The global market for dietary supplements has grown continuously during the past years. In 2019, it amounted to around US$ 353 billion. The pandemic led to a further significant boost in sales. Evidently, many consumers listened to the sly promotion by the supplement industry. Thus they began to be convinced that supplements might stimulate their immune system and thus protect them against COVID-19 infections.
During the pre-pandemic years, the US sales figures had typically increased by about 5% year on year. In 2020, the increase amounted to a staggering 44 % (US$435 million) during the six weeks preceding April 5th, 2020 relative to the same period in 2019. The demand for multivitamins in the US reached a peak in March 2020 when sales figures had risen by 51.2 %. Total sales of vitamins and other supplements amounted to almost 120 million units for that period alone. In the UK, vitamin sales increased by 63 % and, in France, sales grew by around 40–60 % in March 2020 compared to the same period of the previous year.
Vis a vis such impressive sales figures, one should ask whether dietary supplements really do produce the benefit that consumers hope for. More precisely, is there any sound evidence that these supplements protect us from getting infected by COVID-19? In an attempt to answer this question, I conducted several Medline searches. Here are the conclusions of the relevant clinical trials and systematic reviews that I thus found:
- KSK (a polyherbal formulation from India’s Siddha system of medicine) significantly reduced SARS-CoV-2 viral load among asymptomatic COVID-19 cases and did not record any adverse effect, indicating the use of KSK in the strategy against COVID-19. Larger, multi-centric trials can strengthen the current findings.
- There is currently insufficient evidence to determine the benefits and harms of vitamin D supplementation as a treatment of COVID-19.
- Herbal supplements may help patients with COVID-19, zinc sulfate is likely to shorten the duration of olfactory dysfunction. DS therapy and herbal medicine appear to be safe and effective adjuvant therapies for patients with COVID-19. These results must be interpreted with caution due to the overall low quality of the included trials. More well-designed RCTs are needed in the future.
- No significant difference with vitamin-D supplementation on major health related outcomes in COVID-19.
- there is not enough evidence on the association between individual zinc status and COVID-19 infections and mortality.
- Omega-3 supplementation improved the levels of several parameters of respiratory and renal function in critically ill patients with COVID-19.
- A 5000 IU daily oral vitamin D3 supplementation for 2 weeks reduces the time to recovery for cough and gustatory sensory loss among patients with sub-optimal vitamin D status and mild to moderate COVID-19 symptoms. The use of 5000 IU vitamin D3 as an adjuvant therapy for COVID-19 patients with suboptimal vitamin D status, even for a short duration, is recommended.
- In this 2-sample MR study, we did not observe evidence to support an association between 25OHD levels and COVID-19 susceptibility, severity, or hospitalization. Hence, vitamin D supplementation as a means of protecting against worsened COVID-19 outcomes is not supported by genetic evidence.
- These antiviral and immune-modulating activities and their ability to stimulate interferon production recommend the use of probiotics as an adjunctive therapy to prevent COVID-19. Based on this extensive review of RCTs we suggest that probiotics are a rational complementary treatment for RTI diseases and a viable option to support faster recovery.
- In this randomized clinical trial of ambulatory patients diagnosed with SARS-CoV-2 infection, treatment with high-dose zinc gluconate, ascorbic acid, or a combination of the 2 supplements did not significantly decrease the duration of symptoms compared with standard of care.
- These findings neither support nor refute the claim that 3M3F alters the severity of COVID-19 or alleviates symptoms. More rigorous studies are required to properly ascertain the potential role of Chinese Herbal Medicine in COVID-19.
- NSO (Nigella sativa oil) supplementation was associated with faster recovery of symptoms than usual care alone for patients with mild COVID-19 infection. These potential therapeutic benefits require further exploration with placebo-controlled, double-blinded studies.
- The clinical application of LQ (Lianhua Qingwen Granules or Capsules ) on the treatment of COVID-19 has significant efficacy in improving clinical symptoms and reducing the rate of clinical change to severe or critical condition. Nevertheless, due to the limited quantity and quality of the included studies, more and higher quality trials with more observational indicators are expected to be published.
- The study identified some important potential traditional Indian medicinal herbs such as Ocimum tenuiflorum, Tinospora cordifolia, Achyranthes bidentata, Cinnamomum cassia, Cydonia oblonga, Embelin ribes, Justicia adhatoda, Momordica charantia, Withania somnifera, Zingiber officinale, Camphor, and Kabusura kudineer, which could be used in therapeutic strategies against SARS-CoV-2 infection.
- Shenhuang Granule is a promising integrative therapy for severe and critical COVID-19.
- Low-certainty or very low-certainty evidence demonstrated that oral CPM (Chinese patent medicine) may have add-on potential therapeutic effects for patients with non-serious COVID-19. These findings need to be further confirmed by well-designed clinical trials with adequate sample sizes.
- XYP (Xiyanping) injection is safe and effective in improving the recovery of patients with mild to moderate COVID-19. However, further studies are warranted to evaluate the efficacy of XYP in an expanded cohort comprising COVID-19 patients at different disease stages.
- Our meta-analysis of RCTs indicated that LH (Lianhuaqingwen) in combination with usual treatment may improve the clinical efficacy in patients with mild or moderate COVID-19 without increasing adverse events. However, given the limitations and poor quality of included trials in this study, further large-sample RCTs or high-quality real-world studies are needed to confirm our conclusions.
- Reduning injection might be effective and safe in patients with symptomatic COVID-19.
- In light of the safety and effectiveness profiles, LH (Lianhuaqingwen) capsules could be considered to ameliorate clinical symptoms of Covid-19.
- QPT (Qingfei Paidu Tang) was associated with a substantially lower risk of in-hospital mortality, without extra risk of acute liver injury or acute kidney injury among patients hospitalized with COVID-19.
- This community-based RCT found that the use of a herbal medicine therapy (Jinhaoartemisia antipyretic granules and Huoxiangzhengqi oral liquids) could significantly reduce the risks of the common cold among community-dwelling residents, suggesting that herbal medicine may be a useful approach for public health intervention to minimize preventable morbidity during COVID-19 outbreak.
- Based on unresolved controversies and inconclusive findings, it could be said that generally, a single and specific therapeutics to COVID-19 is still a mirage.
- Keguan-1-based integrative therapy was safe and superior to the standard therapy in suppressing the development of ARDS in COVID-19 patients.
Does the evidence justify the boom in sales of dietary supplements?
More specifically, is there good evidence that the products the US supplement industry is selling protect us against COVID-19 infections?
No, I don’t think so.
So, what precisely is behind the recent sales boom?
It surely is the claim that supplements protect us from Covid-19 which is being promoted in many different ways by the industry. In other words, we are being taken for a (very expensive) ride.