Last update
3/24/2026

Overview

SCIENTIFIC SCORE
Questionable
Based on 17 Researches
6.9
USERS' SCORE
Good
Based on 16 Reviews
8.2
Supplement Facts
Serving Size:  3 Caplets
Amount Per Serving
%DV
Vitamin D (as D3 Cholecalciferol)
15 mcg (600 IU)
75%
Calcium  (as Calcium Carbonate and Calcium Gluconate)
1,000 mg
77%
Magnesium  (as Magnesium Oxide and Magnesium Gluconate)
400 mg
95%
Zinc (as Zinc Gluconate and Zinc Citrate)
25 mg
227%
Sodium
10 mg
<1%
📅 Last updated:

Top Medical Research Studies

8
Vitamin D reduces flu risk
We explored the potential benefits of vitamin D supplementation for reducing the risk of influenza infections. Through a comprehensive analysis of multiple Randomized Controlled Trials (RCTs), we aimed to clarify whether taking vitamin D can help prevent the flu.

Our investigation identified 10 relevant trials that included a total of 4,859 participants. These studies varied in their dosages and duration of vitamin D use, allowing us to assess overall effectiveness across different populations.

The findings were encouraging: our analysis demonstrated that vitamin D supplementation appears to significantly reduce the risk of getting influenza, suggesting that those who increase their vitamin D intake might be better protected during flu season.

Importantly, we did not find significant differences between the studies that could affect our result, and there was no hint of publication bias. Consequently, we can confidently suggest that including vitamin D in our health strategies could enhance our defenses against the flu.
Read More
We investigated whether high-dose vitamin D supplementation could lessen cold and flu symptoms in preschool children. Conducted in Toronto, this study involved over 700 children aged 1 to 5, who received either a high dose of 2000 IU or a standard dose of 400 IU for one winter season.

Despite hopes that higher doses would help, our findings showed no significant reduction in the severity of upper respiratory tract infections, outpatient visits, emergency room visits, or the need for antibiotics compared to the standard dose.

Ultimately, taking more vitamin D than recommended doesn’t seem beneficial for alleviating flu symptoms in kids.
Read More
8
Vitamin D3 reduces flu-like illnesses
We conducted a practical study to investigate how daily vitamin D3 supplementation at 5000 IU might help reduce flu-like illnesses in healthcare workers. This was especially important during the COVID-19 pandemic, where preventing viral infections is crucial for those on the front lines.

Our study involved 255 healthcare workers who received the vitamin D3 supplement for at least two months and compared them to a control group of 2827 workers who did not receive the supplement. We asked participants to monitor themselves for any flu-like symptoms and report for COVID-19 testing accordingly.

The results were promising; those supplementing with vitamin D experienced a significant reduction in the incidence of flu-like illnesses. The numbers showed a noteworthy drop in non-COVID-19 flu-like illness rates among those taking the supplement. However, when it came to COVID-19 related flu-like illnesses, the difference was not statistically significant.

Overall, our exploration of vitamin D3's effects suggests that it may be a beneficial addition to the health routines of healthcare workers to stave off flu-like illnesses, although its influence on COVID-19 specifically requires further investigation.
Read More

Most Useful Reviews

10
Never sick again
I never get sick anymore after consuming this vitamin—no flu or cough. Thanks!
Read More
9
Cramps relief
I’ve been using this for nearly two years, and I used to experience cramps daily. Now, I no longer have cramps, and my immune system feels stronger against seasonal flu.
Read More
9
Pandemic immunity
I’ve taken zinc since the beginning of the pandemic to boost my immune system. It’s a crucial mineral for our bodies. I believe it works because I haven’t caught flu in the last two years.
Read More

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Medical Researches

SCIENTIFIC SCORE
Questionable
Based on 17 Researches
6.9
  • All Researches
9
Vitamin D enhances influenza defenses
We recently examined how vitamin D impacts our body's response to influenza H1N1, an important viral infection. Utilizing 142 clinical cases from the Department of Otolaryngology at Sun Yat-sen University, we dug into the effects of vitamin D deficiency on chronic rhinosinusitis (CRS), a condition that frequently involves damage to the airway's lining. By studying airway organoids treated with vitamin D, we were able to simulate how this treatment might bolster our defenses against flu viruses and bacteria like Staphylococcus aureus.

Our observations showed that many patients with CRS suffered from vitamin D deficiency. Notably, those who received vitamin D treatment exhibited faster cell growth in the nasal epithelium. When exposed to the H1N1 virus, these treated organoids demonstrated a remarkable ability to fend off the infection better than those without vitamin D. This protection stemmed from enhancements in host defenses, including improved production of antimicrobial proteins, reduced inflammation, and better epithelial integrity—crucial factors in fighting off infections.

We also uncovered some fascinating insights about the biological mechanisms at work. Vitamin D seemed to actively influence how epithelial cells develop and repair themselves while managing immune responses against infections. These findings underscore the significance of addressing vitamin D deficiency, especially for those vulnerable to respiratory illnesses.
Read More
We investigated the potential of zinc in combination with herbal polyphenols and copper to reduce the infectivity of respiratory RNA viruses, including the flu. This study is particularly timely due to the ongoing challenges posed by viruses like SARS-CoV-2, highlighting the need for effective therapeutic solutions.

Zinc ions are known to play a role in modulating viral RNA replication, which makes them an appealing option for decreasing viral loads and infectivity. However, a significant challenge is that the natural concentration of zinc in our cells is often too low for effective results. To tackle this, we combined zinc picolinate, a form of zinc that’s easier for the body to absorb, with a range of flavonoids—natural compounds renowned for their antioxidant properties and existing antiviral effects.

We ensured that these combinations were safe by assessing their impact on cultured cells, confirming that they didn’t harm cell viability. When tested further, our results revealed an impressive 50-95% reduction in viral genome replication levels across a variety of respiratory RNA viruses, including the flu virus, which suggests that this combination therapy could be promising in the fight against such illnesses.

Overall, our findings highlight an innovative approach to treating viral infections that is non-toxic, derived from nature, and may remain effective against emerging viral strains.
Read More
We explored how vitamin D supplementation might help reduce the risk of respiratory infections, particularly the flu, in care homes. Our systematic review of several randomized controlled trials focused on interventions to reduce the transmission of acute respiratory infections, looking beyond just vaccines.

Our findings highlighted that high-dose vitamin D supplementation led to a significant decrease in the incidence of acute respiratory infections, reducing the likelihood of getting sick. Specifically, one trial indicated a 40% reduction in these infections among participants receiving vitamin D compared to those who did not.

However, not all studies we reviewed showed compelling results for related supplements like vitamins, minerals, probiotics, and herbal aids, which did not significantly impact infection rates. This means that while vitamin D supplementation shows promise, more research is needed to fully understand its effects and confirm its benefits in combating flu and other respiratory illnesses.
Read More
8
Vitamin D3 reduces flu-like illnesses
We conducted a practical study to investigate how daily vitamin D3 supplementation at 5000 IU might help reduce flu-like illnesses in healthcare workers. This was especially important during the COVID-19 pandemic, where preventing viral infections is crucial for those on the front lines.

Our study involved 255 healthcare workers who received the vitamin D3 supplement for at least two months and compared them to a control group of 2827 workers who did not receive the supplement. We asked participants to monitor themselves for any flu-like symptoms and report for COVID-19 testing accordingly.

The results were promising; those supplementing with vitamin D experienced a significant reduction in the incidence of flu-like illnesses. The numbers showed a noteworthy drop in non-COVID-19 flu-like illness rates among those taking the supplement. However, when it came to COVID-19 related flu-like illnesses, the difference was not statistically significant.

Overall, our exploration of vitamin D3's effects suggests that it may be a beneficial addition to the health routines of healthcare workers to stave off flu-like illnesses, although its influence on COVID-19 specifically requires further investigation.
Read More
8
Vitamin D reduces flu risk
We explored the potential benefits of vitamin D supplementation for reducing the risk of influenza infections. Through a comprehensive analysis of multiple Randomized Controlled Trials (RCTs), we aimed to clarify whether taking vitamin D can help prevent the flu.

Our investigation identified 10 relevant trials that included a total of 4,859 participants. These studies varied in their dosages and duration of vitamin D use, allowing us to assess overall effectiveness across different populations.

The findings were encouraging: our analysis demonstrated that vitamin D supplementation appears to significantly reduce the risk of getting influenza, suggesting that those who increase their vitamin D intake might be better protected during flu season.

Importantly, we did not find significant differences between the studies that could affect our result, and there was no hint of publication bias. Consequently, we can confidently suggest that including vitamin D in our health strategies could enhance our defenses against the flu.
Read More

User Reviews

USERS' SCORE
Good
Based on 16 Reviews
8.2
  • All Reviews
  • Positive Reviews
  • Negative Reviews
10
Never sick again
I never get sick anymore after consuming this vitamin—no flu or cough. Thanks!
Read More
9
Cramps relief
I’ve been using this for nearly two years, and I used to experience cramps daily. Now, I no longer have cramps, and my immune system feels stronger against seasonal flu.
Read More
9
Pandemic immunity
I’ve taken zinc since the beginning of the pandemic to boost my immune system. It’s a crucial mineral for our bodies. I believe it works because I haven’t caught flu in the last two years.
Read More
9
Strengthened immunity
I took these vitamins for children, and they performed exceptionally well during the autumn-winter period. Thanks to the boosted immunity, we did not suffer from the flu.
Read More
9
Effective against flu
This is the best collection of vitamin C, zinc, and magnesium. It is very effective against the flu and corona, and the price at IHERB is excellent.
Read More

Frequently Asked Questions

7.5
Affordable prevention
This complex is essential in times when flu viruses are rampant. It can be taken for prevention and during influenza treatment. I really appreciate the vitamins from this brand, and the price is affordable.
10
Never sick again
I never get sick anymore after consuming this vitamin—no flu or cough. Thanks!
7.5
Flu prevention
The package arrived intact, and I really like the composition and taste. It effectively eliminates deficiencies quickly. I take it periodically in the autumn when flu season starts, alongside vitamin C. I’m satisfied with the results.
7.5
Quality supplements
During flu season, I try to give my family zinc-containing supplements. This combination of calcium, magnesium, zinc, and D3 is excellent for our health. I recommend taking such supplements at least twice a year. Nature's Bounty capsules are of good quality and easily swallowed.
8
Vitamin D reduces flu risk
We explored the potential benefits of vitamin D supplementation for reducing the risk of influenza infections. Through a comprehensive analysis of multiple Randomized Controlled Trials (RCTs), we aimed to clarify whether taking vitamin D can help prevent the flu.

Our investigation identified 10 relevant trials that included a total of 4,859 participants. These studies varied in their dosages and duration of vitamin D use, allowing us to assess overall effectiveness across different populations.

The findings were encouraging: our analysis demonstrated that vitamin D supplementation appears to significantly reduce the risk of getting influenza, suggesting that those who increase their vitamin D intake might be better protected during flu season.

Importantly, we did not find significant differences between the studies that could affect our result, and there was no hint of publication bias. Consequently, we can confidently suggest that including vitamin D in our health strategies could enhance our defenses against the flu.
We conducted a randomized, double-blind, controlled trial to explore whether vitamin D supplementation could lower the risk of flu among young children. The study involved 248 participants aged two to five years from daycare centers in Taiwan, who were divided into two groups: one received 2000 IU of vitamin D daily, while the other group received a placebo for one month.

The results were intriguing. We found an 84% relative risk reduction for flu infection in the vitamin D group compared to the placebo group. However, this finding did not achieve statistical significance, which means we can't be certain of its importance. The data suggested that the placebo group might have a higher chance of getting the flu, but again, the results were not definitive.

Additionally, no significant differences were observed in terms of enterovirus infections between the two groups, and the same trend was seen among household members of the children. Everyone who received the vitamin D treatment managed to raise their vitamin D levels above 30 ng/ml, indicating that the supplementation was effective in boosting their vitamin D status.

Overall, while vitamin D supplementation might offer some protective effect against flu in preschoolers, the evidence does not strongly support this. We recommend further research to fully understand the impact.
9
Vitamin D enhances influenza defenses
We recently examined how vitamin D impacts our body's response to influenza H1N1, an important viral infection. Utilizing 142 clinical cases from the Department of Otolaryngology at Sun Yat-sen University, we dug into the effects of vitamin D deficiency on chronic rhinosinusitis (CRS), a condition that frequently involves damage to the airway's lining. By studying airway organoids treated with vitamin D, we were able to simulate how this treatment might bolster our defenses against flu viruses and bacteria like Staphylococcus aureus.

Our observations showed that many patients with CRS suffered from vitamin D deficiency. Notably, those who received vitamin D treatment exhibited faster cell growth in the nasal epithelium. When exposed to the H1N1 virus, these treated organoids demonstrated a remarkable ability to fend off the infection better than those without vitamin D. This protection stemmed from enhancements in host defenses, including improved production of antimicrobial proteins, reduced inflammation, and better epithelial integrity—crucial factors in fighting off infections.

We also uncovered some fascinating insights about the biological mechanisms at work. Vitamin D seemed to actively influence how epithelial cells develop and repair themselves while managing immune responses against infections. These findings underscore the significance of addressing vitamin D deficiency, especially for those vulnerable to respiratory illnesses.
8
Vitamin D3 reduces flu-like illnesses
We conducted a practical study to investigate how daily vitamin D3 supplementation at 5000 IU might help reduce flu-like illnesses in healthcare workers. This was especially important during the COVID-19 pandemic, where preventing viral infections is crucial for those on the front lines.

Our study involved 255 healthcare workers who received the vitamin D3 supplement for at least two months and compared them to a control group of 2827 workers who did not receive the supplement. We asked participants to monitor themselves for any flu-like symptoms and report for COVID-19 testing accordingly.

The results were promising; those supplementing with vitamin D experienced a significant reduction in the incidence of flu-like illnesses. The numbers showed a noteworthy drop in non-COVID-19 flu-like illness rates among those taking the supplement. However, when it came to COVID-19 related flu-like illnesses, the difference was not statistically significant.

Overall, our exploration of vitamin D3's effects suggests that it may be a beneficial addition to the health routines of healthcare workers to stave off flu-like illnesses, although its influence on COVID-19 specifically requires further investigation.

References

  1. Willcox ML, Lavu D, Yousaf U, Dalton S, Roberts N, et al. The effectiveness of interventions to reduce the transmission of acute respiratory infections in care homes: a systematic review. J Public Health (Oxf). 2024;46:551. 10.1093/pubmed/fdae178
  2. Liao S, Huang Y, Zhang J, Xiong Q, Chi M, et al. Vitamin D promotes epithelial tissue repair and host defense responses against influenza H1N1 virus and Staphylococcus aureus infections. Respir Res. 2023;24:175. 10.1186/s12931-023-02477-4
  3. van Helmond N, Brobyn TL, LaRiccia PJ, Cafaro T, Hunter K, et al. Vitamin D3 Supplementation at 5000 IU Daily for the Prevention of Influenza-like Illness in Healthcare Workers: A Pragmatic Randomized Clinical Trial. Nutrients. 2022;15. 10.3390/nu15010180
  4. Arora J, Patel DR, Nicol MJ, Field CJ, Restori KH, et al. Vitamin D and the Ability to Produce 1,25(OH)D Are Critical for Protection from Viral Infection of the Lungs. Nutrients. 2022;14. 10.3390/nu14153061
  5. Huang YN, Chi H, Chiu NC, Huang CY, Li ST, et al. A randomized trial of vitamin D supplementation to prevent seasonal influenza and enterovirus infection in children. J Microbiol Immunol Infect. 2022;55:803. 10.1016/j.jmii.2022.01.003
  6. Zhu Z, Zhu X, Gu L, Zhan Y, Chen L, et al. Association Between Vitamin D and Influenza: Meta-Analysis and Systematic Review of Randomized Controlled Trials. Front Nutr. 2021;8:799709. 10.3389/fnut.2021.799709
  7. Godan Hauptman A, Lukić-Grlić A, Vraneš J, Milošević M, Gagro A. The effect of standard-dose wintertime vitamin D supplementation on influenza infection in immunized nursing home elderly residents. Croat Med J. 2021;62:495. PubMed
  8. Abioye AI, Bromage S, Fawzi W. Effect of micronutrient supplements on influenza and other respiratory tract infections among adults: a systematic review and meta-analysis. BMJ Glob Health. 2021;6. 10.1136/bmjgh-2020-003176
  9. Slusky DJG, Zeckhauser RJ. Sunlight and Protection Against Influenza. Econ Hum Biol. 2021;40:100942. 10.1016/j.ehb.2020.100942
  10. Hueniken K, Aglipay M, Birken CS, Parkin PC, Loeb MB, et al. Effect of High-Dose Vitamin D Supplementation on Upper Respiratory Tract Infection Symptom Severity in Healthy Children. Pediatr Infect Dis J. 2019;38:564. 10.1097/INF.0000000000002225
  11. Kanellopoulou C, George AB, Masutani E, Cannons JL, Ravell JC, et al. Mg regulation of kinase signaling and immune function. J Exp Med. 2019;216:1828. 10.1084/jem.20181970
  12. Muniz FWMG, Casarin M, Pola NM, Rösing CK, Silveira TMD, et al. Efficacy of regular gargling with a cetylpyridinium chloride plus zinc containing mouthwash can reduce upper respiratory symptoms. PLoS One. 2025;20:e0316807. 10.1371/journal.pone.0316807
  13. Nishi K, Yoshimoto S, Nishi S, Nishi T, Nishi R, et al. Epipharyngeal Abrasive Therapy Down-regulates the Expression of Cav1.2: A Key Molecule in Influenza Virus Entry. In Vivo. 2022;36:2357. 10.21873/invivo.12967
  14. Kreiser T, Zaguri D, Sachdeva S, Zamostiano R, Mograbi J, et al. Inhibition of Respiratory RNA Viruses by a Composition of Ionophoric Polyphenols with Metal Ions. Pharmaceuticals (Basel). 2022;15. 10.3390/ph15030377
  15. Nakashima A, Horio Y, Suzuki K, Isegawa Y. Antiviral Activity and Underlying Action Mechanism of Euglena Extract against Influenza Virus. Nutrients. 2021;13. 10.3390/nu13113911
  16. Sadeghsoltani F, Mohammadzadeh I, Safari MM, Hassanpour P, Izadpanah M, et al. Zinc and Respiratory Viral Infections: Important Trace Element in Anti-viral Response and Immune Regulation. Biol Trace Elem Res. 2022;200:2556. 10.1007/s12011-021-02859-z
  17. Jaber R. Respiratory and allergic diseases: from upper respiratory tract infections to asthma. Prim Care. 2002;29:231. PubMed
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