-
1.
Intake and adequacy of the vegan diet. A systematic review of the evidence.
Bakaloudi, DR, Halloran, A, Rippin, HL, Oikonomidou, AC, Dardavesis, TI, Williams, J, Wickramasinghe, K, Breda, J, Chourdakis, M
Clinical nutrition (Edinburgh, Scotland). 2021;40(5):3503-3521
-
-
-
-
Free full text
Plain language summary
This systematic review investigated vegan diets in the European populations and their adequacy of macro-and micronutrient intake, compared to the recommendations of the World Health Organization. Included were 48 studies and their outcomes regarding protein, carbohydrates, fats and micronutrients summarized. The overall results and their impact on health are discussed in the later sections of the paper. Adequate intake amongst vegans was seen with carbohydrates, fats, Vitamin A, B1, В6, C, E, iron, phosphorus, magnesium, copper and folate. Sodium exceeded recommended intake, whilst protein, Vitamin B2, B3, B12, D, iodine, zinc, calcium, potassium, selenium was of low consumption in a vegan diet. The bioavailability of some nutrients was also acknowledged. In summary, following a vegan diet appears to have positive and negative aspects. A vegan diet profile can contribute to disease prevention with lower incidence rates of obesity, Type 2 diabetes, and cardiovascular disease. Yet veganism appears to increase the risk for mental health conditions, bone fractures, immune system impairments, anaemias and deficiencies from low nutrient intake. This review yields a comprehensive overview of the positive and negative health consequences of a vegan diet. It may be a useful reference for those looking to support vegans or individuals considering adopting a vegan diet pattern.
Expert Review
Conflicts of interest:
None
Take Home Message:
- Vegan diets in European populations tend to be lower in protein intake, particularly amino acids lysine, methionine and tryptophan.
- Other micronutrients that tend to lower in vegan diets are Vitamin B12, zinc, calcium and selenium.
- Healthcare practitioners should be aware of these potential deficiencies when working with vegan clients.
Evidence Category:
-
A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
-
X
B: Systematic reviews including RCTs of limited number
-
C: Non-randomized trials, observational studies, narrative reviews
-
D: Case-reports, evidence-based clinical findings
-
E: Opinion piece, other
Summary Review:
Vegan diets have become increasingly popular in the last ten years. This systematic review of 48 studies investigated the adequacy of vegan diets in European populations. It compared their macro- and micronutrient intakes compared to World Health Organization recommendations. It found that vegan diets tend to be lower in protein and in essential amino acids (lysine, methionine and tryptophan). They can also be lower in micronutrients especially vitamin B12, zinc, calcium and selenium. However, the lower intakes are not always associated with health impairments.
Clinical practice applications:
Practitioners should be aware of the potential deficiencies in a vegan diet.
Considerations for future research:
More research is needed to determine whether lower nutrient intakes in vegans correlated with poor health outcomes.
Abstract
BACKGROUND Vegan diets, where animal- and all their by-products are excluded from the diet, have gained popularity, especially in the last decade. However, the evaluation of this type of diet has not been well addressed in the scientific literature. This study aimed to investigate the adequacy of vegan diets in European populations and of their macro- and micronutrient intakes compared to World Health Organization recommendations. METHODS A systematic search in PubMed, Web of Science, IBSS, Cochrane library and Google Scholar was conducted and 48 studies (12 cohorts and 36 cross-sectional) were included. RESULTS Regarding macronutrients, vegan diets are lower in protein intake compared with all other diet types. Veganism is also associated with low intake of vitamins B2, Niacin (B3), B12, D, iodine, zinc, calcium, potassium, selenium. Vitamin B12 intake among vegans is significantly lower (0.24-0.49 μg, recommendations are 2.4 μg) and calcium intake in the majority of vegans was below recommendations (750 mg/d). No significant differences in fat intake were observed. Vegan diets are not related to deficiencies in vitamins A, B1, Β6, C, E, iron, phosphorus, magnesium, copper and folate and have a low glycemic load. CONCLUSIONS Following a vegan diet may result in deficiencies in micronutrients (vitamin B12, zinc, calcium and selenium) which should not be disregarded. However, low micro- and macronutrient intakes are not always associated with health impairments. Individuals who consume a vegan diet should be aware of the risk of potential dietary deficiencies.
-
2.
Manipulation of Dietary Intake on Changes in Circulating Testosterone Concentrations.
Zamir, A, Ben-Zeev, T, Hoffman, JR
Nutrients. 2021;13(10)
-
-
-
Free full text
Plain language summary
Androgens, like testosterone, are steroid hormones commonly associated with reproduction. However, they also govern metabolic functions, body composition and growth. Higher levels of circulating androgens enhance athletic performance by supporting metabolic activities such as protein production, regeneration and growth and by inhibiting breakdown processes. Manipulating testosterone to enhance athletic performance without the use of anabolic steroids hormones has been of much interest. As macro-and micronutrients can influence androgen hormones, this review examined whether specific energy and nutrient intake can ‘naturally’ manipulate testosterone levels. The authors describe the metabolic functions of testosterone before exploring the current evidence on selected plant extracts and nutrients and their impact on aromatase activity. Inhibiting aromatase can prevent androgens from being converted into oestrogen and thus may help to raise circulating androgens. Discussed are a range of plant-derived compounds, flavonoids, macronutrients and micronutrients (Vitamin D, Zinc and Magnesium) and their impact on testosterone levels. The authors conclude that the nutrients discussed have some supportive evidence, yet overall findings are inconclusive due to limited studies. Regarding macronutrients more research is available, and the evidence supports that low energy intake negatively impacts testosterone levels and performance. Whereby supplementation of vitamins crucial to testosterone production seems to provide value in cases of deficiency further research is required. This article yields an overview of plant compounds, macro-and micronutrients and their potential impact on circulating testosterone levels. While low energy intake and nutrient deficiencies appears to be unfavourable, the absence of clear evidence on other compounds would warrant further case-specific investigations.
Abstract
Elevations in the circulating concentration of androgens are thought to have a positive effect on the anabolic processes leading to improved athletic performance. Anabolic-androgenic steroids have often been used by competitive athletes to augment this effect. Although there has been concerted effort on examining how manipulating training variables (e.g., intensity and volume of training) can influence the androgen response to exercise, there has been much less effort directed at understanding how changes in both macronutrient and micronutrient intake can impact the androgen response. Thus, the focus of this review is to examine the effect that manipulating energy and nutrient intake has on circulating concentrations of testosterone and what the potential mechanism is governing these changes.
-
3.
Selenium, antioxidants, cardiovascular disease, and all-cause mortality: a systematic review and meta-analysis of randomized controlled trials.
Jenkins, DJA, Kitts, D, Giovannucci, EL, Sahye-Pudaruth, S, Paquette, M, Blanco Mejia, S, Patel, D, Kavanagh, M, Tsirakis, T, Kendall, CWC, et al
The American journal of clinical nutrition. 2020;112(6):1642-1652
-
-
-
Free full text
-
Plain language summary
Oxidative damage is a shared characteristic in chronic diseases such as cardiovascular disease (CVD), diabetes, cancer and ageing. Antioxidants mitigate the impact of oxidants and have been widely investigated in ageing and disease. However, the evidence for supplementary antioxidants has been mixed and some authorities have advised against the use of certain single nutrients for the prevention of CVD or cancer. This systematic review and meta-analysis focused on selenium due to its vital role in the antioxidant system and associations of low selenium blood levels with increased risk of CVD, cancers and death. The study included 43 randomised controlled trials (RCTs) evaluating the effect of supplemental selenium and antioxidants with or without selenium and their impact on CVD risk, cancer and all-cause mortality. Overall supplemental selenium or antioxidants alone did not seem to be associated with CVD outcomes, cancer, CVD and cancer mortality, or all-cause mortality. On close examination, a decreased risk was seen for CVD mortality when antioxidants were combined with selenium, whilst antioxidant mixtures without selenium demonstrated an increased risk in all-cause mortality. The findings did not seem to be influenced by dietary selenium intake. The authors suggested that inclusion of selenium as part of an antioxidant mix could be key for an antioxidant associated risk reduction. However, in the absence of further long term studies, a balanced antioxidant-rich diet was advocated as the safest approach. In clinical practice, where antioxidant support beyond diet is warranted, supplemental antioxidant use should be concurrent with adequate selenium supplementation, with dose benefits of 50-200mcg observed.
Abstract
BACKGROUND Antioxidants have been promoted for cardiovascular disease (CVD) risk reduction and for the prevention of cancer. Our preliminary analysis suggested that only when selenium was present were antioxidant mixtures associated with reduced all-cause mortality. OBJECTIVE We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to determine the effect of selenium supplementation alone and of antioxidant mixtures with or without selenium on the risk of CVD, cancer, and mortality. METHODS We identified studies using the Cochrane Library, Medline, and Embase for potential CVD outcomes, cancer, and all-cause mortality following selenium supplementation alone or after antioxidant supplement mixtures with and without selenium up to June 5, 2020. RCTs of ≥24 wk were included and data were analyzed using random-effects models and classified by the Grading of Recommendations, Assessment, Development, and Evaluation approach. RESULTS The meta-analysis identified 9423 studies, of which 43 were used in the final analysis. Overall, no association of selenium alone or antioxidants was seen with CVD and all-cause mortality. However, a decreased risk with antioxidant mixtures was seen for CVD mortality when selenium was part of the mix (RR: 0.77; 95% CI: 0.62, 0.97; P = 0.02), with no association when selenium was absent. Similarly, when selenium was part of the antioxidant mixture, a decreased risk was seen for all-cause mortality (RR: 0.90; 95% CI: 0.82, 0.98; P = 0.02) as opposed to an increased risk when selenium was absent (RR: 1.09; 95% CI: 1.04, 1.13; P = 0.0002). CONCLUSION The addition of selenium should be considered for supplements containing antioxidant mixtures if they are to be associated with CVD and all-cause mortality risk reduction. This trial was registered at https://www.crd.york.ac.uk/PROSPERO/ as CRD42019138268.
-
4.
Thyroid-Gut-Axis: How Does the Microbiota Influence Thyroid Function?
Knezevic, J, Starchl, C, Tmava Berisha, A, Amrein, K
Nutrients. 2020;12(6)
-
-
-
Free full text
Plain language summary
Thyroid and gut disease often coexist together. This literature review highlights the strong interplay between gut, microbiota and thyroid disease. In autoimmune thyroid disease (AITD) gut bacteria imbalances, bacterial overgrowth, Coeliac's disease or non-coeliacs wheat sensitivity, increased gut permeability and resulting deficiency of thyroid nutrients are not uncommon. Inflammation and intestinal wall damage that lead to increased permeability are thought to be one of the driving factors for autoimmune activity. Allergens, certain drugs, impaired gut flora and nutrient deficiencies are some of the contributors to heightened intestinal permeability. Furthermore, the gut walls host deiodinase enzymes that convert thyroid hormone to its active form. The gut microbiota however influence thyroid function in their own rights. The bacteria are crucial for nutrient synthesis, absorption and availability, including those essential for thyroid health. Gut bacteria and their metabolites also play a significant role in the regulation, development and training of immune cells, relevant to AITD. After all, the gut also houses a large proportion of the immune system known as gut-associated lymphatic tissue (GALT). Besides, some bacteria species seem to be capable of balancing fluctuating thyroid hormone levels in the blood. The writings further elaborate on thyroid-essential nutrients and the gut such as iodine, iron, zinc, selenium and Vitamin D. And the impact of bariatric surgery on thyroid function and the presence of certain gut bacteria in thyroid cancers. In summary, the authors concluded that the thyroid-gut axis seems to exhibit a strong connection. Limited evidence from human studies showed promising results of probiotics and synbiotics on thyroid function and targeting the microbiota as a novel strategies for the management of thyroid disease is encouraged to be explored further. This article may be of interest to those looking for an informative summary on the many ways in which the gut influences thyroid function in health and disease.
Abstract
A healthy gut microbiota not only has beneficial effects on the activity of the immune system, but also on thyroid function. Thyroid and intestinal diseases prevalently coexist-Hashimoto's thyroiditis (HT) and Graves' disease (GD) are the most common autoimmune thyroid diseases (AITD) and often co-occur with Celiac Disease (CD) and Non-celiac wheat sensitivity (NCWS). This can be explained by the damaged intestinal barrier and the following increase of intestinal permeability, allowing antigens to pass more easily and activate the immune system or cross-react with extraintestinal tissues, respectively. Dysbiosis has not only been found in AITDs, but has also been reported in thyroid carcinoma, in which an increased number of carcinogenic and inflammatory bacterial strains were observed. Additionally, the composition of the gut microbiota has an influence on the availability of essential micronutrients for the thyroid gland. Iodine, iron, and copper are crucial for thyroid hormone synthesis, selenium and zinc are needed for converting T4 to T3, and vitamin D assists in regulating the immune response. Those micronutrients are often found to be deficient in AITDs, resulting in malfunctioning of the thyroid. Bariatric surgery can lead to an inadequate absorption of these nutrients and further implicates changes in thyroid stimulating hormone (TSH) and T3 levels. Supplementation of probiotics showed beneficial effects on thyroid hormones and thyroid function in general. A literature research was performed to examine the interplay between gut microbiota and thyroid disorders that should be considered when treating patients suffering from thyroid diseases. Multifactorial therapeutic and preventive management strategies could be established and more specifically adjusted to patients, depending on their gut bacteria composition. Future well-powered human studies are warranted to evaluate the impact of alterations in gut microbiota on thyroid function and diseases.
-
5.
The impact of nutrition and lifestyle on male fertility.
Benatta, M, Kettache, R, Buchholz, N, Trinchieri, A
Archivio italiano di urologia, andrologia : organo ufficiale [di] Societa italiana di ecografia urologica e nefrologica. 2020;92(2)
-
-
-
Free full text
Plain language summary
The impact of environmental, lifestyle and nutritional factors on unexplained male fertility has long been acknowledged. Yet, little research had been dedicated to the topic, despite declining semen quality having become a worldwide phenomena. Available studies have yielded limited, and at times conflicting, evidence. Hence this literature review sought to capture the current knowledge around unexplained male infertility and environmental, lifestyle, diet and nutrients factors. Summarized is the evidence from 69 studies, including population observations and clinical trials. The collected outcomes showed that a Western-type diet, rich in red and processed meats, refined grains, high-energy drinks and sweets, trans and saturated fats was associated with poor semen quality. Whereby higher intakes of fruits and vegetables, whole grains, omega-3 and poultry showed beneficial effects. However, as only selected groups were examined, more research is needed to project such findings onto the wider population. The reviewed evidence also included alcohol consumption, which showed high alcohol intake closely correlated to declining sperm concentrations. Whilst the verdict on caffeine consumption and the impact on sperm quality was inconclusive. In addition, several interventional studies evaluated the effect of dietary supplementation on various parameters of semen, where coenzyme Q10, L-carnitine, vitamin E, antioxidants, combined nutrient formulations and herbal blends all had positive outcomes. The review on zinc and folic acid supplementation yielded mixed results. This brief recap of the current evidence on environmental, lifestyle and nutritional influences on male infertility summarises the dietary foundations for the support of unexplained male infertility.
Abstract
BACKGROUND AND AIMS Male unexplained infertility has long been suspected to result from environmental, lifestyle and nutritional factors. However, the literature on the subject is still scarce, and clinical studies providing robust evidence are even scarcer. In addition, some similar studies come to different conclusions. Dietary pattern can influence spermatogenesis by its content of fatty acids and antioxidants. Yet, in an age of industrialized mass food production, human bodies become more exposed to the ingestion of xenobiotics, as well as chemicals used for production, preservation, transportation and taste enhancement of foods. We attempted in this paper to collect the available evidence to date on the effect of nutritional components on male fertility. MATERIAL AND METHODS A systematic search of the relevant literature published in PubMed, ScienceDirect and Cochrane Central Register of Controlled Trials Database was conducted. Literature was evaluated according to the Newcastle-Ottawa- Scale. RESULTS Epidemiological observations are concordant in demonstrating an association of low-quality sperm parameters with higher intake of red meat, processed and organ meat and fullfat dairy. On the contrary, better semen parameters were observed in subjects consuming a healthy diet, rich in fruit, vegetables, whole grains and fish. Evidences of the negative impact on male fertility of by-products of water disinfection, accumulation in food chain of persistent organochlorine pollutants, pesticides, phthalates from food and water containers and hormones used in breeding cattle have been reported. Clinical trials of the effects of micronutrients on semen parameters and outcomes of assisted fertilization are encouraging, although optimal modality of treatment should be established. CONCLUSIONS Although quality of evidence should be ameliorated, it emerges that environmental factors can influence male fertility. Some nutrients may enhance fertility whereas others will worsen it. With diagnostic analysis on a molecular or even sub-molecular level, new interactions with micronutrients or molecular components of our daily ingested foods and leisure drugs may lead to a better understanding of so far suspected but as yet unexplained effects on male spermatogenesis and fertility.
-
6.
Inflammaging and Oxidative Stress in Human Diseases: From Molecular Mechanisms to Novel Treatments.
Zuo, L, Prather, ER, Stetskiv, M, Garrison, DE, Meade, JR, Peace, TI, Zhou, T
International journal of molecular sciences. 2019;20(18)
-
-
-
Free full text
Plain language summary
Reactive oxygen species (ROS) are produced during normal metabolic processes or can be induced by environmental factors. High levels of ROS in the cell can lead to oxidation causing cellular damage and a subsequent increase in inflammation, which is a significant contributor to disease. Age-associated increases in such chronic, low-grade inflammation is also referred to as inflammaging. This review summarizes how inflammaging plays a role in various age-related health conditions. Described are the mechanisms of how ROS and the age-related decline in cellular turn-over and immune activation contribute to the pathology of cardiovascular disease, cancer, neurodegeneration concerning Alzheimer’s and Parkinson’s disease, diabetes and rheumatoid arthritis. Furthermore, the authors discuss potential treatments that could assist in the management of such inflammaging-related diseases. These include vaccines to stimulate immune activity, stem cell intervention, drugs like metformin, nutritional and nutraceutical supplements like zinc, vitamin E, vitamins C, D, carotenoids, polyphenols and flavonoids like resveratrol, red algae extract and melatonin. Addressed are also general dietary concepts like calorie restriction, the benefits of the Mediterranean diet or a whole foods diet, and the potential of specific plant derived compounds like baicalin and sulforaphanes. The authors also briefly highlight the importance of the gut microbiome, as a poor gut microbiota has been associated with unfavourable age-related immune alterations and overall inflammaging. This review provides a comprehensive resource, detailing the effects and mechanisms of oxidative damage and its contribution to age-related diseases, including a list of interventions to consider when navigating the impact and risks associated with inflammaging.
Abstract
It has been proposed that a chronic state of inflammation correlated with aging known as inflammaging, is implicated in multiple disease states commonly observed in the elderly population. Inflammaging is associated with over-abundance of reactive oxygen species in the cell, which can lead to oxidation and damage of cellular components, increased inflammation, and activation of cell death pathways. This review focuses on inflammaging and its contribution to various age-related diseases such as cardiovascular disease, cancer, neurodegenerative diseases, chronic obstructive pulmonary disease, diabetes, and rheumatoid arthritis. Recently published mechanistic details of the roles of reactive oxygen species in inflammaging and various diseases will also be discussed. Advancements in potential treatments to ameliorate inflammaging, oxidative stress, and consequently, reduce the morbidity of multiple disease states will be explored.
-
7.
Vegan Nutrition for Mothers and Children: Practical Tools for Healthcare Providers.
Baroni, L, Goggi, S, Battaglino, R, Berveglieri, M, Fasan, I, Filippin, D, Griffith, P, Rizzo, G, Tomasini, C, Tosatti, MA, et al
Nutrients. 2018;11(1)
-
-
-
Free full text
Plain language summary
Vegan diets have grown in popularity and so healthcare practitioners need to be adequately educated to be able to give advice, as if they are properly planned, they can give adequate nutrition throughout all stages of life. This review study aimed to summarise the findings of the Scientific Society for Vegetarian Nutrition (SSNV) on vegan diets throughout pregnancy, breastfeeding, infancy, and childhood to provide recommendations for healthcare professionals. The paper starts by defining a well-planned vegan diet as high in a variety of whole or minimally processed plant foods, which meets the required amount of energy. In addition, minimising vegetable fats and avoiding trans fats to not displace other nutrient-dense foods is a requirement of a vegan diet with sufficient nutrition. Adequate amounts of calcium are also needed to be a complete vegan diet and vitamin B12, and vitamin D should be obtained from alternative sources, which are lacking in plant-based diets. The paper then goes on to recommend sources and requirements of protein, fibre, omega-3 fatty acids, iron, zinc, iodine, calcium, vitamin D, and vitamin B12 in vegans during pregnancy, lactation, infancy, and childhood. Many positives of a vegan diet were outlined such as increased fibre benefitting gut bacteria and high iron intakes. It was concluded that adequately planned vegan diets can provide sufficient nutrition at all stages of pregnancy and early life and instances of malnutrition in vegans is usually due to an inappropriate diet. Healthcare professionals could use this paper to understand what defines a complete vegan diet and sources of critical nutrients to ensure that vegan clients and patients are receiving adequate nutrient amounts.
Abstract
As the number of subjects choosing vegan diets increases, healthcare providers must be prepared to give the best advice to vegan patients during all stages of life. A completely plant-based diet is suitable during pregnancy, lactation, infancy, and childhood, provided that it is well-planned. Balanced vegan diets meet energy requirements on a wide variety of plant foods and pay attention to some nutrients that may be critical, such as protein, fiber, omega-3 fatty acids, iron, zinc, iodine, calcium, vitamin D, and vitamin B12. This paper contains recommendations made by a panel of experts from the Scientific Society for Vegetarian Nutrition (SSNV) after examining the available literature concerning vegan diets during pregnancy, breastfeeding, infancy, and childhood. All healthcare professionals should follow an approach based on the available evidence in regard to the issue of vegan diets, as failing to do so may compromise the nutritional status of vegan patients in these delicate periods of life.
-
8.
Vegan diets: practical advice for athletes and exercisers.
Rogerson, D
Journal of the International Society of Sports Nutrition. 2017;14:36
-
-
-
Free full text
Plain language summary
Veganism has increased in popularity in recent years and amongst those converting to a plant-based diet are several high profile athletes. Yet, in sports nutrition little is known about vegan diets and their impact on exercise and athletic performance. A common concern with strict restrictive eating patterns is that a poorly designed diet can predispose to macro-and micronutrient insufficiency. By drawing from other areas of research, this review sought to summarise available evidence to formulate nutritional recommendations that can meet the health and performance needs of those following a vegan diet. Discussed are the macro-and micronutrients most critical in a vegan diet, including total energy intake. Detailed paragraphs address protein adequacy, amino acid profiles, branch chained amino acids and their importance for muscle synthesis and digestibility. Elaborated are issues around carbohydrates and fibre, as well as fat intake and omega-3 fatty acids. The review also covers micronutrients that tend to have insufficient intake in a vegan diet and their role in sports performance. Including Vitamin B12, iron, zinc, iodine, calcium and vitamin D, with a final note on the performance-enhancing amino acids of creatine and beta-alanine. The authors also suggest food sources for the relevant nutrients and included sample meal plans. This review provides a comprehensive and practical guide for those providing nutritional support to vegan sportspeople and athletes.
Abstract
With the growth of social media as a platform to share information, veganism is becoming more visible, and could be becoming more accepted in sports and in the health and fitness industry. However, to date, there appears to be a lack of literature that discusses how to manage vegan diets for athletic purposes. This article attempted to review literature in order to provide recommendations for how to construct a vegan diet for athletes and exercisers. While little data could be found in the sports nutrition literature specifically, it was revealed elsewhere that veganism creates challenges that need to be accounted for when designing a nutritious diet. This included the sufficiency of energy and protein; the adequacy of vitamin B12, iron, zinc, calcium, iodine and vitamin D; and the lack of the long-chain n-3 fatty acids EPA and DHA in most plant-based sources. However, via the strategic management of food and appropriate supplementation, it is the contention of this article that a nutritive vegan diet can be designed to achieve the dietary needs of most athletes satisfactorily. Further, it was suggested here that creatine and β-alanine supplementation might be of particular use to vegan athletes, owing to vegetarian diets promoting lower muscle creatine and lower muscle carnosine levels in consumers. Empirical research is needed to examine the effects of vegan diets in athletic populations however, especially if this movement grows in popularity, to ensure that the health and performance of athletic vegans is optimised in accordance with developments in sports nutrition knowledge.
-
9.
Zinc lozenges and the common cold: a meta-analysis comparing zinc acetate and zinc gluconate, and the role of zinc dosage.
Hemilä, H
JRSM open. 2017;8(5):2054270417694291
-
-
-
Free full text
Plain language summary
Zinc lozenges are sometimes used to reduce the symptoms of the common cold. However studies have had varying results, possibly due to using different doses, as well as different forms of zinc. The aim of this meta-analysis was to compare the efficacy of zinc acetate lozenges with zinc gluconate lozenges in reducing the duration of the common cold and to examine the dose-dependency of the effect. The study authors looked at seven randomised trials with 575 participants with common colds. All of the trials were placebo-controlled and used zinc doses of over 75 mg/day. Three of the trials used zinc lozenges composed of zinc acetate, and four used zinc gluconate. Overall, zinc lozenges reduced cold duration by 33% compared to a placebo. The trials that used lozenges composed of zinc acetate found that colds were shortened by 40% and zinc gluconate reduced duration by 28%. The difference between the two forms was not statistically significant. Five trials used zinc doses of 80–92 mg/day, and common cold duration was reduced by 33%. Two trials used zinc doses of 192–207 mg/day and found an effect of 35%. The difference was not statistically significant. The authors concluded that zinc gluconate lozenges are equally as effective as zinc acetate lozenges. There is no evidence that zinc doses over 100 mg/day are more effective in reducing the duration of the common cold.
Abstract
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 by using inverse-variance random-effects method. PARTICIPANTS Seven randomised trials with 575 participants with naturally acquired common colds. MAIN OUTCOME MEASURE Duration of the common cold. RESULTS The mean common cold duration was 33% (95% CI 21% to 45%) shorter for the zinc groups of the seven included trials. Three trials that used lozenges composed of zinc acetate found that colds were shortened by 40% and four trials that used zinc gluconate by 28%. The difference between the two salts was not significant: 12 percentage points (95% CI: -12 to + 36). Five trials used zinc doses of 80-92 mg/day, common cold duration was reduced by 33%, and two trials used zinc doses of 192-207 mg/day and found an effect of 35%. The difference between the high-dose and low-dose zinc trials was not significant: 2 percentage points (95% CI: -29 to + 32). CONCLUSIONS Properly composed zinc gluconate lozenges may be as effective as zinc acetate lozenges. There is no evidence that zinc doses over 100 mg/day might lead to greater efficacy in the treatment of the common cold. Common cold patients may be encouraged to try zinc lozenges for treating their colds. The optimal lozenge composition and dosage scheme need to be investigated further.