The spread of misinformation has accompanied the coronavirus pandemic, including topics such as immune boosting to prevent COVID-19. This study explores how immune boosting is portrayed on the internet during the COVID-19 pandemic. The researchers compiled a dataset of 227 webpages from Google searches in Canada and the USA using the phrase ‘boost immunity’ AND ‘coronavirus’ on 1 April 2020. They coded webpages for typology and portrayal of immune boosting and supplements. They recorded mentions of microbiome, whether the webpage was selling or advertising an immune boosting product or service, and suggested strategies for boosting immunity.
No significant differences were found between webpages that appeared in the searches in Canada and the USA. The most common types of webpages were from:
- news (40.5%),
- commercial (24.7%) websites.
The concept of immune boosting was portrayed as beneficial for avoiding COVID-19 in 85.5% of webpages and supplements were portrayed as beneficial in 40% of the webpages, but commercial sites were more likely to have these portrayals. The top immune boosting strategies were:
- vitamin C (34.8%),
- diet (34.4%),
- sleep (34.4%),
- exercise (30.8%),
- zinc (26.9%).
Less than 10% of the webpages provide any critique of the concept of immune boosting.
The authors concluded that pairing evidence-based advice for maintaining one’s health (eg, healthy diet, exercise, sleep) with the phrase immune boosting and strategies lacking in evidence may inadvertently help to legitimise the concept, making it a powerful marketing tool. Results demonstrate how the spread of misinformation is complex and often more subtle than blatant fraudulent claims.
The authors did not search for evidence to check whether any of the named interventions have any influence on the immune system. As reported previously, this review did just that. Its authors aimed to evaluate evidence from clinical trials that studied nutrition-based interventions for viral diseases (with special emphasis on respiratory infections). Studies were considered eligible if they were controlled trials in humans, measuring immunological parameters, on viral and respiratory infections. Clinical trials on vitamins, minerals, nutraceuticals and probiotics were included.
A total 43 studies met the inclusion criteria:
- vitamins: 13;
- minerals: 8;
- nutraceuticals: 18
- probiotics: 4
Among vitamins, A and D showed a potential benefit, especially in deficient populations. Among trace elements, selenium and zinc have also shown favourable immune-modulatory effects in viral respiratory infections. Several nutraceuticals and probiotics may also have some role in enhancing immune functions. Micronutrients may be beneficial in nutritionally depleted elderly population.
There were 15 studies with a high score for methodological quality. Here is what their results showed:
- No significant difference in incidence of winter-time upper respiratory tract infection in children with high versus low dose vitamin D.
- Significantly less acute respiratory infections in elderly individuals with vitamin D versus placebo.
- Higher TGFbeta plasma level in response to influenza vaccination but no improved antibody response in elderly, vitamin D-deficient individuals with vitamin D versus placebo.
- No effect on lower respiratory tract infections; however, a protective effect was noted on upper respiratory tract infections in elderly individuals with vitamin E versus placebo.
- Neither daily multivitamin + mineral supplementation at physiological dose nor 200 mg of vitamin E showed a favourable effect on incidence and severity of acute respiratory tract infections in well-nourished, non- institutionalized elderly individuals.
- Better improvement in the clinical status, respiratory rate and oxygen saturation in children suffering from pneumonia with zinc sulphate versus placebo.
- Selenium-yeast increased Tctx-antibody-dependent cellular cytotoxicity cell counts in blood before flu vaccination + dose-dependent increase in T cell proliferation, IL-8 and IL-10 secretion after in vivo flu challenge in healthy volunteers.
- Frequency and duration of acute respiratory infections during the first two months was unaffected in healthy elderly with ginseng versus placebo.
- Broccoli sprout homogenate favourably affected immunological variables in healthy volunteers.
- The incidence of illness was not reduced, however significantly fewer symptoms were reported and the proliferation index of gd-T cells in culture was almost five times higher after 10 weeks of cranberry polyphenol supplements versus placebo.
- Higher antibody titres against all 3 strains contained in the seasonal influenza virus vaccine than the placebo in healthy elderly individuals with a sea-weed extract versus placebo.
- Non-inferiority was demonstrated for Echinacea compared to oseltamivir in early treatment of clinically diagnosed and virologically confirmed influenza virus infections.
- Significant reduction of cold duration and severity in air travellers with elderberry supplement versus placebo.
- Increased NK cell activity with probiotics versus placebo in tube-fed elderly patients.
- Titres against the influenza B strain increased significantly more with probiotics compared to placebo in healthy elderly individuals.