We explored how vitamin C affects the severity of common colds through a comprehensive review of available studies. By including only randomized, placebo-controlled trials where participants received at least 1 gram of vitamin C daily, we aimed to investigate both the overall duration of colds and the intensity of symptoms experienced.
Our analysis found that vitamin C significantly reduced the severity of cold symptoms by about 15%. Interestingly, it appears that the benefits are more pronounced for those experiencing severe symptoms compared to mild ones. In specific comparisons, vitamin C didn’t substantially affect the duration of mild symptoms but had a notable impact on how long severe symptoms lasted.
This insight is crucial, as the common cold often leads to absenteeism at work and school, with more severe symptoms playing a key role in this setback. By highlighting vitamin C's greater effectiveness against intense cold symptoms, we suggest that future research should continue to look into how this vitamin can be utilized in managing cold severity.
Read More
8
Vitamin C's potential benefits highlighted
Bias against Vitamin C in Mainstream Medicine: Examples from Trials of Vitamin C for Infections.
We assessed the longstanding debate about vitamin C’s effectiveness in treating the common cold. This exploration reveals that evidence has consistently indicated that vitamin C can indeed help reduce the duration and severity of cold symptoms in certain circumstances.
However, despite this evidence, mainstream medicine has often favored what we call eminence-based medicine, relying on influential figures rather than empirical data. The skepticism surrounding vitamin C largely traces back to three pivotal studies published in 1975, two in JAMA and one in the American Journal of Medicine. These studies have shaped the narrative in textbooks and nutritional guidelines, despite exhibiting notable flaws that we carefully examined.
Furthermore, we highlighted misleading reporting in recent randomized trials and critical editorials published in JAMA regarding vitamin C. While our critique largely focuses on this journal, it reflects a broader trend across medical literature, indicating a possible bias against acknowledging the benefits of vitamin C in fighting colds.
Read More
8
Vitamin C reduces cold incidence
Vitamin C supplementation reduces the odds of developing a common cold in Republic of Korea Army recruits: randomised controlled trial.
We conducted an insightful study to explore whether vitamin C supplementation can help reduce the incidence of common colds among Republic of Korea Army recruits. Our research involved a rigorous randomised, placebo-controlled trial that included 1,444 soldiers over a 30-day period.
In this study, we divided the participants into two groups: one received a daily dose of 6,000 mg of vitamin C while the other received a placebo with no vitamin C. We investigated the soldiers' medical records to see how many of them contracted a cold during the training period.
Our findings showed encouraging results. The group that took vitamin C had a 20% lower risk of developing a common cold compared to those who took the placebo. Interestingly, this protective effect was especially pronounced among recruits in certain training camps, as well as never smokers and those who were physically ranked at level three.
Overall, we observed that vitamin C supplementation appears to be an effective strategy for reducing the incidence of common colds in military settings, which may lead to considerations for implementing vitamin C provisions during basic training for soldiers.
Read More
Most Useful Reviews
9
Cold relief observed
2 people found this helpful
Excellent product! It's gentle on my stomach, and I've noticed relief from the symptoms of the common cold, as well as an overall improvement in my health.
Read More
7.5
Good even fasting
2 people found this helpful
Whole food-based supplements are good even on an empty stomach. They don’t upset my stomach. When feeling run down due to the common cold, I find they help with quicker recovery, especially when taken in larger amounts.
Read More
9
Prevention method
1 people found this helpful
I switched to Mega Foods' vitamin C, extracted from food, years ago. I believe this has helped me avoid catching colds and stay healthy. It's beneficial for my skin, too.
We explored the potential benefits of vitamin C as a supplementary treatment for relieving common cold symptoms. By analyzing data from 10 randomized controlled trials, all focused on patients in China, we sought to understand how combining vitamin C with antiviral therapy might enhance recovery.
Our findings revealed that vitamin C supplementation could significantly improve overall efficacy, with a reported relative risk of 1.27. Moreover, it was shown to shorten the time it takes for symptoms to get better and for patients to heal, compared to antiviral therapy alone.
While vitamin C seems to have a positive impact when paired with antiviral drugs, it’s essential to note that its individual effects might not be fully clear due to the combined treatment approach used in the studies. Nonetheless, vitamin C presents itself as a promising addition to traditional cold treatments, helping patients manage their symptoms more effectively.
Read More
8
Vitamin C reduces cold severity
Vitamin C reduces the severity of common colds: a meta-analysis.
We explored how vitamin C affects the severity of common colds through a comprehensive review of available studies. By including only randomized, placebo-controlled trials where participants received at least 1 gram of vitamin C daily, we aimed to investigate both the overall duration of colds and the intensity of symptoms experienced.
Our analysis found that vitamin C significantly reduced the severity of cold symptoms by about 15%. Interestingly, it appears that the benefits are more pronounced for those experiencing severe symptoms compared to mild ones. In specific comparisons, vitamin C didn’t substantially affect the duration of mild symptoms but had a notable impact on how long severe symptoms lasted.
This insight is crucial, as the common cold often leads to absenteeism at work and school, with more severe symptoms playing a key role in this setback. By highlighting vitamin C's greater effectiveness against intense cold symptoms, we suggest that future research should continue to look into how this vitamin can be utilized in managing cold severity.
Read More
8
Vitamin C's potential benefits highlighted
Bias against Vitamin C in Mainstream Medicine: Examples from Trials of Vitamin C for Infections.
We assessed the longstanding debate about vitamin C’s effectiveness in treating the common cold. This exploration reveals that evidence has consistently indicated that vitamin C can indeed help reduce the duration and severity of cold symptoms in certain circumstances.
However, despite this evidence, mainstream medicine has often favored what we call eminence-based medicine, relying on influential figures rather than empirical data. The skepticism surrounding vitamin C largely traces back to three pivotal studies published in 1975, two in JAMA and one in the American Journal of Medicine. These studies have shaped the narrative in textbooks and nutritional guidelines, despite exhibiting notable flaws that we carefully examined.
Furthermore, we highlighted misleading reporting in recent randomized trials and critical editorials published in JAMA regarding vitamin C. While our critique largely focuses on this journal, it reflects a broader trend across medical literature, indicating a possible bias against acknowledging the benefits of vitamin C in fighting colds.
Read More
8
Vitamin C reduces cold incidence
Vitamin C supplementation reduces the odds of developing a common cold in Republic of Korea Army recruits: randomised controlled trial.
We conducted an insightful study to explore whether vitamin C supplementation can help reduce the incidence of common colds among Republic of Korea Army recruits. Our research involved a rigorous randomised, placebo-controlled trial that included 1,444 soldiers over a 30-day period.
In this study, we divided the participants into two groups: one received a daily dose of 6,000 mg of vitamin C while the other received a placebo with no vitamin C. We investigated the soldiers' medical records to see how many of them contracted a cold during the training period.
Our findings showed encouraging results. The group that took vitamin C had a 20% lower risk of developing a common cold compared to those who took the placebo. Interestingly, this protective effect was especially pronounced among recruits in certain training camps, as well as never smokers and those who were physically ranked at level three.
Overall, we observed that vitamin C supplementation appears to be an effective strategy for reducing the incidence of common colds in military settings, which may lead to considerations for implementing vitamin C provisions during basic training for soldiers.
We investigated how vitamin C affects the common cold, focusing on its potential for prevention and treatment. Research indicates that while vitamin C does not prevent colds in the general population when taken at doses over 1 g/day, it has been beneficial for individuals engaging in heavy physical activity, effectively halving their incidence of colds.
Looking into regular supplementation, we found that taking 1 g or more daily can reduce the severity of colds by about 15%. However, when it comes to starting vitamin C after cold symptoms begin, results are less consistent, though higher doses of 6-8 g/day did significantly shorten the duration of colds compared to lower doses.
Interestingly, historical studies showed that vitamin C might prevent pneumonia in specific populations, such as schoolboys or soldiers, but this doesn’t translate to the general public. While some trials indicated potential benefits for pneumonia patients, the evidence is not conclusive.
Overall, we see that given the evidence supporting reduced severity and duration of colds, along with its safety and affordability, it may be worth considering a higher dose of vitamin C for those looking to manage cold symptoms better.
Excellent product! It's gentle on my stomach, and I've noticed relief from the symptoms of the common cold, as well as an overall improvement in my health.
Read More
7.5
Good even fasting
2 people found this helpful
Whole food-based supplements are good even on an empty stomach. They don’t upset my stomach. When feeling run down due to the common cold, I find they help with quicker recovery, especially when taken in larger amounts.
Read More
9
Prevention method
1 people found this helpful
I switched to Mega Foods' vitamin C, extracted from food, years ago. I believe this has helped me avoid catching colds and stay healthy. It's beneficial for my skin, too.
Read More
9
Essential for immunity
This vitamin C is excellent! It's essential during cold and flu season and for daily immune boosts. It doesn’t upset my sensitive stomach and tastes fine.
Read More
9
Immunity booster
It's fantastic and raises immunity against the common cold and flu effectively.
The common cold is a viral infection of the upper respiratory tract, primarily affecting the nose and throat. It's caused by a variety of viruses, with rhinoviruses being the most prevalent. Symptoms generally include a runny or stuffy nose, sore throat, cough, sneezing, mild headache, and sometimes a low-grade fever. While the common cold is often mild and resolves on its own within a week or two, it can still be bothersome and impact daily activities.
Transmission occurs through respiratory droplets when an infected person coughs or sneezes, or by touching surfaces contaminated with the virus. Preventative measures include frequent handwashing, using hand sanitizer, and avoiding close contact with infected individuals. Since there is currently no cure for the common cold, treatment focuses on symptom relief through over-the-counter medications, adequate rest, and hydration. While colds may be uncomfortable, they are generally not serious; however, seeking medical attention may be necessary if symptoms worsen or persist for an extended period.
Vitamin C, also known as ascorbic acid, is a water-soluble vitamin that plays a critical role in numerous bodily functions. As an essential nutrient, it contributes to the growth and repair of tissues in the body, and it is vital for the production of collagen, an important protein that helps maintain skin, cartilage, tendons, ligaments, and blood vessels. Additionally, Vitamin C acts as a powerful antioxidant, which means it helps combat free radicals—unstable molecules that can cause oxidative stress and contribute to various chronic diseases.
Moreover, Vitamin C enhances iron absorption from plant-based foods, making it a vital component for those following vegetarian or vegan diets. While many people get sufficient Vitamin C from a well-balanced diet that includes fruits and vegetables like oranges, strawberries, kiwi, broccoli, and bell peppers, some individuals might require supplementation. It's generally recommended to stay within the daily intake guidelines, as excessive consumption can lead to gastrointestinal disturbances. Overall, Vitamin C is not just a skincare celebrity—it's a fundamental part of maintaining overall health and well-being.
Vitamin C has long been touted as a remedy for the common cold, but the evidence supporting its efficacy is mixed. Some studies suggest that regular consumption of Vitamin C may reduce the duration and severity of cold symptoms, particularly in individuals who engage in intense physical activity or have a deficiency in this vitamin. However, for the average person, taking Vitamin C after the onset of cold symptoms is generally not shown to have a significant impact on shortening the cold.
If you're considering using Vitamin C to fend off colds, incorporating it into your daily routine through fruits and vegetables, such as oranges, strawberries, and bell peppers, can support overall immune function. Supplements might be beneficial for those who struggle to get enough from their diet, but they are not a guaranteed cure. While Vitamin C isn't a magic bullet against the common cold, maintaining adequate levels can contribute to overall health and may help mitigate some symptoms. However, always consult with a healthcare provider before starting any new supplement regimens.
Based on user reviews, the time it typically takes to see results from taking vitamin C supplements for the common cold varies among users, with many reporting improvements shortly after beginning their regimen. For instance, one user mentioned experiencing relief from symptoms and an overall boost in health soon after starting the product, suggesting a quick response time Read Review. Others have noted that taking a larger loading dose could lead to quicker recovery when feeling run down due to cold symptoms Read Review.
Several users have expressed confidence in the product's effectiveness during cold and flu season, indicating that a consistent daily intake may help prevent colds and strengthen the immune system over time Read Review, Read Review. However, individual experiences may vary, and some users may find that the benefits become noticeable only after regular use Read Review. Overall, incorporating vitamin C into your routine seems to yield results that can range from immediate relief to ongoing immune support.
Research data supports the idea that vitamin C can be beneficial in managing the common cold, particularly in terms of reducing the severity and duration of symptoms. Numerous studies have shown that daily supplementation of at least 1 gram can lead to a 15% reduction in cold symptom intensity. For individuals engaging in heavy physical activities, high doses of vitamin C (6-8 g/day) significantly shortened recovery time from colds, leading to better outcomes than lower doses or no supplementation at all [1], [2]. Furthermore, evidence suggests that vitamin C may be particularly advantageous for those under physical or environmental stress, such as soldiers, where supplementation led to a 20% reduction in the risk of colds [7].
Despite the highlighted benefits, it's important to note that vitamin C does not prevent all colds in the general population and its effectiveness appears to diminish when started after symptoms have already manifested [4]. Nonetheless, for those seeking relief from greater cold severity—especially during stressful situations—higher doses of vitamin C could be worth considering. As the exact efficacy of vitamin C remains an ongoing topic of research, it’s advisable to consult with a healthcare provider before starting any new supplementation [3], [6].
Based on user reviews, many individuals have reported noticeable improvements in their symptoms after incorporating vitamin C into their routines. For instance, one user mentioned experiencing relief from cold symptoms and an overall boost in health shortly after starting the product Read Review. Others have emphasized the effectiveness of higher doses for quicker recovery during cold episodes, suggesting that more concentrated intake might lead to faster relief from symptoms Read Review. Many users find that consistent use can help in preventing colds altogether, reporting fewer instances of catching colds and improved overall immune health over time Read ReviewRead Review.
Furthermore, those with sensitive stomachs have noted that this particular vitamin C formulation does not upset their digestion, allowing them to take it regularly without discomfort Read Review. Users have also remarked that even during intense cold and flu seasons, they felt confident using these supplements to support their immune systems Read Review. However, it's important to note that individual results can vary, with some, like one user, experiencing adverse effects such as heartburn from natural vitamin C Read Review. Overall, many users seem to find this vitamin C beneficial in combatting cold symptoms and improving overall health.
Based on user reviews, many individuals have found that combining this vitamin C supplement with other supplements can enhance their ability to tackle common cold symptoms. One user indicated that they experienced quicker recovery from cold symptoms when taking larger doses of the supplement, suggesting that higher amounts can be particularly effective during illness Read Review. Another reviewer reinforced this notion by stating that this vitamin C product is their go-to for fighting off the common cold, indicating a preference for it during respiratory infections Read Review.
Additionally, some users have noted the significance of consistent intake and pairing vitamin C with bioflavonoids for better absorption and immune support Read Review. However, one user did mention experiencing heartburn as a side effect of using the natural form of vitamin C, highlighting that individual responses to the supplement can vary significantly Read Review. Overall, many reviews emphasize that this vitamin C supplement can be particularly beneficial for immune health and cold prevention when integrated thoughtfully with other health products.
When it comes to treating the common cold, research suggests that a daily dose of 1 gram (1,000 mg) or more of vitamin C can significantly reduce the severity of symptoms by about 15%. This effect appears more pronounced in those experiencing more intense symptoms, making it a potential ally for those who tend to suffer during cold season [2]. For individuals who engage in heavy physical activity, higher doses, particularly ranging from 6 to 8 grams, taken at the onset of symptoms, may shorten the duration of the cold and alleviate symptoms more effectively than lower doses [1].
It's important to note, however, that while vitamin C can help with symptom management, it does not universally prevent colds in the general population. Rather, the benefits are observed more distinctly in those facing physical stresses or engaging in strenuous activities. Therefore, for those looking to ease their cold symptoms, considering a higher dosage, especially at the first sign of illness, may be worthwhile, provided it aligns with personal health considerations and advice from a healthcare professional [4].
9
Cold relief observed
2 people found this helpful
Excellent product! It's gentle on my stomach, and I've noticed relief from the symptoms of the common cold, as well as an overall improvement in my health.
7.5
Good even fasting
2 people found this helpful
Whole food-based supplements are good even on an empty stomach. They don’t upset my stomach. When feeling run down due to the common cold, I find they help with quicker recovery, especially when taken in larger amounts.
9
Essential for immunity
This vitamin C is excellent! It's essential during cold and flu season and for daily immune boosts. It doesn’t upset my sensitive stomach and tastes fine.
4
Vitamin C importance
59 people found this helpful
I am familiar with ascorbic acid, or vitamin C, since childhood. It's crucial for treating the common cold and strengthening blood vessels. Since vitamin C doesn't store well in our body, we must consume it regularly. Synthetic vitamin C is inferior, as it's not assimilated effectively. It leads to health issues and only 1-5% gets digested. For better absorption, vitamin C should be paired with bioflavonoids. Daily intake for healthy adults is 75-150 mg, with a maximum of 500 mg to avoid problems. It's beneficial to split doses throughout the day for optimal effectiveness.
9
Prevention method
1 people found this helpful
I switched to Mega Foods' vitamin C, extracted from food, years ago. I believe this has helped me avoid catching colds and stay healthy. It's beneficial for my skin, too.
7.5
Reliable choice
Mega Foods products inspire confidence. This vitamin C offers a good time release, and since I've started using it, I don't catch colds anymore.
9
Immunity booster
It's fantastic and raises immunity against the common cold and flu effectively.
2
Heartburn issue
Natural vitamin C hasn't worked well for me; it causes heartburn. I tried taking it during a common cold when I was exhausted.
7.5
Potent formula
This whole food formula is potent in one tablet. It’s my go-to for fighting the common cold.
We investigated how vitamin C affects the common cold, focusing on its potential for prevention and treatment. Research indicates that while vitamin C does not prevent colds in the general population when taken at doses over 1 g/day, it has been beneficial for individuals engaging in heavy physical activity, effectively halving their incidence of colds.
Looking into regular supplementation, we found that taking 1 g or more daily can reduce the severity of colds by about 15%. However, when it comes to starting vitamin C after cold symptoms begin, results are less consistent, though higher doses of 6-8 g/day did significantly shorten the duration of colds compared to lower doses.
Interestingly, historical studies showed that vitamin C might prevent pneumonia in specific populations, such as schoolboys or soldiers, but this doesn’t translate to the general public. While some trials indicated potential benefits for pneumonia patients, the evidence is not conclusive.
Overall, we see that given the evidence supporting reduced severity and duration of colds, along with its safety and affordability, it may be worth considering a higher dose of vitamin C for those looking to manage cold symptoms better.
8
Vitamin C reduces cold severity
Vitamin C reduces the severity of common colds: a meta-analysis.
We explored how vitamin C affects the severity of common colds through a comprehensive review of available studies. By including only randomized, placebo-controlled trials where participants received at least 1 gram of vitamin C daily, we aimed to investigate both the overall duration of colds and the intensity of symptoms experienced.
Our analysis found that vitamin C significantly reduced the severity of cold symptoms by about 15%. Interestingly, it appears that the benefits are more pronounced for those experiencing severe symptoms compared to mild ones. In specific comparisons, vitamin C didn’t substantially affect the duration of mild symptoms but had a notable impact on how long severe symptoms lasted.
This insight is crucial, as the common cold often leads to absenteeism at work and school, with more severe symptoms playing a key role in this setback. By highlighting vitamin C's greater effectiveness against intense cold symptoms, we suggest that future research should continue to look into how this vitamin can be utilized in managing cold severity.
8
Vitamin C reduces cold incidence
Vitamin C supplementation reduces the odds of developing a common cold in Republic of Korea Army recruits: randomised controlled trial.
We conducted an insightful study to explore whether vitamin C supplementation can help reduce the incidence of common colds among Republic of Korea Army recruits. Our research involved a rigorous randomised, placebo-controlled trial that included 1,444 soldiers over a 30-day period.
In this study, we divided the participants into two groups: one received a daily dose of 6,000 mg of vitamin C while the other received a placebo with no vitamin C. We investigated the soldiers' medical records to see how many of them contracted a cold during the training period.
Our findings showed encouraging results. The group that took vitamin C had a 20% lower risk of developing a common cold compared to those who took the placebo. Interestingly, this protective effect was especially pronounced among recruits in certain training camps, as well as never smokers and those who were physically ranked at level three.
Overall, we observed that vitamin C supplementation appears to be an effective strategy for reducing the incidence of common colds in military settings, which may lead to considerations for implementing vitamin C provisions during basic training for soldiers.
5
Vitamin C's varied effects on colds
Potential Role of Vitamins and Zinc on Acute Respiratory Infections Including Covid-19.
We explored the role of Vitamin C in managing common cold symptoms through a review of existing studies. The focus was to understand whether this popular vitamin could help in reducing the incidence of the common cold or its severity.
Our findings revealed that Vitamins C, D, and E did not notably lower the incidence of the common cold in the general population. However, we did discover something interesting: Vitamin C appeared to be beneficial in individuals experiencing physical or environmental stress, reducing the incidence of the cold by half in those specific circumstances.
Moreover, while Vitamin C did not prevent colds, it did play a role in shortening their duration and minimizing the severity of symptoms. On the other hand, large doses of Vitamin A showed no effects on pneumonia recovery, and Zinc had some benefits for children under five, particularly in improving clinical deterioration.
Despite the inconclusive results regarding Vitamin C and overall cold prevention, it seems that taking this vitamin during stressful periods may still offer some advantages. Overall, while the results are mixed, there's potential for Vitamin C to be a helpful component in managing colds for specific groups.
8
Vitamin C's potential benefits highlighted
Bias against Vitamin C in Mainstream Medicine: Examples from Trials of Vitamin C for Infections.
We assessed the longstanding debate about vitamin C’s effectiveness in treating the common cold. This exploration reveals that evidence has consistently indicated that vitamin C can indeed help reduce the duration and severity of cold symptoms in certain circumstances.
However, despite this evidence, mainstream medicine has often favored what we call eminence-based medicine, relying on influential figures rather than empirical data. The skepticism surrounding vitamin C largely traces back to three pivotal studies published in 1975, two in JAMA and one in the American Journal of Medicine. These studies have shaped the narrative in textbooks and nutritional guidelines, despite exhibiting notable flaws that we carefully examined.
Furthermore, we highlighted misleading reporting in recent randomized trials and critical editorials published in JAMA regarding vitamin C. While our critique largely focuses on this journal, it reflects a broader trend across medical literature, indicating a possible bias against acknowledging the benefits of vitamin C in fighting colds.
7
Vitamin C may alleviate cold symptoms
Efficacy and safety of vitamin C in the management of acute respiratory infection and disease: A rapid review.
We explored the effects of vitamin C on common cold symptoms, particularly focusing on how it may assist in alleviating those pesky issues that come with viral respiratory infections. The research indicates that taking vitamin C, especially at the onset of symptoms, might help reduce the duration of discomfort, such as fever, chills, and chest pain.
Additionally, we noted that vitamin C could potentially reduce the severity of symptoms related to common cold-induced asthma and might decrease the need for hospital admissions in some cases. While the overall evidence about vitamin C's effectiveness isn’t exhaustive, oral consumption may provide relief for many experiencing early stages of viral infections.
However, we must emphasize that there is currently no strong evidence supporting the use of vitamin C specifically for preventing or treating COVID-19, which shares similar symptoms with typical respiratory infections. Therefore, while vitamin C appears beneficial for common cold symptoms, further high-quality research is essential to validate its efficacy and safety unequivocally.
References
Hemilä H, Chalker E. Vitamin C for the common cold and pneumonia. Pol Arch Intern Med. 2025;135. doi:10.20452/pamw.16926
Hemilä H, Chalker E. Vitamin C reduces the severity of common colds: a meta-analysis. BMC Public Health. 2023;23:2468. doi:10.1186/s12889-023-17229-8
Hemilä H, Chalker E. Bias against Vitamin C in Mainstream Medicine: Examples from Trials of Vitamin C for Infections. Life (Basel). 2022;12. doi:10.3390/life12010062
Murni IK, Prawirohartono EP, Triasih R. Potential Role of Vitamins and Zinc on Acute Respiratory Infections Including Covid-19. Glob Pediatr Health. 2021;8:2333794X211021739. doi:10.1177/2333794X211021739
Ran L, Zhao W, Wang H, Zhao Y, Bu H. Vitamin C as a Supplementary Therapy in Relieving Symptoms of the Common Cold: A Meta-Analysis of 10 Randomized Controlled Trials. Biomed Res Int. 2020;2020:8573742. doi:10.1155/2020/8573742
Schloss J, Lauche R, Harnett J, Hannan N, Brown D, et al. Efficacy and safety of vitamin C in the management of acute respiratory infection and disease: A rapid review. Adv Integr Med. 2020;7:187. doi:10.1016/j.aimed.2020.07.008
Kim TK, Lim HR, Byun JS. Vitamin C supplementation reduces the odds of developing a common cold in Republic of Korea Army recruits: randomised controlled trial. BMJ Mil Health. 2022;168:117. doi:10.1136/bmjmilitary-2019-001384