Context
Vitamin D deficiency is considered a global public health issue, even in low-latitude countries where there is abundant sunlight radiation. Nevertheless, the prevalence of vitamin D insufficiency and deficiency in the South American continent has not been well characterized.
Objective
The aim of this review was to estimate the prevalence of vitamin D deficiency (25-hydroxy-calciferol < 20 ng/mL) in South American populations.
Data Sources
Seven electronic databases (MEDLINE, Web of Science, Embase, Biblioteca Virtual de Saúde, SciELO, Scopus, and Google Scholar) were searched systematically for observational studies published before July 1, 2021, and reporting vitamin D status of healthy adults in South America.
Data Extraction
Data were extracted using a standardized form. Risk of bias was assessed by the Joanna Briggs Institute Critical Appraisal Instrument for Studies Reporting Prevalence. All steps were conducted independently by two authors. Data were pooled using a random-effects model. Stratified meta-analysis and meta-regression were conducted (R software).
Data Analysis
Of 9460 articles identified, 96 studies with a total of 227 758 participants were included. The overall prevalence of vitamin D deficiency was 34.76% (79 studies; 95%CI, 29.68–40.21; I2 = 99%). There were significant differences in prevalence rates related to age, sex, country, latitude, season, and year of publication.
Conclusion
The prevalence of vitamin D deficiency is unexpectedly elevated in South American populations. Public health strategies should include efforts to prevent, detect, and treat vitamin D deficiency.
Systematic Review Registration
PROSPERO registration number CRD42020169439.
The beet, including the leaves and stalk (BLS), is a vegetable with great antioxidant potential. The aim of this study was to evaluate the differences in the nutritional composition and the concentration of total phenolics between the organic and conventional BLS and to verify whether the ingestion of an organic BLS juice containing different concentrations of polyphenols modulated some biomarkers of oxidative stress after the ingestion of a high-fat meal in individuals with dyslipidemia. A controlled, randomized, double-blind, crossover clinical trial with a washout period of 1 week was carried out. A 12-h fasting blood sample was collected. Afterward, the participants consumed a high-fat meal, followed by the ingestion of a placebo or one of the organic BLS juices containing either 32.0 or 77.5 mg/100 mL of polyphenols. Blood samples were obtained 30, 60, 120 and 180 min after the first blood collection. The composition analysis showed that organic BLS had a better nutritional composition than conventional ones. The high-fat meal induced postprandial hypertriglyceridemia after 120 min (p < 0.001) and increased the concentration of malondialdehyde after 30 min (p < 0.001). In addition, there was a significant increase in GPx in 30 min (p = 0.026). This increase was attenuated in the group that received the highest dose of polyphenols when compared with the placebo after 30 min (p = 0.045). Therefore, the organic BLS juice containing 77.5 mg of polyphenols was efficient at modulating one of the postprandial mechanisms of enzymatic antioxidant protection in individuals with dyslipidemia.
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