Is there a role for carbohydrate restriction in the treatment and prevention of cancer
TL;DR: The possible beneficial effects of low CHO diets on cancer prevention and treatment are addressed, with emphasis on the role of insulin and IGF1 signaling in tumorigenesis as well as altered dietary needs of cancer patients.
Abstract: Over the last years, evidence has accumulated suggesting that by systematically reducing the amount of dietary carbohydrates (CHOs) one could suppress, or at least delay, the emergence of cancer, and that proliferation of already existing tumor cells could be slowed down. This hypothesis is supported by the association between modern chronic diseases like the metabolic syndrome and the risk of developing or dying from cancer. CHOs or glucose, to which more complex carbohydrates are ultimately digested, can have direct and indirect effects on tumor cell proliferation: first, contrary to normal cells, most malignant cells depend on steady glucose availability in the blood for their energy and biomass generating demands and are not able to metabolize significant amounts of fatty acids or ketone bodies due to mitochondrial dysfunction. Second, high insulin and insulin-like growth factor (IGF)-1 levels resulting from chronic ingestion of CHO-rich Western diet meals, can directly promote tumor cell proliferation via the insulin/IGF1 signaling pathway. Third, ketone bodies that are elevated when insulin and blood glucose levels are low, have been found to negatively affect proliferation of different malignant cells in vitro or not to be usable by tumor cells for metabolic demands, and a multitude of mouse models have shown antitumorigenic properties of very low CHO ketogenic diets. In addition, many cancer patients exhibit an altered glucose metabolism characterized by insulin resistance and may profit from an increased protein and fat intake. In this review, we address the possible beneficial effects of low CHO diets on cancer prevention and treatment. Emphasis will be placed on the role of insulin and IGF1 signaling in tumorigenesis as well as altered dietary needs of cancer patients.
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TL;DR: The association between dietary glycemic index (GI) and glycemic load (GL), markers of carbohydrate intake and PPG, and lung cancer risk in non-Hispanic whites suggests that dietary GI and other Lung cancer risk factors may jointly and independently influence lung cancer etiology.
Abstract: Background: Postprandial glucose (PPG) and insulin responses play a role in carcinogenesis. We evaluated the association between dietary glycemic index (GI) and glycemic load (GL), markers of carbohydrate intake and PPG, and lung cancer risk in non-Hispanic whites.
Methods: GL and GI were assessed among 1,905 newly diagnosed lung cancer cases recruited from the University of Texas MD Anderson Cancer Center (Houston, TX) and 2,413 healthy controls recruited at Kelsey-Seybold Clinics (Houston, TX). We assessed associations between quintiles of GI/GL and lung cancer risk and effect modification by various risk factors. ORs and 95% confidence intervals (CI) were estimated using multivariable logistic regression.
Results: We observed a significant association between GI [5th vs. 1st quintile (Q) OR = 1.49; 95% CI, 1.21–1.83; P trend <0.001] and lung cancer risk and GIac (5th vs. 1st Q OR = 1.48; 95% CI, 1.20–1.81; P trend = 0.001) and lung cancer risk. We observed a more pronounced association between GI and lung cancer risk among never smokers (5th vs. 1st Q OR = 2.25; 95% CI, 1.42–3.57), squamous cell carcinomas (SCC; 5th vs. 1st Q OR = 1.92; 95% CI, 1.30–2.83), and those with less than 12 years of education (5th vs. 1st Q OR = 1.75; 95% CI, 1.19–2.58, P interaction = 0.02).
Conclusion: This study suggests that dietary GI and other lung cancer risk factors may jointly and independently influence lung cancer etiology.
Impact: Understanding the role of GI in lung cancer could inform prevention strategies and elucidate biologic pathways related to lung cancer risk. Cancer Epidemiol Biomarkers Prev; 25(3); 532–9. ©2016 AACR .
36 citations
Cites background from "Is there a role for carbohydrate re..."
...Diets high in GI result in higher levels of blood glucose and insulin, which promote glucose intolerance, insulin resistance, and hyperinsulinemia (5, 6, 8)....
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...IGFs have been shown to play a critical role in regulating cell proliferation and differentiation in cancer (8) and there is evidence to suggest that IGFs are elevated in lung cancer patients (9, 10)....
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TL;DR: The objective is to test whether the ketogenic interventions are feasibly, as measured by the number of dropouts, and to see whether intervention groups 1 and 2 attain a better preservation of BIA phase angle than the control group.
Abstract: Summary Background We have found that a ketogenic diet (KD) during the course of radiotherapy (RT) was feasible and led to a preservation or favorable changes of body composition. Based on these observations and theoretical considerations, we initiated a study to investigate the impact of a KD or a ketogenic breakfast intervention in patients undergoing RT. Methods All patients presenting for curative RT with age between 18 and 75, body mass index between 18 and 34 kg/m 2 and a histologically confirmed cancer of the breast, colorectum or head and neck region are considered for inclusion. Exclusion criteria are Karnofsky index ® , vitaflo, Bad Homburg, Germany) plus (ii) 5–15 g amino acids (MAP, dr. reinwald healthcare gmbh+co kg, Schwarzenbruck, Germany). If willing to undertake a complete KD for the duration of RT, patients are entered into intervention group 2. Intervention group 2 does not have to fast prior to RT fractions but will be supplemented with MAP analogous to intervention group 1. The control group will not receive dietary advice to follow a KD or reduce carbohydrate intake. The objective is twofold: (i) to test whether the ketogenic interventions are feasibly, as measured by the number of dropouts; (ii) to see whether intervention groups 1 and 2 attain a better preservation of BIA phase angle than the control group. Endpoints Primary endpoints are the feasibility of the interventions (measured through dropout rates), and changes in body weight and composition (measured through BIA). Secondary endpoints are changes in quality of life (EORTC questionnaires) and blood parameters as well as the occurrence and grade of toxicities and grade of regression after surgery in case of colorectal carcinomas. Trial registration Registered under ClinicalTrials.gov Identifier no. NCT00123456 .
35 citations
Cites background from "Is there a role for carbohydrate re..."
...protect normal tissue from ionizing radiation [1,3]....
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...For example, inflammatory cytokines from the tumor tissue are able to promote insulin resistance, resulting in decreased glucose uptake in peripheral tissues, particularly skeletal muscle, and providing a rationale for a metabolically adapted diet with increased fat content for cancer patients [1,2]....
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TL;DR: High-quality evidence on the effect of ketogenic diets on anthropometry, metabolism, quality of life (QoL) and tumour effects is currently lacking in oncology patients, highlighting the need for controlled trials to fully evaluate the intervention.
Abstract: Background A growing body of evidence indicates the importance of nutrition in cancer treatment. Ketogenic diets are one strategy that has been proposed to enhance traditional anticancer therapy. This review summarises the evidence concerning the effect of oral ketogenic diets on anthropometry, metabolism, quality of life (QoL) and tumour effects, at the same time as documenting adverse events and adherence in patients with cancer. Methods We searched electronic databases using medical subject headings (MeSH) and text words related to ketogenic diets and cancer. Adult patients following a ketogenic diet as a complementary therapy prior, alongside or after standard anticancer treatment for more than 7 days were included. Studies were assessed for quality using the Critical Appraisal Skills Programme tools (https://www.casp-uk.net). Results Eleven studies were included with 102 participants (age range 34-87 years) from early-phase trials, cohort studies and case reports. Studies included participants with brain, rectal or mixed cancer sites at an early or advanced disease stage. The duration of intervention ranged from 2.4 to 134.7 weeks (0.5-31 months). Evidence was inconclusive for nutritional status and adverse events. Mixed results were observed for blood parameters, tumour effects and QoL. Adherence to diet was low (50 out of 102; 49%) and ranged from 23.5% to 100%. Conclusions High-quality evidence on the effect of ketogenic diets on anthropometry, metabolism, QoL and tumour effects is currently lacking in oncology patients. Heterogeneity between studies and low adherence to diet affects the current evidence. There is an obvious gap in the evidence, highlighting the need for controlled trials to fully evaluate the intervention.
35 citations
TL;DR: The results from the first case series in general practice suggest that it may be beneficial to advise tumour patients to adopt a ketogenic diet, and that those who adhere to it may have positive results from this type of diet.
Abstract: Since the initial observations by Warburg in 1924, it has become clear in recent years that tumour cells require a high level of glucose to proliferate. Therefore, a ketogenic diet that provides the body with energy mainly through fat and proteins, but contains a reduced amount of carbohydrates, has become a dietary option for supporting tumour treatment and has exhibited promising results. In the present study, the first case series of such a treatment in general practice is presented, in which 78 patients with tumours were treated within a time window of 10 months. The patients were monitored regarding their levels of transketolase-like-1 (TKTL1), a novel tumour marker associated with aerobic glycolysis of tumour cells, and the patients' degree of adherence to a ketogenic diet. Tumour progression was documented according to oncologists' reports. Tumour status was correlated with TKTL1 expression (Kruskal-Wallis test, P<0.0001), indicating that more progressed and aggressive tumours may require a higher level of aerobic glycolysis. In palliative patients, a clear trend was observed in patients who adhered strictly to a ketogenic diet, with one patient experiencing a stagnation in tumour progression and others an improvement in their condition. The adoption of a ketogenic diet was also observed to affect the levels of TKTL1 in those patients. In conclusion, the results from the present case series in general practice suggest that it may be beneficial to advise tumour patients to adopt a ketogenic diet, and that those who adhere to it may have positive results from this type of diet. Thus, the use of a ketogenic diet as a complementary treatment to tumour therapy must be further studied in rigorously controlled trials.
34 citations
Cites background from "Is there a role for carbohydrate re..."
...enough oxygen is present, which is not the case at those sites where the tumour grows rapidly (29,30)....
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TL;DR: It is found that a physiological level of 3-OHB can change the energetic profile of some BC cell lines, but there is no evidence that 3- OHB generally influences the biology of breast cancer cells in vitro.
Abstract: Ketogenic diets (KDs) or short-term fasting are popular trends amongst supportive approaches for cancer patients. Beta-hydroxybutyrate (3-OHB) is the main physiological ketone body, whose concentration can reach plasma levels of 2–6 mM during KDs or fasting. The impact of 3-OHB on the biology of tumor cells described so far is contradictory. Therefore, we investigated the effect of a physiological concentration of 3 mM 3-OHB on metabolism, proliferation, and viability of breast cancer (BC) cells in vitro. Seven different human BC cell lines (BT20, BT474, HBL100, MCF-7, MDA-MB 231, MDA-MB 468, and T47D) were cultured in medium with 5 mM glucose in the presence of 3 mM 3-OHB at mild hypoxia (5% oxygen) or normoxia (21% oxygen). Metabolic profiling was performed by quantification of the turnover of glucose, lactate, and 3-OHB and by Seahorse metabolic flux analysis. Expression of key enzymes of ketolysis as well as the main monocarboxylic acid transporter MCT2 and the glucose-transporter GLUT1 was analyzed by RT-qPCR and Western blotting. The effect of 3-OHB on short- and long-term cell proliferation as well as chemo- and radiosensitivity were also analyzed. 3-OHB significantly changed the oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) in BT20 cells resulting in a more oxidative energetic phenotype. MCF-7 and MDA-MB 468 cells had increased ECAR only in response to 3-OHB, while the other three cell types remained uninfluenced. All cells expressed MCT2 and GLUT1, thus being able to uptake the metabolites. The consumption of 3-OHB was not strongly linked to mRNA overexpression of key enzymes of ketolysis and did not correlate with lactate production and glucose consumption. Neither 3-OHB nor acetoacetate did interfere with proliferation. Further, 3-OHB incubation did not modify the response of the tested BC cell lines to chemotherapy or radiation. We found that a physiological level of 3-OHB can change the energetic profile of some BC cell lines. However, 3-OHB failed to influence different biologic processes in these cells, e.g., cell proliferation and the response to common breast cancer chemotherapy and radiotherapy. Thus, we have no evidence that 3-OHB generally influences the biology of breast cancer cells in vitro.
34 citations
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TL;DR: Recognition of the widespread applicability of these concepts will increasingly affect the development of new means to treat human cancer.
51,099 citations
"Is there a role for carbohydrate re..." refers background in this paper
..., a pathological capability common to most, if not all, cancer cells [39]....
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TL;DR: The molecular pathways of this cancer-related inflammation are now being unravelled, resulting in the identification of new target molecules that could lead to improved diagnosis and treatment.
Abstract: The mediators and cellular effectors of inflammation are important constituents of the local environment of tumours. In some types of cancer, inflammatory conditions are present before a malignant change occurs. Conversely, in other types of cancer, an oncogenic change induces an inflammatory microenvironment that promotes the development of tumours. Regardless of its origin, 'smouldering' inflammation in the tumour microenvironment has many tumour-promoting effects. It aids in the proliferation and survival of malignant cells, promotes angiogenesis and metastasis, subverts adaptive immune responses, and alters responses to hormones and chemotherapeutic agents. The molecular pathways of this cancer-related inflammation are now being unravelled, resulting in the identification of new target molecules that could lead to improved diagnosis and treatment.
9,282 citations
"Is there a role for carbohydrate re..." refers background in this paper
...Inflammation is a wellestablished driver of early tumorigenesis and accompanies most, if not all cancers [148]....
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TL;DR: In this article, the authors propose that persistent metabolism of glucose to lactate even in aerobic conditions is an adaptation to intermittent hypoxia in pre-malignant lesions, which leads to microenvironmental acidosis requiring evolution to phenotypes resistant to acid-induced cell toxicity.
Abstract: If carcinogenesis occurs by somatic evolution, then common components of the cancer phenotype result from active selection and must, therefore, confer a significant growth advantage. A near-universal property of primary and metastatic cancers is upregulation of glycolysis, resulting in increased glucose consumption, which can be observed with clinical tumour imaging. We propose that persistent metabolism of glucose to lactate even in aerobic conditions is an adaptation to intermittent hypoxia in pre-malignant lesions. However, upregulation of glycolysis leads to microenvironmental acidosis requiring evolution to phenotypes resistant to acid-induced cell toxicity. Subsequent cell populations with upregulated glycolysis and acid resistance have a powerful growth advantage, which promotes unconstrained proliferation and invasion.
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TL;DR: Dietary restriction and reduced activity of nutrient-sensing pathways may slow aging by similar mechanisms, which have been conserved during evolution, and their potential application to prevention of age-related disease and promotion of healthy aging in humans, and the challenge of possible negative side effects.
Abstract: When the food intake of organisms such as yeast and rodents is reduced (dietary restriction), they live longer than organisms fed a normal diet. A similar effect is seen when the activity of nutrient-sensing pathways is reduced by mutations or chemical inhibitors. In rodents, both dietary restriction and decreased nutrient-sensing pathway activity can lower the incidence of age-related loss of function and disease, including tumors and neurodegeneration. Dietary restriction also increases life span and protects against diabetes, cancer, and cardiovascular disease in rhesus monkeys, and in humans it causes changes that protect against these age-related pathologies. Tumors and diabetes are also uncommon in humans with mutations in the growth hormone receptor, and natural genetic variants in nutrient-sensing pathways are associated with increased human life span. Dietary restriction and reduced activity of nutrient-sensing pathways may thus slow aging by similar mechanisms, which have been conserved during evolution. We discuss these findings and their potential application to prevention of age-related disease and promotion of healthy aging in humans, and the challenge of possible negative side effects.
2,522 citations
"Is there a role for carbohydrate re..." refers background in this paper
...As indicated in Figure 2, restriction of dietary CHOs would counteract this signalling cascade by normalizing glucose and insulin levels in subjects with metabolic syndrome, in this way acting similar to calorie restriction/fasting [61,62]....
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