Harri Hemilä

Harri Hemilä
University of Helsinki | HY · Department of Public Health

MD, PhD

About

215
Publications
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Introduction
Harri Hemilä currently works at the Department of Public Health Science, University of Helsinki. Harri does research in Nutrition and Dietetics, Infectious Diseases and Immunology.

Publications

Publications (215)
Article
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Background Vitamin C deprivation can lead to fatigue, dyspnea, oedema and chest pain, which are also symptoms of heart failure (HF). In animal studies vitamin C has improved contractility and mechanical efficiency of the heart. Compared with healthy people, patients with HF have lower vitamin C levels, which are not explained by differences in diet...
Article
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Calculation of the difference of means is the most common approach when analyzing treatment effects on continuous outcomes. Nevertheless, it is possible that the treatment has a different effect on patients who have a lower value of the outcome compared with patients who have a greater value of the outcome. The estimation of quantile treatment effe...
Article
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Evidence has shown unambiguously that, in certain contexts, vitamin C is effective against the common cold. However, in mainstream medicine, the views on vitamin C and infections have been determined by eminence-based medicine rather than evidence-based medicine. The rejection of the demonstrated benefits of vitamin C is largely explained by three...
Technical Report
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In 2019, Philippe Vorilhon et al. published a meta-analysis on vitamin C for the prevention and treatment of upper respiratory tract infections in children (https://pubmed.ncbi.nlm.nih.gov/30465062). In a letter to the editor we pointed out several errors in the meta-analysis. Vorilhon et al. responded to our criticism, but we did not feel their re...
Article
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In this individual patient data meta‐analysis we examined datasets of two randomized placebo‐controlled trials which investigated the effect of nasal carrageenan separately on children and adults. In both trials, iota‐carrageenan was administered nasally three times per day for 7 days for patients with the common cold and follow‐up lasted for 21 da...
Preprint
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The COVID A to Z trial (JAMA Netw Open. 2021;4:e210369) is important as it focused specifically on SARS-CoV-2 coronavirus patients and examined a high dose of vitamin C which was previously predicted to reduce the duration of respiratory virus infections by about 20%. Unfortunately, there are several limitations in the trial methods. The COVID A to...
Article
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In numerous animal studies, vitamin C has prevented and alleviated viral and bacterial infections. In a few dozen placebo-controlled trials with humans, vitamin C has shortened infections caused by respiratory viruses, which indicates that the vitamin can also influence viral infections in humans. In critically ill patients, plasma vitamin C levels...
Article
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This Comment raises concerns about the article “Therapeutic target and molecular mechanism of vitamin C-treated pneumonia: a systematic study of network pharmacology”.
Preprint
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Carrageenan is a sulfated polysaccharide that has been extensively used in food products. Since the 1980s, carrageenan has been shown to prevent infections due to several viruses in cell cultures, including rhinoviruses which cause the common cold. In animal studies it prevented mortality caused by influenza A. Carrageenan is generally regarded as...
Article
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The Dietary Reference Intakes (DRI)-monograph (USA/Canada) states that the estimated average requirement (EAR) of vitamin E for men and women of any age is 12 mg/day. The EAR value is based on in vitro hemolysis in young males; a surrogate endpoint without any direct validity. The EAR is then extrapolated to females and older males. The validity of...
Article
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A previous analysis of the Alpha-Tocopherol Beta-Carotene (ATBC) Study on male smokers found that β-carotene supplementation increased the risk of pneumonia 4-fold in those who started smoking at the age of ≥21 years and smoked ≥21 cigarettes/d (a subgroup of 7 % of the study population). The present study hypothesised that β-carotene increases mor...
Article
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Background: Our recent meta-analysis indicated that vitamin C may shorten the length of ICU stay and the duration of mechanical ventilation. Here we analyze modification of the vitamin C effect on ventilation time, by the control group ventilation time (which we used as a proxy for severity of disease in the patients of each trial). Methods: We...
Article
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Objective To examine a commercially available zinc acetate lozenge for treating the common cold. Design Randomised, double-blinded, placebo-controlled trial. Setting Working population in Finland. Participants We included men and women aged ≥18 years who usually had ≥1 cold per winter. Exclusions were pregnancy, lactation, chronic runny nose or...
Article
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Background: The relative scale adjusts for baseline variability and therefore may lead to findings that can be generalized more widely. It is routinely used for the analysis of binary outcomes but only rarely for continuous outcomes. Our objective was to compare relative vs absolute scale pooled outcomes using data from a recently published Cochra...
Article
To the Editor Repeated clinical trials on a single medical intervention are never exact replications because patients differ and there are usually some variations in the intervention and outcome measurements. Such variations can lead to inconsistent results between studies on the same intervention.
Article
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A number of controlled trials have previously found that in some contexts, vitamin C can have beneficial effects on blood pressure, infections, bronchoconstriction, atrial fibrillation, and acute kidney injury. However, the practical significance of these effects is not clear. The purpose of this meta-analysis was to evaluate whether vitamin C has...
Article
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Beta-carotene has been suggested to be a factor for improving the immune system, which implies that it might decrease the risk of infections. We therefore analyzed whether beta-carotene supplementation influenced pneumonia risk in 14,564 Finnish male smokers of the Alpha-Tocopherol Beta-Carotene (ATBC) Study. There were 231 pneumonia cases in the b...
Article
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This is a protocol for a Cochrane Review (Intervention). The objectives are as follows: To assess the effects of zinc to reduce the incidence, duration and severity of the common cold when used either as a daily supplement to prevent colds or as therapy at the onset of cold symptoms or during a cold. © 2017 The Cochrane Collaboration. Published by...
Article
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Background The relative scale has been used for decades in analysing binary data in epidemiology. In contrast, there has been a long tradition of carrying out meta-analyses of continuous outcomes on the absolute, original measurement, scale. The biological rationale for using the relative scale in the analysis of binary outcomes is that it adjusts...
Article
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Objective To compare the efficacy of zinc acetate lozenges with zinc gluconate lozenges in common cold treatment and to examine the dose-dependency of the effect. Design Meta-analysis. Setting Placebo-controlled zinc lozenge trials, in which the zinc dose was > 75 mg/day. The pooled effect of zinc lozenges on common cold duration was calculated b...
Article
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Background A previous meta-analysis of 3 zinc acetate lozenge trials estimated that colds were on average 40% shorter for the zinc groups. However, the duration of colds is a time outcome and survival analysis may be a more informative approach. The objective of this individual patient data (IPD) meta-analysis was to estimate the effect of zinc ace...
Article
Full-text available
In the early literature, vitamin C deficiency was associated with pneumonia. After its identification, a number of studies investigated the effects of vitamin C on diverse infections. A total of 148 animal studies indicated that vitamin C may alleviate or prevent infections caused by bacteria, viruses, and protozoa. The most extensively studied hum...
Article
Baker and Coleman[1][1] conducted a meta-analysis of 11 studies on ascorbic acid for the prevention of postoperative atrial fibrillation (POAF). They concluded that perioperative administration of ascorbic acid reduces the frequency of POAF. However, the results of 2 rather large randomized
Article
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Background Atrial fibrillation (AF), a common arrhythmia contributing substantially to cardiac morbidity, is associated with oxidative stress and, being an antioxidant, vitamin C might influence it. Methods We searched the Cochrane CENTRAL Register, MEDLINE, and Scopus databases for randomised trials on vitamin C that measured AF as an outcome in h...
Article
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 purpos...
Article
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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 exam...
Chapter
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This is the protocol for a review and there is no abstract. The objectives are as follows: To assess the efficacy of vitamin C for treating AF, and for the secondary prevention of AF.
Article
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Aim: The aim of this study was to determine whether the allergy status and other characteristics of common cold patients modify the effects of zinc acetate lozenges. Methods: We had available individual patient data for three randomized placebo-controlled trials in which zinc acetate lozenges were administered to common cold patients. We used bo...
Article
To the Editor The JAMA Clinical Evidence Synopsis on zinc for the common cold by Drs Das and Singh1 was a summary of their Cochrane review.2 I noticed inconsistencies in the synopsis and so attempted to replicate their data.In the Evidence Profile section of the synopsis, the authors stated that the number of randomized clinical trials included was...
Article
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Placebos are allegedly used widely in general practice. Surveys reporting high level usage, however, have combined two categories, 'pure' and 'impure' placebos. The wide use of placebos is explained by the high level usage of impure placebos. In contrast, the prevalence of the use of pure placebos has been low. Traditional pure placebos are clinica...
Article
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Background A previous meta-analysis found that high dose zinc acetate lozenges reduced the duration of common colds by 42%, whereas low zinc doses had no effect. Lozenges are dissolved in the pharyngeal region, thus there might be some difference in the effect of zinc lozenges on the duration of respiratory symptoms in the pharyngeal region compar...
Article
Full-text available
This is the protocol for a review and there is no abstract. The objectives are as follows: To assess the efficacy of vitamin C for treating AF, and for the secondary prevention of AF.
Article
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Physical activity increases oxidative stress and therefore the antioxidant effects of vitamin C administration might become evident in people undertaking vigorous exercise. Vitamin C is involved in the metabolism of histamine, prostaglandins, and cysteinyl leukotrienes, all of which appear to be mediators in the pathogenesis of exercise-induced bro...
Article
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Observational studies identified associations between vitamin D insufficiency (serum 25(OH)D<30ng·mL1) and risk of upper respiratory infection (URI). Swimmers are highly prone to URIs, which might hinder their performance. The aim of this study was to examine if vitamin D3supplementation reduces URI burden in vitamin D-insufficient swimmers. Fifty-...
Article
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There is an obvious need for a critical discussion of the concepts 'placebo' and 'placebo effect'. In a recent paper on the use of placebos in clinical medicine, Gold and Lichtenberg note the conceptual difficulties but use the terminology in a confused way throughout their paper. In our response, we demonstrate these problems with a few examples f...
Article
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In this article, we first take a critical look at the definitions of evidence-based medicine (EBM) and complementary and alternative medicine (CAM). We then explore the question of whether there can be evidence-based forms of CAM. With the help of three examples, we show that EBM and CAM are not opposites, but rather concepts pointing at different...
Article
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Authors' conclusions A single, non-randomised, poorly reported trial of vitamin C as a treatment for tetanus suggests a considerable reduction in mortality. However, concerns about trial quality mean that this result must be interpreted with caution and vitamin C cannot be recommended as a treatment for tetanus on the basis of this evidence. New tr...
Article
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Asthma exacerbations are often induced by the common cold, which, in turn, can be alleviated by vitamin C. To investigate whether vitamin C administration influences common cold-induced asthma. Systematic review and statistical analysis of the identified trials. Medline, Scopus and Cochrane Central were searched for studies that give information on...
Technical Report
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In their meta-analysis, Bjelakovic et al. calculated that vitamin E in doses above the RDA (>15 mg) may slightly increase mortality by 3% (95% CI: 0% to 5%)(1). This estimate was based on the pooling of the results of 44 studies. However, study-level analyses can lead to different conclusions than do corresponding individual-level analysis, a diffe...
Article
Full-text available
Authors' conclusions The prophylactic use of vitamin C to prevent pneumonia should be further investigated in populations who have high incidence of pneumonia, especially if dietary vitamin C intake is low. Similarly, the therapeutic effects of vitamin C should be studied, especially in patients with low plasma vitamin C levels. The current evidenc...
Article
Full-text available
To determine whether vitamin C administration influences exercise-induced bronchoconstriction (EIB). Systematic review and meta-analysis. MEDLINE and Scopus were searched for placebo-controlled trials on vitamin C and EIB. The primary measures of vitamin C effect used in this study were: (1) the arithmetic difference and (2) the relative effect in...
Article
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Authors' conclusions The failure of vitamin C supplementation to reduce the incidence of colds in the general population indicates that routine vitamin C supplementation is not justified, yet vitamin C may be useful for people exposed to brief periods of severe physical exercise. Regular supplementation trials have shown that vitamin C reduces the...
Article
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Response to: Peters JL, Moreno SG, Phillips B, Sutton AJ. Are we sure about the evidence for zinc in prophylaxis of the common cold? Expert Rev. Respir. Med. 6(1), 15-16 (2012).
Article
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ABSTRACT: We reported that the effect of vitamin C on asthma in Egyptian children was modified by age, exposure to dampness and the severity of asthma, Clinical & Translational Allergy 2011, 1:9. After our paper was published, we found out severe problems in the data set. There were 60 children in the study. The ages were by accident duplicated bet...
Article
Selective serotonin reuptake inhibitors (SSRI) are commonly used to treat depression in pregnant women. Several adverse effects of prenatal SSRI exposure on the offspring have been described, including decreased growth. SSRI use by adults decreases bone mineral density, but this effect had not been examined in infants. To examine growth parameters...
Article
Full-text available
We previously found a significant benefit of vitamin C supplementation in asthmatic children. To test whether the effect of vitamin C on asthma is heterogeneous over the participant population. Egyptian asthmatic children between 7 and 10 years of age (n = 60) were included in the cross-over trial. They were administered 0.2 grams per day of vitami...
Data
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Additional file contains the protocol that was written before the subgroup analysis was initiated.
Article
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The risk of upper respiratory infections (URIs) is increased in people who are under heavy physical stress, including recreational and competitive swimmers. Additional treatment options are needed, especially in the younger age group. The aim of this study was to determine whether 1 g/day vitamin C supplementation affects the rate, length, or sever...
Data
This article contains supplementary material and it can be viewed at publisher’s website.
Article
Full-text available
A number of controlled trials have examined the effect of zinc lozenges on the common cold but the findings have diverged. The purpose of this study was to examine whether the total daily dose of zinc might explain part of the variation in the results. The Medline, Scopus and Cochrane Central Register of Controlled Trials data bases were searched f...
Article
Full-text available
antioxidants might protect against oxidative stress, which has been suggested as a cause of aging. the Alpha-Tocopherol-Beta-Carotene (ATBC) Study recruited males aged 50-69 years who smoked at least five cigarettes per day at the baseline. The current study was restricted to participants who were followed up past the age of 65. Deaths were identif...