11745-008-3274-2

Journal: Lipids

Publication Date: 12/2008

Summary: We recently proposed that the biological markers improved by carbohydrate restriction were precisely those that define the metabolic syndrome (MetS), and that the common thread was regulation of insulin as a control element. We specifically tested the idea with a 12-week study comparing two hypocaloric diets (~1,500 kcal): a carbohydrate-restricted diet (CRD) (%carbohydrate:fat:protein = 12:59:28) and a low-fat diet (LFD) (56:24:20) in 40 subjects with atherogenic dyslipidemia. Both interventions led to improvements in several metabolic markers, but subjects following the CRD had consistently reduced glucose (−12%) and insulin (−50%) concentrations, insulin sensitivity (−55%), weight loss (−10%), decreased adiposity (−14%), and more favorable triacylglycerol (TAG) (−51%), HDL-C (13%) and total cholesterol/HDL-C ratio (−14%) responses. In addition to these markers for MetS, the CRD subjects showed more favorable responses to alternative indicators of cardiovascular risk: postprandial lipemia (−47%), the Apo B/Apo A-1 ratio (−16%), and LDL particle distribution. Despite a threefold higher intake of dietary saturated fat during the CRD, saturated fatty acids in TAG and cholesteryl ester were significantly decreased, as was palmitoleic acid (16:1n-7), an endogenous marker of lipogenesis, compared to subjects consuming the LFD. Serum retinol binding protein 4 has been linked to insulin-resistant states, and only the CRD decreased this marker (−20%). The findings provide support for unifying the disparate markers of MetS and for the proposed intimate connection with dietary carbohydrate. The results support the use of dietary carbohydrate restriction as an effective approach to improve features of MetS and cardiovascular risk.

Key Takeaways

Carbohydrate restriction diets showed better outcomes than low fat diets. The carbohydrate restrictive diet had a greater improvement in blood sugar, insulin, insulin sensitivity, weight loss, body fat, triglycerides, HDL, total cholesterol, and other markers for cardiovascular health.

Nutrition and Alzheimer’s disease: The detrimental role of a high carbohydrate diet

URL: https://www.ejinme.com/article/S0953-6205(11)00004-5/fulltext

Journal: European Journal of Internal Medicine

Publication Date: 04/2011

Summary: Alzheimer’s disease is a devastating disease whose recent increase in incidence rates has broad implications for rising health care costs. Huge amounts of research money are currently being invested in seeking the underlying cause, with corresponding progress in understanding the disease progression. In this paper, we highlight how an excess of dietary carbohydrates, particularly fructose, alongside a relative deficiency in dietary fats and cholesterol, may lead to the development of Alzheimer’s disease. A first step in the pathophysiology of the disease is represented by advanced glycation end-products in crucial plasma proteins concerned with fat, cholesterol, and oxygen transport. This leads to cholesterol deficiency in neurons, which significantly impairs their ability to function. Over time, a cascade response leads to impaired glutamate signaling, increased oxidative damage, mitochondrial and lysosomal dysfunction, increased risk to microbial infection, and, ultimately, apoptosis. Other neurodegenerative diseases share many properties with Alzheimer’s disease, and may also be due in large part to this same underlying cause.

Key Takeaways

Excess carbohydrates in the diet play an important role in the development of Alzheimer's disease. Carbohydrates in the diet are broken down to sugars that when present in excessive quantities allows them to bind to proteins and impair their function. When these sugars bind to proteins essential for carrying fat, cholesterol, and oxygen to the brain, signaling mechanisms in the brain become impaired, which leads to inflammation, mitochondrial and lysosomal dysfunction, infection susceptibility, and cell death.

Short-term weight loss and hepatic triglyceride reduction: evidence of a metabolic advantage with dietary carbohydrate restriction

URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3076656/

Journal: American Journal of Clinical Nutrition

Publication Date: 05/2011

Summary: Individuals with nonalcoholic fatty liver disease (NAFLD) have excess intrahepatic triglycerides. This is due, in part, to increased hepatic synthesis of fat from carbohydrates via lipogenesis. Although weight loss is currently recommended to treat NAFLD, little attention has been given to dietary carbohydrate restriction. The aim of this study was to determine the effectiveness of 2 wk of dietary carbohydrate and calorie restriction at reducing hepatic triglycerides in subjects with NAFLD. Eighteen NAFLD subjects (n = 5 men and 13 women) with a mean (±SD) age of 45 ± 12 y and a body mass index (in kg/m2) of 35 ± 7 consumed a carbohydrate-restricted (<20 g/d) or calorie-restricted (1200–1500 kcal/d) diet for 2 wk. Hepatic triglycerides were measured before and after intervention by magnetic resonance spectroscopy.  Mean (±SD) weight loss was similar between the groups (−4.0 ± 1.5 kg in the calorie-restricted group and −4.6 ± 1.5 kg in the carbohydrate-restricted group; P = 0.363). Liver triglycerides decreased significantly with weight loss (P < 0.001) but decreased significantly more (P = 0.008) in carbohydrate-restricted subjects (−55 ± 14%) than in calorie-restricted subjects (−28 ± 23%). Dietary fat (r = 0.643, P = 0.004), carbohydrate (r = −0.606, P = 0.008), posttreatment plasma ketones (r = 0.755, P = 0.006), and respiratory quotient (r = −0.797, P < 0.001) were related to a reduction in liver triglycerides. Plasma aspartate, but not alanine, aminotransferase decreased significantly with weight loss (P < 0.001). Two weeks of dietary intervention (≈4.3% weight loss) reduced hepatic triglycerides by ≈42% in subjects with NAFLD; however, reductions were significantly greater with dietary carbohydrate restriction than with calorie restriction. This may have been due, in part, to enhanced hepatic and whole-body oxidation.

Key Takeaways

Non-Alcoholic Fatty Liver Disease is partly caused by excess dietary carbohydrates, which leads to fat production in the liver. 18 subjects completed 2 weeks of either carbohydrates restricted diets or calorie restricted diets. Both diets showed weight loss and reduction in liver fat, but the low carbohydrate diet showed greater reduction in liver fat.

The ketogenic diet as a treatment paradigm for diverse neurological disorders

URL: https://www.frontiersin.org/articles/10.3389/fphar.2012.00059/full

Journal: Frontiers in Pharmacology

Publication Date: 04/2012

Summary: Dietary and metabolic therapies have been attempted in a wide variety of neurological diseases, including epilepsy, headache, neurotrauma, Alzheimer disease, Parkinson disease, sleep disorders, brain cancer, autism, pain, and multiple sclerosis. The impetus for using various diets to treat – or at least ameliorate symptoms of – these disorders stems from both a lack of effectiveness of pharmacological therapies, and also the intrinsic appeal of implementing a more “natural” treatment. The enormous spectrum of pathophysiological mechanisms underlying the aforementioned diseases would suggest a degree of complexity that cannot be impacted universally by any single dietary treatment. Yet, it is conceivable that alterations in certain dietary constituents could affect the course and impact the outcome of these brain disorders. Further, it is possible that a final common neurometabolic pathway might be influenced by a variety of dietary interventions. The most notable example of a dietary treatment with proven efficacy against a neurological condition is the high-fat, low-carbohydrate ketogenic diet (KD) used in patients with medically intractable epilepsy. While the mechanisms through which the KD works remain unclear, there is now compelling evidence that its efficacy is likely related to the normalization of aberrant energy metabolism. The concept that many neurological conditions are linked pathophysiologically to energy dysregulation could well provide a common research and experimental therapeutics platform, from which the course of several neurological diseases could be favorably influenced by dietary means. Here we provide an overview of studies using the KD in a wide panoply of neurologic disorders in which neuroprotection is an essential component.

Key Takeaways

The ketogenic diet has been shown to be neuroprotective and used in the treatment of epilepsy. The exact mechanisms of how the diet is protective against epilepsy is unclear, but it is thought that energy regulation plays a major role. Because the ketogenic diet does not rely on continuous inputs of carbohydrates, blood sugar levels remain constant. Without these large fluctuations in blood sugar, the energy supply to the brain is stable resulting in a reduction in seizures. Additionally, ketone bodies produced by burning fat are neuroprotective in their own way through a variety of actions. This dietary approach has been shown to be helpful in treating other neurologic conditions such as headache, neurotrauma, Alzheimer disease, Parkinson disease, sleep disorders, brain cancer, autism, pain, and multiple sclerosis.

Is the restricted ketogenic diet a viable alternative to the standard of care for managing malignant brain cancer?

URL: https://www.sciencedirect.com/science/article/abs/pii/S0920121111002063?via%3Dihub

Journal: Epilepsy Research

Publication Date: 07/2012

Summary: Malignant brain cancer persists as a major disease of morbidity and mortality. The failure to recognize brain cancer as a disease of energy metabolism has contributed in large part to the failure in management. As long as brain tumor cells have access to glucose and glutamine, the disease will progress. The current standard of care provides brain tumors with access to glucose and glutamine. The high fat low carbohydrate ketogenic diet (KD) will target glucose availability and possibly that of glutamine when administered in carefully restricted amounts to reduce total caloric intake and circulating levels of glucose. The restricted KD (RKD) targets major signaling pathways associated with glucose and glutamine metabolism including the IGF-1/PI3K/Akt/Hif pathway. The RKD is anti-angiogenic, anti-invasive, anti-inflammatory, and pro-apoptotic when evaluated in mice with malignant brain cancer. The therapeutic efficacy of the restricted KD can be enhanced when combined with drugs that also target glucose and glutamine. Therapeutic efficacy of the RKD was also seen against malignant gliomas in human case reports. Hence, the RKD can be an effective non-toxic therapeutic option to the current standard of care for inhibiting the growth and invasive properties of malignant brain cancer.

Key Takeaways

Brain cancers can be thought of as a disease of energy regulation. They utilize glucose and glutamine to survive and grow. This is why standards of care may be outperformed by dietary approaches that stabilize the glucose input to the brain such as the ketogenic diet. Additionally a calorie restricted ketogenic diet may target the utilization of glutamine by the cancer. A calorie restricted ketogenic diet in mice with malignant brain cancer was shown to be anti-inflammatory, reduce invasion of the cancer, reduce access of cancer to nutrients by preventing blood vessel formation, and induce death of the cancer cells.

Effect of low-calorie versus low-carbohydrate ketogenic diet in type 2 diabetes

URL: https://www.sciencedirect.com/science/article/abs/pii/S0899900712000731?via%3Dihub

Journal: Nutrition

Publication Date: 10/2012

Summary: Effective diabetic management requires reasonable weight control. Previous studies from our laboratory have shown the beneficial effects of a low-carbohydrate ketogenic diet (LCKD) in patients with type 2 diabetes after its long term administration. Furthermore, it favorably alters the cardiac risk factors even in hyperlipidemic obese subjects. These studies have indicated that, in addition to decreasing body weight and improving glycemia, LCKD can be effective in decreasing antidiabetic medication dosage. Similar to the LCKD, the conventional low-calorie, high nutritional value diet is also used for weight loss. The purpose of this study was to understand the beneficial effects of LCKD compared with the low-calorie diet (LCD) in improving glycemia. Three hundred and sixty-three overweight and obese participants were recruited from the Al-Shaab Clinic for a 24-wk diet intervention trial; 102 of them had type 2 diabetes. The participants were advised to choose LCD or LDKD, depending on their preference. Body weight, body mass index, changes in waist circumference, blood glucose level, changes in hemoglobin and glycosylated hemoglobin, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglycerides, uric acid, urea and creatinine were determined before and at 4, 8, 12, 16, 20, and 24 wk after the administration of the LCD or LCKD. The initial dose of some antidiabetic medications was decreased to half and some were discontinued at the beginning of the dietary program in the LCKD group. Dietary counseling and further medication adjustment were done on a biweekly basis. The LCD and LCKD had beneficial effects on all the parameters examined. Interestingly, these changes were more significant in subjects who were on the LCKD as compared with those on the LCD. Changes in the level of creatinine were not statistically significant. This study shows the beneficial effects of a ketogenic diet over the conventional LCD in obese diabetic subjects. The ketogenic diet appears to improve glycemic control. Therefore, diabetic patients on a ketogenic diet should be under strict medical supervision because the LCKD can significantly lower blood glucose levels.

Key Takeaways

363 overweigh or obese patients (102 of them had type 2 diabetes) chose either a low carbohydrate ketogenic diet or a low calorie diet. The study lasted for 24 weeks, and both diets showed improvement in body weight, BMI, waist circumference, Hb-A1C, blood lipids, and kidney function tests. However, the low carb ketogenic group showed greater improvements across the board.

Low-carbohydrate ketogenic diets, glucose homeostasis, and nonalcoholic fatty liver disease

URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3679496/

Journal: Current Opinions in Clinical Nutrition and Metabolic Care

Publication Date: 07/2012

Summary: Obesity-associated nonalcoholic fatty liver disease (NAFLD) is highly prevalent, for which weight loss is the generally recommended clinical management. Low-carbohydrate ketogenic diets have been successful in promoting weight loss, but variations in the range of metabolic responses to these diets indicate that the effects of altering macronutrient content are not completely understood. This review focuses on the most recent findings that reveal the relationship between low-carbohydrate diets and NAFLD in rodent models and humans. Low-carbohydrate diets have been shown to promote weight loss, decrease intrahepatic triglyceride content, and improve metabolic parameters of patients with obesity. These ketogenic diets also provoke weight loss in rodents. However, long-term maintenance on a ketogenic diet stimulates the development of NAFLD and systemic glucose intolerance in mice. The relationship between ketogenic diets and systemic insulin resistance in both humans and rodents remains to be elucidated. Because low-carbohydrate ketogenic diets are increasingly employed for treatment of obesity, NAFLD, and neurological diseases such as epilepsy, understanding the long-term systemic effects of low-carbohydrate diets is crucial to the development of efficacious and safe dietary interventions.

Key Takeaways

Low Carbohydrate Ketogenic Diets are shown to be highly effective for weight loss and reduction of fatty liver. However, long term ketogenic diets in mice induced fatty liver. This study calls for further research in long term low carbohydrate diets to assess unintended health consequences. We must ask the question: Are outcomes in mice going to be the same in humans? Likely not as we are different species, which is why this study calls for more long term data in humans to assess safety.

Dietary ketosis enhances memory in mild cognitive impairment

URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3116949/

Journal: Nuerobiology of Aging

Publication Date: 02/2012

Summary: We randomly assigned 23 older adults with Mild Cognitive Impairment to either a high carbohydrate or very low carbohydrate diet. Following the six-week intervention period, we observed improved verbal memory performance for the low carbohydrate subjects (p = 0.01) as well as reductions in weight (p < 0.0001), waist circumference (p < 0.0001), fasting glucose (p = 0.009), and fasting insulin (p = 0.005). Level of depressive symptoms was not affected. Change in calorie intake, insulin level, and weight were not correlated with memory performance for the entire sample, although a trend toward a moderate relationship between insulin and memory was observed within the low carbohydrate group. Ketone levels were positively correlated with memory performance (p = 0.04). These findings indicate that very low carbohydrate consumption, even in the short-term, can improve memory function in older adults with increased risk for Alzheimer’s disease. While this effect may be attributable in part to correction of hyperinsulinemia, other mechanisms associated with ketosis such as reduced inflammation and enhanced energy metabolism also may have contributed to improved neurocognitive function. Further investigation of this intervention is warranted to evaluate its preventive potential and mechanisms of action in the context of early neurodegeneration.

Key Takeaways

Low carbohydrate ketogenic diets showed improved memory, weight loss, blood sugar, and fasting insulin in adults with mild cognitive impairment. Further research is needed to determine whether the improvement is due to correction of high insulin levels, or the reduction in inflammation brought about by the ketosis.

Consuming a hypocaloric high fat low carbohydrate diet for 12 weeks lowers C-reactive protein, and raises serum adiponectin and high density lipoprotein-cholesterol in obese subjects

URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3845365/

Journal: Metabolism

Publication Date: 12/2013

Summary: High fat, low carbohydrate (HFLC) diets have become popular tools for weight management. We sought to determine the effects of a HFLC diet compared to a low fat high carbohydrate (LFHC) diet on the change in weight loss, cardiovascular risk factors and inflammation in subjects with obesity. Obese subjects (29.0–44.6 kg/m2) recruited from Boston Medical Center were randomized to a hypocaloric LFHC (n=26) or HFLC (n=29) diet for 12 weeks. The age range of subjects was 21–62 years. As a percentage of daily calories, the HFLC group consumed 33.5% protein, 56.0% fat and 9.6% carbohydrate and the LFHC group consumed 22.0% protein, 25.0% fat and 55.7% carbohydrate. The change in percent body weight, lean and fat mass, blood pressure, flow mediated dilation, hip:waist ratio, hemoglobin A1C, fasting insulin and glucose, and glucose and insulin response to a 2 h oral glucose tolerance test did not differ (P>0.05) between diets after 12 weeks. The HFLC group had greater mean decreases in serum triglyceride (P=0.07), and hs-CRP (P=0.03), and greater mean increases in HDL cholesterol (P=0.004), and total adiponectin (P=0.045) relative to the LFHC. Secreted adipose tissue adiponectin or TNF-α did not differ after weight loss for either diet. Relative to the LFHC group, the HFLC group had greater improvements in blood lipids and systemic inflammation with similar changes in body weight and composition. This small-scale study suggests that HFLC diets may be more beneficial to cardiovascular health and inflammation in free-living obese adults compared to LFHC diets.

Key Takeaways

This study compared high fat low carb diets to low fat high carb diets for 12 weeks in obese adults. Both diets saw similar levels of change in body weight, lean and fat mass, blood pressure, blood sugar, and insulin. However, the high fat low carb diet led to decreases in triglycerides and CRP (a marker of inflammation). The high fat low carb group also saw increase in HDL and adiponectin (a marker of insulin sensitivity).

Improvements in Glucose Metabolism and Insulin Sensitivity with a Low-Carbohydrate Diet in Obese Patients with Type 2 Diabetes

URL: https://www.ncbi.nlm.nih.gov/pubmed/24015695

Journal: Journal of the American College of Nutrition

Publication Date: 04/2013

Summary: The optimal diet for weight loss in type 2 diabetes remains controversial. This study examined a low-carbohydrate, high-fat diet with detailed physiological assessments of insulin sensitivity, glycemic control, and risk factors for cardiovascular disease. Fourteen obese patients (body mass index [BMI] 40.6 ± 4.9 kg/m2) with type 2 diabetes were recruited for an “Atkins”-type low-carbohydrate diet. Measurements were made at 0, 12, and 24 weeks of weight, insulin sensitivity, HbA1c, lipids, and blood pressure. Twelve completers lost a mean of 9.7 ± 1.8 kg over 24 weeks attributable to a major reduction in carbohydrates and resultant reduction in total energy intake. Glycemic control significantly improved (HbA1c −1.1 ± 0.25%) with reductions in hypoglycemic medication. Fasting glucose, homeostasis model assessment (HOMA), and area under the curve (AUC) glucose (intravenous glucose tolerance test [IVGTT]) were significantly reduced by week 12 (p < 0.05). There were nonsignificant improvements in insulin sensitivity (SI) at week 12 ( p = 0.19) and week 24 ( p = 0.31). Systolic blood pressure was reduced (mean −10.0 mmHg between weeks 0 and 24, p = 0.13). Mean high-density lipoprotein (HDL), low-density lipoprotein (LDL), and total cholesterol all increased. The ratio of total: HDL cholesterol and triglycerides was reduced. A low-carbohydrate diet was well tolerated and achieved weight loss over 24 weeks in subjects with diabetes. Glycemic control improved with a reduction in requirements for hypoglycemic agents.

Key Takeaways

In this study, a low carbohydrate diet was administered to 14 obese type 2 diabetics for 24 weeks. The subjects saw improvements across the board in weight, blood sugar, and blood pressure. Total, HDL, and LDL cholesterol all increased, but with good ratios. Overall glycemic control was improved with a lower requirement for diabetic medications.

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