Dietary Supplements and Risk of Cause-Specific Death, Cardiovascular Disease, and Cancer: A Systematic Review and Meta-Analysis of Primary Prevention Trials

Non-Provitamin A and Provitamin A Carotenoids as Immunomodulators: Recommended Dietary Allowance, Therapeutic Index, or Personalized Nutrition?

Vegetables and fruits contain non-provitamin A (lycopene, lutein, and zeaxanthin) and provitamin A (β-carotene, β-cryptoxanthin, and α-carotene) carotenoids. Within these compounds, β-carotene has been extensively studied for its health benefits, but its supplementation at doses higher than recommended intakes induces adverse effects. β-Carotene is converted to retinoic acid (RA), a well-known immunomodulatory molecule. Human interventions suggest that β-carotene and lycopene at pharmacological doses affect immune functions after a depletion period of low carotenoid diet. However, these effects appear unrelated to carotenoids and retinol levels in plasma. Local production of RA in the gut-associated lymphoid tissue, as well as the dependency of RA-induced effects on local inflammation, suggests that personalized nutrition/supplementation should be considered in the future. On the other hand, the differential effect of RA and lycopene on transforming growth factor-beta suggests that lycopene supplementation could improve immune functions without increasing risk for cancers. However, such preclinical evidence must be confirmed in human interventions before any recommendations can be made.

The association between MTHFR polymorphism and cervical cancer

Cervical cancer is an extremely prevalent disease worldwide. The purpose of this study was to illustrate the relationship between methylenetetrahydrofolate reductase (MTHFR) polymorphisms or methionine synthase reductase (MTRR) polymorphisms and cervical cancer. There were 372 women who performed genetic and folic acid assessments. For the MTHFR C677T, there was no significant difference in the distribution of C allele and T allele in the three groups. However, the mutant C allele of MTHFR A1298C was significantly higher in the cancer group than in the normal group. Similarly, the mutant G allele of MTRR A66G was also higher than the normal group. The serum folic acid levels were gradually decreased with the development of cervical lesions. Serum folate levels in 4–9 ng/ml and ≤4 ng/ml were both significantly associated with cervical cancer risk. However, the MTHFR C677T polymorphism was not associated with the risk of cervical cancer or CIN. In contrast, the MTHFR A1298C polymorphism could increase the risk of both cervical cancer and CIN. In addition, the MTRR A66G polymorphism was only associated with the risk of cervical cancer but not CIN.

Recent novel approaches to limit oxidative stress and inflammation in diabetic complications

Diabetes is considered a major burden on the healthcare system of Western and non‐Western societies with the disease reaching epidemic proportions globally. Diabetic patients are highly susceptible to developing micro‐ and macrovascular complications, which contribute significantly to morbidity and mortality rates. Over the past decade, a plethora of research has demonstrated that oxidative stress and inflammation are intricately linked and significant drivers of these diabetic complications. Thus, the focus now has been towards specific mechanism‐based strategies that can target both oxidative stress and inflammatory pathways to improve the outcome of disease burden. This review will focus on the mechanisms that drive these diabetic complications and the feasibility of emerging new therapies to combat oxidative stress and inflammation in the diabetic milieu.

The effects of folate supplementation on glucose metabolism and risk of type 2 diabetes: a systematic review and meta-analysis of randomized controlled trials

PURPOSE

Observationally, homocysteine is associated with higher risk of diabetes. Folate, which reduces homocysteine, is promising for the prevention and treatment of diabetes. Previous meta-analysis of three trials suggested folate might lower hemoglobin A1c (HbA1c).

METHODS

An updated systematic review and meta-analysis of placebo-controlled randomized trials was conducted. We searched PubMed using ("folate" or "folic acid") and trial and ("glucose" or "diabetes" or "insulin" or "hemoglobin A1c" or "HbA1c") in any field until February 3, 2017. We also conducted a bibliographic search of selected studies and relevant reviews. Relative risk of diabetes and mean differences in indicators of glucose metabolism between folate and placebo were summarized in a meta-analysis using inverse variance weighting with random effects. Heterogeneity, publication bias, and risk of bias were also assessed.

RESULTS

Eighteen trials of 21,081 people with/without diabetes were identified. Folate decreased fasting glucose (-0.15 mmol/L, 95% confidence interval [CI] -0.29 to -0.01), homeostatic model assessment-insulin resistance (-0.83, 95% CI -1.31 to -0.34), and insulin (-1.94 μIU/mL, 95% CI -3.28 to -0.61) but had no clear effect on diabetes or HbA1c.

CONCLUSIONS

Our study suggests a potential benefit of folate on insulin resistance and glycemic control; the latter requires examination in more high-quality trials.

Selenium intake and metabolic syndrome: A systematic review

BACKGROUND & AIMS

Metabolic syndrome is a multi-causal disease. Its treatment includes lifestyle changes with a focus on weight loss. This systematic review assessed the association between Selenium intake and metabolic syndrome.

METHODS

Data were collected mainly from four databases: PubMed, CENTRAL (Cochrane), Scopus and Web of Knowledge. Keywords related to metabolic syndrome, selenium, as well as metabolic syndrome features were searched. This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement. A systematic review protocol was registered at PROSPERO (n. 42016046321). Two reviewers independently screened 2957 abstracts. Six studies were included to perform data extraction with standardized spreadsheets. The risk of bias was assessed by using specific tools according to the design of the relevant studies. An assessment was carried out based on the appropriateness of the study reports accordingly to STROBE and the CONSORT-based checklist for each study design.

RESULTS

Three studies found no association between Selenium intake and metabolic syndrome; two of them found an inverse association; and one study found a direct association between Selenium intake and metabolic syndrome. One study also showed an inverse association between Selenium intake and the prevalence of high waist circumference, high diastolic blood pressure, and hyperglycaemia in women.

CONCLUSIONS

Overall, based on the argumentation and results of this study, it is possible to conclude that Selenium intake and metabolic syndrome are not clearly associated in adults and elderly.

Habits and beliefs related to food supplements: Results of a survey among Italian students of different education fields and levels

The increasing availability of food supplements, aggressive media advertising, and common beliefs that these substances have only positive effects on health and sport performance indicate a need for continuous monitoring of this phenomenon. The aim of this study was to investigate the habits and beliefs related to diet supplementation among medical, health professional, and other university/high school students by means of a cross-sectional anonymous survey online. Among the respondents aware of supplements, 37.4% were taking or had taken them in the past. Food supplement use was more common among university students (in particular, those in health professional graduate courses) than high school students. Individual sport practice, rather than team sport, was associated with higher likelihood of food supplement use. Multivitamins were most commonly used, while weight-loss formulations were the least popular. Strikingly, filling nutrient gaps was statistically not considered the main reason for taking food supplements. Instead, they were used to enhance mental performance or enhance well-being. There was statistical evidence that students not enrolled in health or medical professional studies strongly agreed more often than medical students that taking food supplements prevents illness. These results indicate a striking difference between the evidence-based and personal reasons for food supplement use. Arguably, it calls for an improvement in education about diet supplementation and a change in attitude of health care providers to its implementation.

Serum selenium levels and the risk of progression of laryngeal cancer

Background

Observational studies have reported an inverse relationship between selenium status (blood or toenail) and the risk of laryngeal cancer; however, the impact of low serum selenium level on survival has not been evaluated.

Methods

We conducted a prospective study of 296 patients diagnosed with laryngeal cancer in Szczecin, Poland. Serum selenium was measured at diagnosis and prior to treatment. Patients were followed from the date of diagnosis to death at five years. Vital status was obtained by linkage to the Polish National Death Registry.

Results

The five-year survival after diagnosis was 82.0% (95% CI: 68% to 91%) for individuals in the highest quartile of serum selenium (> 66.8 μg/L) and was 28.6% (95% CI 19% to 42%) for individuals in the lowest quartile (<50.0 μg/L). In an age- and sex-adjusted analysis, the hazard ratio (HR) for death from all causes was 7.01 (95% CI 3.81 to 12.9) for patients in the lowest quartile of serum selenium, compared to those in the highest quartile. The corresponding multivariate HR was 3.07 (95% CI 1.59 to 5.94).

Conclusions

This study suggests that a selenium level in excess of 70 μg/L is associated with improved outcome among patients undergoing treatment for laryngeal cancer. Further studies are needed to evaluate if selenium supplementation to achieve this level might improve overall prognosis.

Antioxidant intake from diet and supplements and risk of digestive cancers in middle-aged adults: results from the prospective NutriNet-Santé cohort

Experimental studies suggest beneficial effects of antioxidants in digestive cancer prevention. However, epidemiological results are contrasting and few studies quantitatively assessed supplemental intake. This study aimed at investigating the associations between antioxidant intakes (dietary, supplemental and total) and digestive cancer risk. This prospective study included 38 812 middle-aged subjects (≥45 years) from the NutriNet-Santé cohort (2009-2016). Dietary data were collected using repeated 24 h records. A specific questionnaire assessed dietary supplement use over a 12-month period. A composition database of about 8000 dietary supplements was developed. Associations between continuous and sex-specific quartiles of vitamins C and E, β-carotene and Se intakes and digestive cancer risk were characterised using multivariable Cox proportional hazard models. A total of 167 incident digestive cancers (120 colorectal, twenty-six pancreatic, nine oesophagus, seven stomach and five liver) were diagnosed during follow-up investigation. Dietary (hazard ratios (HR)Q4 v. Q1=0·56; 95 % CI 0·34, 0·91, P trend=0·01) and total (HRQ4 v. Q1=0·51; 95 % CI 0·30, 0·84, P trend=0·008) vitamin C intakes, dietary (HRQ4 v. Q1=0·56; 95 % CI 0·34, 0·92, P trend=0·005) and total (HRQ4 v. Q1=0·58; 95 % CI 0·36, 0·94, P trend=0·003) vitamin E intakes, and dietary (HRfor an increment of 10 µg/d=0·92; 95 % CI 0·85, 1·00, P=0·04) and total (HRfor an increment of 10 µg/d=0·92; 95 % CI 0·86, 0·99, P=0·03) Se intakes were associated with a decreased digestive cancer risk. Statistically significant interactions were observed between dietary and total Se intakes and alcohol consumption as well as between total vitamin E intake and smoking status. This prospective cohort study with quantitative assessment of supplemental intakes suggests a potential protective effect of several antioxidants (vitamins C and E and Se) on digestive cancer risk, and a modulation of some of these relationships by alcohol consumption and smoking status.

A Heart-Healthy Diet: Recent Insights and Practical Recommendations

PURPOSE OF REVIEW

The purpose of this study is to review the current evidence on the relationship between diet and heart, giving practical recommendations for cardiovascular prevention.

RECENT FINDINGS

A heart-healthy diet should maximize the consumption of whole grains, vegetables, fruit, and legumes and discourage the consumption of meat and meat products as well as refined and processed foods. Plant-based diets fully meet these criteria, and the evidence supporting the protective effect of these dietary patterns evolved rapidly in recent years. Among plant-based diets, the Mediterranean and vegetarian diets gained the greater interest, having been associated with numerous health benefits such as reduced levels of traditional and novel risk factors and lower risk of cardiovascular disease. These positive effects may be explained by their high content of dietary fiber, complex carbohydrate, vitamins, minerals, polyunsaturated fatty acids, and phytochemicals. Current evidence suggests that both Mediterranean and vegetarian diets are consistently beneficial with respect to cardiovascular disease.

Recommendations of the Spanish Menopause Society on the consumption of omega-3 polyunsaturated fatty acids by postmenopausal women

The consumption of long-chain omega-3 polyunsaturated fatty acids (LCO3-PUFAs) has shown a great variety of beneficial effects, including cardiovascular, metabolic and inflammatory effects, which make them interesting for the postmenopausal woman. Because LCO3-PUFAs could be effective and safe during this period, a panel of experts from the Spanish Menopause Society met to establish a set of recommendations for their use in postmenopausal women based on the best available evidence. The decrease in triglycerides is the most consistent effect observed with LCO3-PUFAs (at doses greater than 3g/day). In addition, LCO3-PUFAs have antiarrhythmic effects, reduce blood pressure, improve depressive and psychotic symptoms, and do not increase the risk of cancer. However, further studies are needed to confirm the benefit of LCO3-PUFAs in the relief of menopause symptoms and osteoporosis.