No effect of caloric restriction or exercise on radiation repair capacity

Clinical implications of nutritional interventions reducing calories, a systematic scoping review

BACKGROUND & AIMS

Caloric restriction (CR) constitutes a dietary approach of (temporarily) reducing calorie intake thereby inducing resilience and resistance mechanisms and promoting health. While CR's feasibility and safety have been proven in human trials, its full benefits and translation to different study populations warrants further exploration.

METHODS

We here conducted a systematic scoping review adhering to Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines.

RESULTS

Our search resulted in 3745 individual records, of which 40 were included. We showed that all studies consistently demonstrated the feasibility and safety of CR-like interventions. The specific effects of nutritional preconditioning vary, further underscoring the need for carefully crafted strategies, according to the intended effect, patient population, and logistical limitations.

CONCLUSIONS

CR-like interventions (long-term CR or short-term fasting) are feasible in a broad range of patient populations. Whether it has clinical benefit, f.i. reducing treatment-induced side effects and enhancing therapy efficacy, has to be investigated further.

Use of the Single Cell Gel Electrophoresis Assay for the Detection of DNA-protective Dietary Factors: Results of Human Intervention Studies

The single cell gel electrophoresis technique is based on the measurement of DNA migration in an electric field and enables to investigate via determination of DNA-damage the impact of foods and their constituents on the genetic stability. DNA-damage leads to adverse effects including cancer, neurodegenerative disorders and infertility. In the last 25 years approximately 90 human intervention trials have been published in which DNA-damage, formation of oxidized bases, alterations of the sensitivity towards reactive oxygen species and chemicals and of repair functions were investigated with this technique. In approximately 50% of the studies protective effects were observed. Pronounced protection was found with certain plant foods (spinach, kiwi fruits, onions), coffee, green tea, honey and olive oil. Also diets with increased contents of vegetables caused positive effects. Small amounts of certain phenolics (gallic acid, xanthohumol) prevented oxidative damage of DNA; with antioxidant vitamins and cholecalciferol protective effects were only detected after intake of doses that exceed the recommended daily uptake values. The evaluation of the quality of the studies showed that many have methodological shortcomings (lack of controls, no calibration of repair enzymes, inadequate control of the compliance and statistical analyses) which should be avoided in future investigations.

Impact of Bariatric Surgery on the Stability of the Genetic Material, Oxidation, and Repair of DNA and Telomere Lengths

Obesity causes genetic instability, which plays a key-role in the etiology of cancer and aging. We investigated the impact of bariatric surgery (BS) on DNA repair, oxidative DNA damage, telomere lengths, alterations of antioxidant enzymes and, selected proteins which reflect inflammation. The study was realized with BS patients (n = 35). DNA damage, base oxidation, BER, and NER were measured before and 1 month and 6 months after surgery with the single-cell gel electrophoresis technique. SOD and GPx were quantified spectrophotometrically, malondealdehyde (MDA) was quantified by HPLC. Telomere lengths were determined with qPCR, and plasma proteome profiling was performed with high-resolution mass spectrophotometry. Six months after the operations, reduction of body weight by 27.5% was observed. DNA damage decreased after this period, this effect was paralleled by reduced formation of oxidized DNA bases, a decline in the MDA levels and of BER and NER, and an increase in the telomere lengths. The activities of antioxidant enzymes were not altered. Clear downregulation of certain proteins (CRP, SAA1) which reflect inflammation and cancer risks was observed. Our findings show that BS causes reduced oxidative damage of DNA bases, possibly as a consequence of reduction of inflammation and lipid peroxidation, and indicate that the surgery has beneficial long-term health effects.

Association between DNA repair capacity and body mass index in women

OBJECTIVE

Examine whether DNA repair capacity (DRC) levels are associated with body mass index (BMI) in adult women.

DESIGN AND PARTICIPANTS

A nested study composed of 539 women without breast cancer (BC) from a case-control BC study in addition to 104 that were recruited later for a total of 643.

MEASUREMENTS

DRC levels were measured in lymphocytes using a host-cell reactivation assay with a luciferase reporter gene damaged by UVC. This assay measures the efficiency of nucleotide excision repair (NER). Log-binomial regression model was used. The prevalence ratio (PR) was used to evaluate the magnitude of the association between the BMI and DRC levels. An assessment of interaction terms was performed with the likelihood ratio test. The confounding effect was assessed by comparing the point estimates of the crude and adjusted PR.

RESULTS

The 75th percentiles of DRC levels of the women with a BMI between 18 and 25 and > 25 showed statistically significant differences. The prevalence of a DRC ≤ 5 % among women with BMI > 25 is 1.24 (95 % CI: 1.03, 1.48) times the prevalence of having a DRC ≤ 5 % among the women with BMI ≤ 25 after adjustments for different covariates. This excess was statistically significant (p < 0.05). Women with a family history of cancer had an estimated PR of 1.25 (95 % CI, 0.87-1.39; P ≥ 0.05); and women with no family history of cancer, the estimated PR was 1.6 (95 % CI, 1.14-2.22; p ≤ 0.05).

CONCLUSIONS

Women with BMI > 25 tend to have lower DRC levels. When having a family history of cancer, the PR of low DRC levels in overweight/obese individuals was not statistically significant. However, the PR of low levels of DRC in overweight/obese individuals with no family history of cancer was statistically significant.

Calorie restriction and breast cancer treatment: a mini-review

Calorie restriction (CR), referred to as a reduction in dietary calorie intake without malnutrition, has been demonstrated to be a safe way to extend longevity of yeast, worms, and laboratory animals, and to decrease the risk factors in age-related diseases including cancer in humans. Pre-clinical studies in animal models demonstrated that CR may enhance the efficacy of chemotherapy, radiation therapy, and immunotherapy during breast cancer treatment. Reduced calorie intake ameliorates risk factors and delays the onset of cancer by altering metabolism and fostering health-enhancing characteristics including increased autophagy and insulin sensitivity, and decreased blood glucose levels, inflammation, angiogenesis, and growth factor signaling. CR is not a common protocol implemented by medical practitioners to the general public due to the lack of substantial clinical studies. Future research and clinical trials are urgently needed to understand fully the biochemical basis of CR or CR mimetics to support its benefits. Here, we present a mini-review of research studies integrating CR as an adjuvant to chemotherapy, radiation therapy, or immunotherapy during breast cancer treatment.

Changes in anthropometric, biochemical, oxidative, and DNA damage parameters after 3-weeks-567-kcal-hospital-controlled-VLCD in severely obese patients with BMI ≥ 35 kg m-2

BACKGROUND & AIMS

Severe obesity and its comorbidities relate to increased genomic instability/cancer risk. Obesity in Croatia is rapidly increasing, and long diets are sometimes the reason for obese to quit health improvement programs. A shorter diet with more strict calorie reduction could also lead to weight reduction and health improvements, but data are scarce. We tested for the first time if a very low-calorie diet (VLCD) can improve anthropometric, biochemical and genomic stability parameters in severely obese with BMI ≥ 35 kg m^-2.

METHODS

22 participants were chosen among those regularly attending the hospital for obesity control, with no other previous treatment for bodyweight reduction. Under 24 h medical surveillance, patients received 3-weeks-567-kcal-hospital-controlled-VLCD composed of 50-60% complex carbohydrates, 20-25% proteins, and 25-30% fat, with the attention to food carbo-glycemic index, in 3 meals freshly prepared in hospital. We analyzed changes in body weight, BMI, basal metabolism rate, waist-hip ratio, visceral fat level, body fat mass, percent body fat, skeletal muscle mass, basal metabolism, energy intake, lipid profile, thyroid hormones, TSH, and genomic instability (alkaline and oxidative FPG comet assay) before and on the last VLCD day.

RESULTS

Diet caused BMI reduction (in average 3-4 BMI units' loss), excessive weight loss (between 10 and 35%), significant weight loss (average 9 kg, range 4.8-14.4 kg) and a significant decrease in glucose, insulin, urea, cholesterol, HDL-c, LDL-c, oxidative (FPG) and DNA damage (alkaline comet assay) levels.

CONCLUSIONS

The diet can lead to ≥10% excessive weight loss, significant health, and genomic stability improvement, and keep severely obese interest in maintaining healthy habits. The study was registered at ClinicalTrials.gov as NCT05007171 (10.08.2021).

Type and Intensity as Key Variable of Exercise in Metainflammation diseases: A Review

Monocyte and lymphocyte subpopulations exhibit functions that vary between the anti- and pro-inflammatory spectrum, such as classic CD16- and non-classical CD16+ monocytes, as well as T helper 2 lymphocytes (Th2), the Th1/Th17 lymphocytes ratio, and T regulatory lymphocytes (Treg). Metabolic disease-associated inflammation is accompanied by an imbalance in monocyte and lymphocyte phenotypes and functionality, as well as a stronger proportion of inflammatory subpopulations. These changes appear to be important for the development and progression of diseases like diabetes and cardiovascular disease. On the other hand, the regular practice of physical exercise is an important tool to restore the functionality of monocytes and lymphocytes, and to balance the subtypes ratio. However, key variables regarding exercise prescription, such as the type of exercise, intensity, and volume differentially impact on the acute and chronic immune response in individuals diagnosed with meta inflammation diseases. Here, we discuss the impact of different physical exercise protocols, acutely and chronically, on monocytes and lymphocytes of individuals with metabolic disease-associated inflammation. In this review, we focus on the best effects of different exercise protocols to dose the "exercise pill" in different inflammatory status.

Collection and storage of human white blood cells for analysis of DNA damage and repair activity using the comet assay in molecular epidemiology studies

DNA damage and repair activity are often assessed in blood samples from humans in different types of molecular epidemiology studies. However, it is not always feasible to analyse the samples on the day of collection without any type of storage. For instance, certain studies use repeated sampling of cells from the same subject or samples from different subjects collected at different time-points, and it is desirable to analyse all these samples in the same comet assay experiment. In addition, flawless comet assay analyses on frozen samples open up the possibility of using this technique on biobank material. In this article we discuss the use of cryopreserved peripheral blood mononuclear cells (PBMCs), buffy coat (BC) and whole blood (WB) for analysis of DNA damage and repair using the comet assay. The published literature and the authors' experiences indicate that various types of blood samples can be cryopreserved with only a minor effect on the basal level of DNA damage. There is evidence to suggest that WB and PBMCs can be cryopreserved for several years without much effect on the level of DNA damage. However, care should be taken when cryopreserving WB and BCs. It is possible to use either fresh or frozen samples of blood cells, but results from fresh and frozen cells should not be used in the same dataset. The article outlines detailed protocols for the cryopreservation of PBMCs, BCs and WB samples.

The Potential of Fasting and Caloric Restriction to Mitigate Radiation Damage-A Systematic Review

Detrimental health effects from ionizing radiation to living organisms is one of the key concerns identified and addressed by Radiation Protection institutions, nationally and internationally on Earth and for human spaceflight. Thus, new methods for mitigating the adverse effects of ionizing radiation are urgently needed for terrestrial health and deep space exploration. Caloric restriction and (intermittent-) fasting have been reported to elicit a variety of immediate and long-term physiological effects. The rapidly growing body of evidence of research studies investigating the effects of caloric restriction and dietary fasting points toward a multitude of benefits affecting numerous physiological systems. Therefore, a systematic review was performed to evaluate the evidence of caloric restriction and dietary fasting on the physiological response to ionizing radiation in humans and animals. All experimental studies of humans, animals, and eukaryotic cell lines available in PubMed, Cochrane library, and specialized databases were searched comparing irradiation post-caloric restriction or fasting to a non-nutritionally restricted control group on a broad range of outcomes from molecular to clinical responses. The initial search yielded 2,653 records. The final analysis included 11 studies. Most studies investigated survival rate or cancer occurrence in animals. Included studies did not reveal any benefit from pre exposure caloric restriction, except when performed with post radiation caloric restriction. However, the effects of pre-exposure fasting suggest increased resilience to ionizing radiation.

Smoking index, lifestyle factors, and genomic instability assessed by single-cell gel electrophoresis: a cross-sectional study in subjects from Yucatan, Mexico

BACKGROUND

It is widely accepted that genomic instability is associated with several mechanisms involving oxidative stress, which can increase the rate of DNA breaks. Such factors include smoking, impairments in body composition, an unhealthy lifestyle, and a hereditary history of cancer. The aim was to evaluate the degree of association of genomic instability in smokers and non-smokers, and how the risk could change depending on the lifestyle and other causes. For this purpose, a survey of tobacco consumption, dietary patterns, physical activity, antecedents of cancer, and body composition assessment was carried out. Genomic instability was evaluated through a single-cell gel electrophoresis using peripheral blood mononuclear cells in three different conditions of oxidative stress. The analysis of genomic damage degree was performed through a dimension reduction procedure (principal component analysis) from 16 parameters per treatment (adding up 48 parameters of genomic damage per subject) and a binary logistic regression model for DNA fragmentation risk.

RESULTS

The sample consisted of 82 participants, divided into three age groups: young adults (18-35 years), adults (36-59 years), and older adults (60-95 years). As expected, the results showed a significant positive correlation of age with genomic damage rates, represented by 2 PCA groups (p = 0.027, p = 0.004). There were consistent significant positive associations of genomic damage rates with smoking index and three PCA groups (p = 0.007, p = 0.004, p = 0.009). The smoking status and age group analysis revealed that there were significant differences for adult smokers with the same aforementioned PCA groups (p = 0.002, p = 0.001, p = 0.010). In addition, higher DNA damage rates were found in subjects with incorrect diet patterns, long sitting hours, and previous exposure to radiation. The analysis with binary logistic regression displayed two models in which lifestyles (age, diet, and/or sedentarism) did not change the significance of smoking index for DNA fragmentation risk; however, when physical activity was present in the model, the smoking index was not a significant factor for DNA damage risk.

CONCLUSIONS

Although it is well known that smoking affects human health in different ways, DNA fragmentation can be analyzed by a damage phenotypic analysis and integrate a risk analysis reshaped by diet and lifestyle in general.

The weight of obesity in breast cancer progression and metastasis: Clinical and molecular perspectives

The escalating epidemic of overweight and obesity is currently recognized as one of the most significant health and economic concern worldwide. At the present time, over 1.9 billion adults and more than 600 million people can be, respectively, classified as overweight or obese, and numbers will continue to increase in the coming decades. This alarming scenario implies important clinical implications since excessive adiposity can progressively cause and/or exacerbate a wide spectrum of co-morbidities, including type 2 diabetes mellitus, hypertension, cardiovascular disease, and even certain types of cancer, including breast cancer. Indeed, pathological remodelling of white adipose tissue and increased levels of fat-specific cytokines (mainly leptin), as a consequence of the obesity condition, have been associated with several hallmarks of breast cancer, such as sustained proliferative signaling, cellular energetics, inflammation, angiogenesis, activating invasion and metastasis. Different preclinical and clinical data have provided evidence indicating that obesity may worsen the incidence, the severity, and the mortality of breast cancer. In the present review, we will discuss the epidemiological connection between obesity and breast cancer progression and metastasis and we will highlight the candidate players involved in this dangerous relationship. Since the major cause of death from cancer is due to widespread metastases, understanding these complex mechanisms will provide insights for establishing new therapeutic interventions to prevent/blunt the effects of obesity and thwart breast tumor progression and metastatic growth.

Obesity, Leptin and Breast Cancer: Epidemiological Evidence and Proposed Mechanisms

The prevalence of obesity has been steadily increasing over the past few decades in several developed and developing countries, with resultant hazardous health implications. Substantial epidemiological evidence has shown that excessive adiposity strongly influences risk, prognosis, and progression of various malignancies, including breast cancer. Indeed, it is now well recognized that obesity is a complex physiologic state associated with multiple molecular changes capable of modulating the behavior of breast tumor cells as well of the surrounding microenvironment. Particularly, insulin resistance, hyperactivation of insulin-like growth factor pathways, and increased levels of estrogen due to aromatization by the adipose tissue, inflammatory cytokines, and adipokines contribute to breast cancerogenesis. Among adipokines, leptin, whose circulating levels increase proportionally to total adipose tissue mass, has been identified as a key member of the molecular network in obesity. This review summarizes the current knowledge on the epidemiological link existing between obesity and breast cancer and outlines the molecular mechanisms underlying this connection. The multifaceted role of the obesity adipokine leptin in this respect is also discussed.

Reduction of DNA damage in peripheral lymphocytes of obese patients after bariatric surgery-mediated weight loss

Obesity is associated with several detrimental health consequences, among them an increased risk for development of cancer, and an overall elevated mortality. Multiple factors like hyperinsulinemia, chronic microinflammation and oxidative stress may be involved. The comet assay has been proven to be very sensitive for detection of DNA damage and has been used to explore the relationship between overweight/obesity and DNA damage, but results are controversial. Very few investigations have been performed to correlate weight loss of obese individuals and possible reduction of DNA damage and these studies have not provided clear results. As currently, only surgical interventions (metabolic/bariatric surgery) enable substantial and sustained weight loss in the vast majority of morbidly obese patients, we analyzed whole blood samples of 56 subsequent patients prior, 6 and 12 months after bariatric surgery. No reduction of DNA damage was observed in comet assay analysis after 6 months despite efficient weight loss, but a significant reduction was observed 12 months after surgery. Concurrently, the ferric-reducing antioxidant power assay showed a significant reduction after 6 and 12 months. The level of oxidised glutathione and lipid peroxidation products were increased at 6 months but normalised at 12 months after surgery. As conclusion, a significant weight reduction in obese patients may help to diminish existing DNA damage besides improving many other health aspects in these patients.

Energy balance and gastrointestinal cancer: risk, interventions, outcomes and mechanisms

Obesity increases the risk of multiple gastrointestinal cancers and worsens disease outcomes. Conversely, strong inverse associations have emerged between physical activity and colon cancer and possibly other gastrointestinal malignancies. The effect of weight loss interventions - such as modifications of diet and/or physical activity or bariatric surgery - remains unclear in patients who are obese and have gastrointestinal cancer, although large clinical trials are underway. Human intervention studies have already shed light on potential mechanisms underlying the energy balance-cancer relationship, with preclinical models supporting emerging pathway effects. Central to interventions that reduce obesity or increase physical activity are pluripotent cancer-preventive effects (including reduced systemic and adipose tissue inflammation and angiogenesis, altered adipokine levels and improved insulin resistance) that directly interface with the hallmarks of cancer. Other mechanisms, such as DNA repair, oxidative stress and telomere length, immune function, effects on cancer stem cells and the microbiome, could also contribute to energy balance effects on gastrointestinal cancers. Although some mechanisms are well understood (for instance, systemic effects on inflammation and insulin signalling), other areas remain unclear. The current state of knowledge supports the need to better integrate mechanistic approaches with preclinical and human studies to develop effective, personalized diet and exercise interventions to reduce the burden of obesity on gastrointestinal cancer.

Effects of Intentional Weight Loss on Markers of Oxidative Stress, DNA Repair and Telomere Length - a Systematic Review

BACKGROUND

Altered levels of markers of oxidative stress, DNA repair, and telomere integrity have been detected in obese individuals and may underlie the pathogenesis of obesity-related diseases. However, whether or not such effects are reversed by intentional weight loss has not been systematically reviewed.

METHODS

A literature search in PubMed/Medline identified 2,388 articles of which 21 studies (randomized controlled trial (RCT) (n = 10) and non-randomized intervention studies (n = 11)) were classified as testing the effects of intentional weight loss on i) oxidative stress (n = 15), ii) DNA repair (n = 2), and iii) telomere length (n = 4).

RESULTS

Across a broad range of intervention designs, diet-, exercise-, surgery-, balloon-induced weight loss regimens decreased oxidative stress measures. Studies investigating DNA repair capacity or telomere length as endpoints after weight loss were less common in number and yielded null or inconsistent results, respectively.

CONCLUSION

While this systematic review supports a role for intentional weight loss in reducing obesity-associated oxidative stress, it is not clear whether the effects are primary outcomes or secondary to improvement in obesity-associated insulin resistance and/or chronic inflammation. Although the lack of effect of intentional weight loss on DNA repair capacity might be anticipated given that oxidative stress is reduced, additional studies are needed. The inconsistent effects of weight loss on telomere length or DNA repair suggest the need for a re-assessment of intervention designs and assay methodology to definitively address this topic.

Use of Single-cell Gel Electrophoresis Assays in Dietary Intervention Trials

The single-cell gel electrophoresis (SCGE) technique has been frequently used to investigate the impact of consumption of complex foods and individual constituents on DNA stability in humans. Since no division or cultivation of the indicator cells (in most studies lymphocytes) is required, this approach is less costly and time consuming than cytogenetic methods. Apart from single- and double-stand breaks and apurinic sites, which can be detected under standard conditions, it is also possible to assess the formation of oxidized DNA bases and alterations of DNA repair as well as protection of the DNA against chemical carcinogens. In total, 93 studies have been published since the first use of the Comet assay in this field in 1997. The results which emerged from these studies show that human foods contain specific highly protective components (e.g. gallic acid, xanthohumol, isoflavones); promising results were also obtained with beverages (coffee and other drinks), while mixed diets with vegetables and fruits conferred no or moderate protection; however, individual plant foods (e.g. kiwis and specific cruciferous vegetables) were highly protective. It is notable that prevention of DNA damage was rarely detected under standard conditions while evidence for reduced formation of oxidized DNA bases was found in approximately 30% of the trials. In some investigations it was possible to identify the modes of action by which specific compounds prevented damage of the genetic material in additional mechanistic experiments. The currently available data show that SCGE assays are a valuable tool for identifying dietary factors which improve the stability of the genetic material and prevent adverse health effects which are causally related to DNA damage.