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Supplementary benefits?

The Covid-19 pandemic has raised awareness of the protective role of nutritional supplements on immune function.

The Covid-19 pandemic has raised awareness of the protective role of nutritional supplements on immune function

Learning objectives

After reading this feature you should be able to: 

  • Discuss the post-Covid immune function health claims being made for a range of vitamins and minerals
  • Explain the latest thinking regarding probiotics and prebiotics and the gut microbiome
  • Describe the new guidance on iron deficiency anaemia. 

Health benefits

The European Food Safety Authority (EFSA) recognises immune function health claims for a range of vitamins and minerals. Vitamins A (including beta-carotene), B6, folate, B12, C and D, and the minerals zinc, selenium, iron and copper may all make such claims on product labels. 

A 2020 paper published by Professor Philip Calder (Faculty of Medicine, University of Southampton) and co-authors1 made reasoned recommendations for intakes of selected nutrients (higher than reference values) to support optimal immune function. A panel of doctors and academics working with the Swiss Nutrition Society also came up with similar2 (see Table 1 below). 

Of note is that a multivitamin/mineral product providing 100 per cent of the RDA for a wide variety of micronutrients is the baseline of Calder’s recommendations. A 2021 systematic review (33 studies) and meta-analysis (19 studies) from Singapore University found a protective effect of 'non-deficiency' of specific micronutrients for Covid-19. Where there was no deficiency of vitamin D or zinc, the incidence of Covid was lowered by 63 per cent. 

In patients with Covid-19, the absence of micronutrient deficiency also provided some protection against mortality, hospitalisation, progression to serious respiratory complications and ICU admissions, although these findings were not statistically significant. The UK National Diet and Nutrition Survey continues to show below Lower Reference Nutrient Intakes for a range of vitamins and minerals as well as low blood levels of vitamin D. 

Among vitamins and minerals, vitamin D has perhaps had the highest profile during the pandemic. Poor vitamin D status, which is common in the UK, is associated with many features of poor immune function. It increases the risk of respiratory tract infections3,4 and has been associated with increased risk and severity of Covid-19. The most recent UK National Diet and Nutrition Survey data (NDNS) shows that 16 per cent of adults aged 19-64 years (18 per cent of women, 15 per cent of men), have 25-OHD plasma levels below 25nmol/litre (the UK threshold indicating deficiency).5 

While a Cochrane analysis published in May this year concluded that evidence is insufficient – often because of poor quality studies – to justify vitamin D supplementation to treat Covid-19, the review noted that 21 studies were ongoing. In the meantime, there are several calls (in addition to those highlighted in Table 1) from academics for vitamin D guidelines to be updated to take account of the vitamin’s role in immune function and the impact of deficiency on risk of respiratory tract infection. 

These include a letter from 220 scientists from the US, the UK and Europe calling for vitamin D supplementation of 50-100mcg for healthy adults. The Irish Government is developing policy for 2022 which may recommend 20-25mcg vitamin D daily. Of note is that the UK Government recommends 10mcg vitamin D daily on the basis of bone and muscle health. However, for healthy adults wanting to take a higher dose of vitamin D for immune health, the daily dose should not exceed the upper level of 100mcg. 

Covid's impact on attitudes to health

A survey of over 1,000 adults commissioned by the Health Supplements Information Service (HSIS) found that the Covid-19 pandemic had made almost three-quarters (73 per cent) more aware of their health and wellbeing, with just over half of participants (51 per cent) saying they had improved their diet since the pandemic started. 

Four in 10 (41 per cent) had thought more about their immune health, 54 per cent believed they ought to do something about it, while 35 per cent of people taking vitamin D had started to do so during the pandemic. 

Probiotics and prebiotics

Probiotics and prebiotics are becoming more popular because of the focus on the gut micro-biome. The health of the gut microbiome (i.e. the proportion of healthy to less healthy bacteria in the gut) is increasingly linked not only with the health of the gastrointestinal tract and GI diseases but also with cognitive and mental health (e.g. depression and anxiety), cardiovascular health, immune function and body weight. 

Evidence that the gut microbial population can be shifted with probiotics and prebiotics is increasing. Probiotics are live bacteria and yeasts that, when administered in viable forms and adequate amounts, are beneficial to human health; they are usually added to yoghurts or supplements and are also available in traditionally fermented foods like kefir and sauerkraut. 

Prebiotics are defined as substrates selectively used by host microorganisms conferring a health benefit; they are often described as “microbiota accessible carbohydrates” or fermentable dietary fibre. Examples of foods containing prebiotics include apples, artichokes, asparagus, bananas, barley, chicory, cocoa and tea. 

Synbiotics contain a mixture of prebiotics and probiotics. Prebiotic supplements often contain chicory and/or inulin. There is some evidence to suggest that a mix of prebiotics and probiotics may be most beneficial in shifting the gut microbial population in a healthy direction. 

The European Food Safety Authority (EFSA) does not allow the terms probiotic or prebiotic to appear on product labels as it deems these words to be health claims but, earlier this year, 22 per cent of EU member states allowed the term probiotic and 33 per cent prebiotic going against EFSA opinion. The principle of mutual recognition allows goods marketed legally in one EEA country to be marketed in another, so if member states continue on this path, it may bring about legislative change on a European level. This could be an opportunity for UK industries to be innovative and put a case forward to allow the term probiotic/prebiotic. 

The latest British Society of Gastroenterology (2021) guidelines support probiotic use in irritable bowel syndrome (IBS) for overall symptoms and more specifically for pain, but they say it is not possible to recommend a specific species or strain. Patients wishing to try probiotics should take them for up to 12 weeks and discontinue them if there is no improvement in symptoms. 

Iron deficiency anaemia

The British Society for Gastroenterology has updated its guidelines on the treatment of iron deficiency in adults. One of the recommendations is that iron salts should be given in smaller doses and less frequently than previously advised. 

The guidance cites studies of iron depleted women which have shown that oral doses of 60mg iron stimulate the increase of hepcidin (an important inhibitor of iron absorption) for the next 24 hours reducing subsequent iron absorption by 35-45 per cent. 

As a consequence the overall absorption of iron from a single 60mg daily dose was the same as that from 60mg twice a day. The authors also reference findings showing that low oral iron doses (15mg daily) are as effective as doses of 50-100mg daily in older people with iron deficiency anaemia and without causing adverse effects. 

The authors explain that giving too much iron too frequently causes gastrointestinal mucosal iron block reducing absorption of iron. The recommendation is to give a once-daily dose of 50-100mg elemental iron (e.g. one 200mg ferrous sulphate tablet each day). 

Splitting the dose means that iron is not so well absorbed from the second dose and is more likely to cause GI side-effects.

Health perfectionism, Covid, anxiety and natural remedies

A new report has revealed the pressures of 'health perfectionism' in the wake of the Covid pandemic as the UK strives to get its health and wellbeing back on track. 

Entitled “How to Be You and Fight the Post-Covid Pressures for Health Perfection”, the report from Dragonfly CBD reveals that stress, poor sleep and pain levels are on the rise as people attempt to diet and exercise themselves back to good health, but often doing too much too soon.

According to a poll conducted for the report, nearly six in 10 people feel their lives are more stressful since the pandemic began, with one in five having more trouble sleeping and a third feeling their pain levels are worse. Work is worrying four in 10 people (42 per cent), money concerns are on the minds of 40 per cent, and catching Covid and weight gain are worries for 34 per cent and 29 per cent of the population respectively – perhaps understandably as four in 10 adults gained at least half a stone during the various lockdowns.

However, instead of following a sensible eating and exercise regime to take off any Covid weight slowly, the Dragonfly CBD poll shows people are setting themselves unrealistic targets. Almost half (47 per cent) say they feel pressure to be perfect; 28 per cent feel pushed to look a certain way; one in five think they need to aspire to be an ideal partner; and the same proportion (20 per cent) want to be perfect at work.

With anxiety levels on the rise as well – some 48 per cent of people feel more stressed than they did a year ago – what can community pharmacy teams offer to help? According to Hampshire pharmacist Sultan 'Sid' Dajani, seeking remedies for anxiety and stress can be typically time-intensive and often involve long NHS waiting times. "However, there are solutions to purchase over the counter, such as CBD oils that help to reduce the negative effects associated with stress and anxiety," he points out. 

The 'How to Be You' report found that 62 per cent of respondents would prefer to try a safe, natural remedy to reduce their stress levels, so CBD oil could fit the bill as studies have shown that it can help with conditioned fear and anxiety. Dragonfly CBD products are all THC-free and independently tested for quality and safety.


Botanicals/herbal ingredients have, not surprisingly, become a focus of research during the pandemic as several have an impact on the immune system. A 2020 paper published by authors from 10 countries, including the UK, documented improved immune function effects with a range of herbs including Boswellia species, curcumin, echinacea, liquorice, and various salicylate drugs of botanical origin including willow, meadowsweet, birch and wintergreen. 

The authors concluded that these botanicals might be sources of active antiviral ingredients but that research is needed. Data do not strongly evidence their use in prevention of infection but pharmacy customers can be advised to try them if they so wish, depending on potential drug interactions as many botanicals have the capacity to interfere with the cytochrome P450 enzymes in the liver. 


Ashwagandha is a herb that is heavily promoted as an adaptogen. Theoretically, adaptogens are thought to help the body deal with physical and psychological stress. 

There is some evidence that ashwagandha helps with perceived stress. Specific standardised preparations have been used in studies in doses of up to 1,000mg daily for 12 weeks. Ashwagandha appears safe at these doses but safety data are sparse concerning the use of higher doses. 

Theoretically, ashwagandha could increase the effects of all sedative medications and might increase the risk of hypoglycaemia and hypotension with antidiabetes and antihypertensive medications. 

In terms of new research, a recently published eight-week randomised controlled trial in 100 women suggested that ashwagandha root 300mg twice daily could improve mild to moderate menopausal symptoms. 

Omega-3 fatty acids

A key role for omega-3 supplementation remains bridging the dietary gap between the actual and recommended intakes. Oily fish is the main dietary source. Among 11-18-year-olds oily fish intake is 21g weekly and in adults is only 56g weekly. These intakes are substantially lower than the recommended 140g weekly. 

Recent research from Sweden (2021) evaluated the impact of omega-3 fatty acid supplementation on cognitive function. While not a new concept, this study was groundbreaking in the novel biomarkers in cerebrospinal fluid (CSF) that it measured. The researchers also evaluated the correlation between these markers and cognitive function. 

While memory function in the people who received the supplements remained stable compared with those in the placebo group whose memory function fell, these changes were not linked to the changes in CSF biomarkers. 

Retail Brief: Bassetts Vitamins

Bassetts Vitamins and the Royal College of Obstetricians and Gynaecologists (RCOG) have joined forces to highlight good maternal nutrition during pregnancy, with Bassetts launching Bassetts Vitamins Pregnancy containing multivitamins, multiminerals and omega-3 DHA oil. The partnership will include educational content for pregnant women and healthcare professionals, highlighting the particular importance of folic acid and vitamin D during pregnancy. 


  1. Optimal nutritional status for a well-functioning immune system report
  2. Strengthining immunity report 
  3. Jolliffe DA, Camargo CA, Jr., Sluyter JD, Aglipay M, Aloia JF, Ganmaa D et al (2021) Vitamin D supplementation to prevent acute respiratory infections: a systematic review and meta-analysis of aggregate data from randomised controlled trials. Lancet Diabetes Endocrinol
  4. Martineau AR, Jolliffe DA, Hooper RL, Greenberg L, Aloia JF, Bergman P, et al (2017) Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. BMJ i6583
  5. NatCen Social Research (2020) National Diet and Nutrition Survey. Rolling programme Years 9 to 11 (2016/2017 to 2018/2019). A survey carried out on behalf of Public Health England and the Food Standards Agency, 2020 
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