Browsing by Subject "BETA-CAROTENE"

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  • Hemilä, Harri (2007)
  • Tainio, Karoliina; Athanasiou, Antonios; Tikkinen, Kari A. O.; Aaltonen, Riikka; Cardenas Hernandes, Jovita; Glazer-Livson, Sivan; Jakobsson, Maija; Joronen, Kirsi; Kiviharju, Mari; Louvanto, Karolina; Oksjoki, Sanna; Tähtinen, Riikka; Virtanen, Seppo; Nieminen, Pekka; Kyrgiou, Maria; Kalliala, Ilkka (2018)
    OBJECTIVE To estimate the regression, persistence, and progression of untreated cervical intraepithelial neoplasia grade 2 (CIN2) lesions managed conservatively as well as compliance with follow-up protocols. DESIGN Systematic review and meta-analysis. DATA SOURCES Medline, Embase, and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) from 1 January 1973 to 20 August 2016. ELIGIBILITY CRITERIA Studies reporting on outcomes of histologically confirmed CIN2 in non-pregnant women, managed conservatively for three or more months. DATA SYNTHESIS Two reviewers extracted data and assessed risk of bias. Random effects model was used to calculate pooled proportions for each outcome, and heterogeneity was assessed using I-2 statistics. MAIN OUTCOME MEASURES Rates of regression, persistence, or progression of CIN2 and default rates at different follow-up time points (3, 6, 12, 24, 36, and 60 months). RESULTS 36 studies that included 3160 women were identified (seven randomised trials, 16 prospective cohorts, and 13 retrospective cohorts; 50% of the studies were at low risk of bias). At 24 months, the pooled rates were 50% (11 studies, 819/1470 women, 95% confidence interval 43% to 57%; I-2= 77%) for regression, 32% (eight studies, 334/1257 women, 23% to 42%; I-2= 82%) for persistence, and 18% (nine studies, 282/1445 women, 11% to 27%; I-2= 90%) for progression. In a subgroup analysis including 1069 women aged less than 30 years, the rates were 60% (four studies, 638/1069 women, 57% to 63%; I-2= 0%), 23% (two studies, 226/938 women, 20% to 26%; I-2= 97%), and 11% (three studies, 163/1033 women, 5% to 19%; I-2= 67%), respectively. The rate of non-compliance (at six to 24 months of follow-up) in prospective studies was around 10%. CONCLUSIONS Most CIN2 lesions, particularly in young women (<30 years), regress spontaneously. Active surveillance, rather than immediate intervention, is therefore justified, especially among young women who are likely to adhere to monitoring.
  • Hemilä, Harri; Virtamo, Jarmo; Albanes, Demetrius; Kaprio, Jaakko (2006)
  • Hemilä, Harri (2007)
    Moreira et al (2007) systematically reviewed the role of nutrition on exercise-induced immunodepression. However, their paper has several shortcomings. Moreira refers to Nieman’s ‘J’-curve hypothesis, which proposes that moderate exercise improves the immune system and reduces the risk of upper respiratory tract infections (URI), whereas excessive physical stress impairs the immune system and increases URI risk (Nieman, 1994). In a large cohort, we found that the risk of the common cold and pneumonia was not reduced with moderate physical activity, refuting the universal validity of the ‘J’-model (Hemila et al, 2003, 2006). There is strong evidence of positive effect of vitamin C on physically stressed people and there is no valid evidence that vitamin C would be harmful to ordinary people in doses of 1–2 g/day. Therefore, physically active people, who consider that they suffer from colds frequently, can use vitamin C, while at the same time, we hope that new trials would be carried out.
  • Hemila, Harri (2016)
    Background: Vitamin E has influenced the immune system in laboratory studies. Dozens of animal experiments have found that vitamin E offered protection against infections caused by viruses and bacteria. Previously, significant heterogeneity was found in the effect of vitamin E supplementation on pneumonia in humans. The aim of this study was to examine how the effect of vitamin E on pneumonia risk depends on age. Methods: Secondary analysis of the Alpha-Tocopherol, Beta-Carotene Cancer Prevention study in Finland, 1985-1993, was performed. Participants were male smokers aged 50-69 years at the baseline who started to smoke at >= 21 years (N=7,469). Intervention was 50 mg/d of vitamin E for 5-8 years. The outcome was the incidence of hospital-treated, community-acquired pneumonia by the age at the follow-up. Results: Among 2,216 participants who smoked 5-19 cigarettes per day at baseline and exercised at leisure time, vitamin E supplementation reduced the incidence of pneumonia by 69% (95% confidence interval [CI]: 43%-83%; 57 pneumonia cases). In this subgroup, vitamin E prevented pneumonia in 12.9% of participants by the age of 74 years. Among 5,253 participants who smoked >= 20 cigarettes per day at baseline or did not exercise, the incidence of pneumonia was 14% lower in the vitamin E participants (95% CI: -38% to +21%; 139 cases). One-third of the participants quit smoking for a period, of whom 27 got pneumonia. The incidence of pneumonia was 72% (95% CI: 31%-89%) lower in the vitamin E group, and this benefit was also seen among those males who smoked >20 cigarettes per day at baseline or did not exercise. Conclusion: Although the evidence of benefit from vitamin E against pneumonia in elderly males is strong in this analysis, the overall findings about vitamin E have been complex. Further research on vitamin E in nonsmoking elderly males is warranted.
  • Hemila, Harri (2016)
    Analyses in nutritional epidemiology usually assume a uniform effect of a nutrient. Previously, four subgroups of the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study of Finnish male smokers aged 50-69 years were identified in which vitamin E supplementation either significantly increased or decreased the risk of pneumonia. The purpose of this present study was to quantify the level of true heterogeneity in the effect of vitamin E on pneumonia incidence using the I-2 statistic. The I-2 value estimates the percentage of total variation across studies that is explained by true differences in the treatment effect rather than by chance, with a range from 0 to 100 %. The I-2 statistic for the effect of vitamin E supplementation on pneumonia risk for five subgroups of the ATBC population was 89% (95% CI 78, 95 %), indicating that essentially all heterogeneity was true variation in vitamin E effect instead of chance variation. The I-2 statistic for heterogeneity in vitamin E effects on pneumonia risk was 92% (95% CI 80, 97 %) for three other ATBC subgroups defined by smoking level and leisure-time exercise level. Vitamin E decreased pneumonia risk by 69% among participants who had the least exposure to smoking and exercised during leisure time (7.6% of the ATBC participants), and vitamin E increased pneumonia risk by 68% among those who had the highest exposure to smoking and did not exercise (22% of the ATBC participants). These findings refute there being a uniform effect of vitamin E supplementation on the risk of pneumonia.
  • Hemilä, Harri (2009)
    Berry et al. studied the between-trial variation in the effect of vitamin E on mortality in 22 trials, concluding in the abstract that “vitamin E intake is unlikely to affect mortality regardless of dose.” However, their discussion of the vitamin E literature is biased to such an extent that it does not provide a proper context for their paper.