This paper is dedicated to the indelible spirit of my Grandmother Evelyn Clapperton.
Connecting vitamin D to respiratory health appears from all my research to be a no-brainer. Vitamin D deficiency is part of my family history. My grandfather and father were separately quarantined in a sanatorium in Ontario, Canada, in the late 1930s amid a continuing epidemic of tuberculosis (TB). Imagine a young boy separated from his family and not being able to see his father in the next building. There was no welfare, and with the sole provider for the family gone, and her only child locked away, my grandmother worked as many jobs as she could to make the mortgage payments. She was determined that her young son and husband would return to their home.
This was no small task for my 4 ft 10 in and 90 lb grandmother, who had suffered from rickets as a child (a severe deficiency of vitamin D). Her soft foot bones had been squashed into too-small hand-me-down shoes causing her toes to be permanently deformed. Her feet were always painful. Being hunched over a knitting machine, from the time she was eight years old until the family immigrated to Canada from England, gave her a hunched back. Happily, despite the naysayers, my tiny grandmother made all the mortgage payments, my father returned home after six months, and my grandfather about a year later.
I ask myself, why are there adults and children in this world today with rickets, and why is TB still considered an epidemic?
In 1922, Elmer McCollum and his team at Johns Hopkins reported on a new factor from cod liver oil that cured rickets, which is a softening and then weakening of the bones primarily in children due to prolonged lack of vitamin D. They showed that an unidentified vitamin increased the amount of calcium (Ca) and phosphorus (P) deposited in bones. At the same time, a group of doctors in Austria and the UK reported that children with rickets could be cured by sunlight during summer. Then, in 1928, Windaus and Linsert announced the discovery of vitamin D.
Before this we had learned in the 1890s that sunshine could cure tuberculosis (TB) and rickets. In 1903, Dr. Neils Finsen won the Nobel Prize in Physiology or Medicine for the discovery that light therapy could cure the skin form of TB. There were large numbers of patients with consumption (TB) moving to Colorado in the late 1890s and early 1900s in hopes of being cured by the high altitude and clean dry air. None of them knew that living at high altitude also meant more exposure to UVB ( the part of the ultraviolet spectrum which causes sunburn), especially in summer, which in turn meant more vitamin D was manufactured in their skin.
Dr. Susan Anderson, a young physician from Michigan, went to the town of Fraser, Colorado just as winter hit the area in the early 1900’s to heal her consumption. She spent days sleeping next to an open sunny window, drinking hay-fed milk, and then started snowshoeing when she was strong enough. The village people remarked on her tanned face as she got stronger (Virginia Cornell, 1991). Doc Susie didn’t know about vitamins A and D but had realized that there was healing power in the high Colorado climate when combined with good nutrition. She was well known for lecturing her patients on the value of eating rhubarb and vegetables. Rhubarb is a good source of vitamins C and B, potassium (K) and manganese (Mn) and grew well in the area. Without social media and modern medicine we knew the value of nutrition and sunshine for maintaining optimum health.
I challenge all of us to use this low tech, practical, cheap, and common-sense wisdom in our high-tech world — To Be Well and Stay Well.
The science of vitamin D and respiratory wellness
Our lives have been turned upside down and inside out by a respiratory virus SARS-CoV-2 that causes COVID-19. Now we spend a lot of time thinking about ways to keep our immune system tuned-up. Many of you will know that vitamin D is used for keeping our skeletons strong. It helps bones to accumulate calcium (Ca), phosphorus (P) and magnesium (Mg) so they resist breaking and regenerate quickly.
Vitamin D has also been shown to protect against respiratory infections caused by bacteria and viruses. Getting enough vitamin D is one of the easiest and cheapest things we can all do to help our bodies stay well. Humans and animals on a sunny spring or summer day can produce all the vitamin D they need to stay healthy. The ultraviolet B (UVB) energy from sunlight transforms a universally present cholesterol (7-dihydrocholesterol) in the skin to previtamin D3, which is carried to the liver and then the kidneys to be converted into its active form we call vitamin D. Most dietary supplements are manufactured by exposing a plant sterol to ultraviolet energy, producing vitamin D2, which is almost identical to D3. Generally, both are lumped together and called vitamin D.
No one is immune to vitamin D deficiency. The biggest risk factor for vitamin D deficiency is insufficient sun exposure (Holick 2007; Holick and Chen, 2008). When the cold and flu season rolls around in late fall and winter, anyone living outside of the equator and tropics cannot eat or make sufficient Vitamin D. Your grandparents likely remember forcing down a teaspoon of the dreaded cod liver oil every day in winter. Aren’t you glad cod liver oil and vitamin D supplements are now in capsules!
I am not surprised there has been a renewed interest in the association between vitamin D and respiratory illness. Studies have recently shown significant, but in my mind tentative, correlations between low vitamin D levels and the numbers of deaths related to COVID-19 in Europe. Scandinavian countries have been among the nations with the lowest number of cases and deaths associated with COVID-19, and the highest average levels of vitamin D. There is a public health emphasis on foods fortified with vitamin D, supplements, and cod liver oil in northern Europe. In contrast, the countries of Italy and Spain have had more cases of COVID-19 and higher death rates, and on average have significantly lower levels of vitamin D, compared with the countries in northern Europe. People in the Mediterranean countries generally avoid strong sun, and their natural skin colour requires them to spend more time in the sun to make enough vitamin D.
What was also interesting for me was that people with COVID-19 in northern European countries generally recovered more quickly with fewer complications. Vitamin D dampens the proinflammatory response of our immune systems to viruses–called cytokine storm or acute respiratory distress syndrome. Of course, as a couple of studies were careful to point out, correlation does not mean causation (Ilie et al. 2020; Rhodes et al. 2020). Mitchell (2020) outlines a growing number of studies that have demonstrated strong circumstantial evidence that patients with COVID-19 are likely to have a better outcome if they are not vitamin D deficient. A common finding in almost all the studies I reviewed was that patients that entered a study deficient in vitamin D often had the worst outcomes, and responded the best to supplements.
There were a number of research and clinical studies that demonstrated a strong relationship between having adequate vitamin D and a lower risk of developing any kind of upper respiratory infection (Chang and Lee 2019, Daley et al, 2019; Rondanelli et al 2018; Martineau et al 2017; Bartley 2010). The take home message from my research is that vitamin D deficiency leads to worse health outcomes and prolonged recovery from respiratory infections. Although there is no direct evidence that vitamin D can reduce the risk of contracting COVID- 19, there is strong evidence that vitamin D reduces proinflammatory responses to diseases, and can temper cytokine storms. So, it is possible that having sufficient vitamin D could speed the recovery. This means it is imperative that we maintain adequate levels of vitamin D especially at the start of cold and flu season. Gombart et al (2020) concluded that the body needs optimal levels of micronutrients, including vitamin D, to lower the risk of infections. I can hear Doc Susie telling us all to eat well, and play outside.
How can I get enough vitamin D in winter?
It is estimated that 1 billion people worldwide have vitamin D deficiency (Holick 2007). The major cause of vitamin D deficiency is lack of moderate skin exposure to sun (Holick and Chen 2008; McCullough and Lehrer 2018). “Very few foods naturally contain vitamin D, and foods that are fortified with vitamin D are often inadequate to satisfy either a child’s or adult’s vitamin D requirement” (Holick and Chen 2008). Lifestyle changes have more and more people working indoors during the important sunlight hours (11 am until 3 pm), and midday outdoor activities for school children are often reduced. We wear sunscreen and cover up when we are in the sun. Together, this means that for most people today, vitamin D supplements will be essential to maintain wellness (Mitchell, 2020; Charoenngam et al. 2019). Pets and livestock can also suffer Vitamin D deficiency in winter leading to bone softening diseases and respiratory issues (Smith et al. 2018). They need vitamin D too.
In the Netherlands, Hochberg and Hochberg (2019) recommended children and adults leave their hands and head uncovered for 15–30 minutes daily to make a healthy dose of up to 25,000 IU (International Units) of vitamin D (Rondanelli et al 2018). People with darker skins need more sun exposure because the pigment in their skin filters the UVB. As humans moved north and south from the equator, we lost our skin tint. Only humans with light skin tones can make enough vitamin D naturally outside of the tropics (Holick 2007; Alex Bridgett 2019). Conversely, this means that light skinned people can easily get sunburn in the tropics. The risk of skin cancer from too much sun exposure is real. Health and happiness tend to be finding the balance. We need to get enough sun to make vitamin D, but not so much that we run the risk of skin cancer.
Other factors such as age, sex, diabetes, hypertension, religion, overall health, and genetics can also affect the amount of vitamin D required to maintain health. People with chronic diseases like cystic fibrosis, diabetes, obesity, and Crohn’s have compromised immune systems, an increased incidence of respiratory infections, and are known to have difficulty absorbing vitamin D (Danker et al 2019). Much of what we know about vitamin D and how it affects the immune system is from the study of chronic diseases (Tangpricha et al 2017). Both Deluca (2014) and McCullough and Lehrer (2019) have written historical reviews on the use of vitamin D to cure respiratory diseases, especially tuberculosis.
It is generally accepted that more than 30 ng/ml of vitamin D in your blood or plasma is sufficient for the maintenance of good health, while less than 20 ng/ml is considered deficient and the range in between 21 and 29 ng/ml is considered insufficient. Too much ranges from 100 and 150 ng/ml (Holick and Chen 2007; Chang and Lee 2019). The risk of too much vitamin D is greater in children than adults, and I discuss dosing levels of vitamin later on in this paper. There is some controversy over how vitamin D is measured, and when to measure, because levels can vary dramatically with medications, stress, trauma, hormones, and underlying disease (Reijen and Soeters 2020).
As you can see in Table 2, it is hard to eat your way to sufficient vitamin D, especially if you are a vegetarian or vegan. And not all variants of some foods are equal. For example, it has been shown that wild-caught salmon had on average 500 –1000 IU vitamin D in 100 g (3.5 ounces), whereas farmed salmon contained only 100 –250 IU vitamin D per 100 g serving (Holick 2007). The most likely reason is that vitamin D is plentiful in the food chain but is not as plentiful in the pelleted diet fed to the farmed salmon. Clearly diet matters.
Mushrooms and foods that are colonized by fungi – like fermented foods- can be a natural source of D2 (D2 still needs to go through the liver and the kidneys to be useful). Sun dried mushrooms are better sources of D2.
It is common to see staple foods fortified with vitamin D. These include non-dairy drinks or nut beverages, juices, flour, cereal, bread, and milk products. The amount of vitamin D may or may not be regulated or mandated depending on the country. Sun and supplements are still generally recommended to maintain a healthy immune system.
Vitamin D and how it works to maintain the body’s defence forces
The primary functions of the immune system are to protect the body against infection, contain and clear damaged tissues, and provide constant surveillance for invaders and malignant cells. The immune system has an acquired memory of the protein and chemical signatures from all the invaders it has fought and destroyed. It also has the ability to recognize and avoid attacking healthy tissue or harmless substances. We all have a different ability to fight invaders depending on genetics, environment, lifestyle and nutrition, and interactions between all these factors. It is well documented in the scientific and clinical literature that having good and adequate nutrition is closely associated with improved immunity and the ability of the body to fight infection. The European Food Safety Authority has recognized the health claims for vitamins D, C, E, and zinc (Zn) as positively affecting the immune system function for making us fit to fight.
The immune system as a whole is composed of an intricate network of highly specialized chemicals, cells, tissues and organs that are organized into three defense forces: physical barrier, innate immunity and adaptive immunity (Rondanelli et al 2018).
A barrier to entry
The first defense force is the physical barrier which includes the skin, mucus membranes, and mucus secretions (that can contain bacteria-killing peptides). Stomach acidity and the lowering of pH in body fluids can limit the growth of most bacteria. Vitamin D is important for protecting the integrity of the lining and mucus in the small intestines. People with deficient vitamin D level have leaky guts allowing for bacteria to infiltrate the mucus barrier and move freely within the intestines and sometimes into the blood. Changes in the microbial community structure within the gut can also cause leaks in the lining of the intestine allowing the deeper layers to become inflamed, which can lead to colitis, and can facilitate bacterial infections.
This process, if left unchecked, can lead to further inflammation from cytokines (proinflammatory molecules) and leave the intestines subject to deeper infections, food sensitivities and allergies, which spiral into even more and deeper inflammation. Restoring adequate levels of vitamin D stabilizes the pH balance, and Ca, P and Mg uptake, and stimulates anti-inflammatory activity reducing the incidence of Irritable Bowel Syndrome (IBS), Crohn’s disease, presence of pathogens, and bacterial infections in the colon (Kanhere et al. 2016; Dimitrov and White 2017; Rondanelli et al 2018; Malaguarnera 2020). A stable gut microbiome can help us be less susceptible to viral infections (Altman et al 2020)—maybe even COVID 19.
Vitamin D has a collaborator in the gut to dampen proinflammatory responses and alter cytokine production. Butyrate is produced in the gut from the microbial fermentation of carbohydrates, particularly resistant starch and dietary fiber such as inulin. It supplies all the energy to the cells that regenerate the surface of the colon (colonocytes). Vitamin D and the gut microbiota work together to reduce gut inflammation and uphold the integrity of the first defense force (Liu et al 2018; Dimitrov and White 2017). It has been suggested that vitamin D supplements might be an easy and inexpensive way to positively modify the gut microbiota.
There are specific communities of microbes — associated with our sinuses and upper respiratory tract — called the nasopharyngeal microbiome, that if maintained can reduce the risk of viral infections. Studies have suggested that there are specific bacteria that protect the airways from viruses and reduce the risk of getting a viral infection (Altman et al 2020). We need more research to understand how these microbiomes strengthen our barrier defense forces.
Vitamin D has known direct effects on respiratory infections (Chang and Lee 2019; Daley et al 2019; Rondanelli et al 2018) mediated through the innate immune system, or the second defense force. Specialized cells work together with vitamin D to produce anti-bacterial proteins that kill invaders, as well as cells that then dampen the inflammatory response to the dead cells, allowing for a faster recovery (McCullough and Lehrer 2019). By mobilizing the innate antimicrobial defense force, vitamin D plays a critical role in eliminating invading bacteria, viruses, and fungi (Chirumbolo et al 2017; Wu et al. 2019). Clearly, with adequate sun and nutrition we do have a fighting chance against viral respiratory diseases.
Always On Guard
The specialized forces of the third or adaptive immune system patrol the body for known pathogens and invaders, including any signs of potential cancer-causing (malignant) cells. Allergies are generally a result of the inflammation caused by the third defense force. Vaccinations stimulate an adaptive immune response so the third defense force will instantly recognise the invader and mount a swift attack. Vitamin D activates anti-inflammatory, anti-oxidant and anti-fibrotic actions (Dankers et al 2017; Wessels and Rink 2020) within the adaptive immune system, reducing the inflammation, pain, and tissue damage caused by aggressive third defense force attacks. Having sufficient vitamin D is protective against developing a number of autoimmune diseases, and can reduce the tissue damage from thyroid disease (Murdaca et al 2019). Nutritional strategies are strongly advised as part of an integrated approach to decrease the incidence of autoimmune diseases (Malaguarnera, 2020; Wessels and Rink 2020) which are a consequence of the adaptive immune system attack forces.
Vitamin D is a simple and cost-effective health solution
With our modern lifestyle we also entered the era of antibiotic-resistant diseases, and skyrocketing healthcare costs. Let’s use the COVID-19 pandemic to reboot, and set a goal to develop simple and cost-effective approaches that integrate nutritional outcomes with disease management strategies. Studies examining the interactions between chronic disease and vitamin D have shown over and over again that individuals with sufficient vitamin D have better health outcomes, and generally stay well. The lowest effective dose of vitamin D needed to maintain health, or in therapeutic use against disease, is still debated (McCullough and Lehrer, 2020). Most agencies have agreed that the daily supplement dose of vitamin D in the winter must be higher than 400 IU for children and 800 IU for adults to maintain health.
The scientific research consistently demonstrates that there is enough evidence from clinical and research trials to adequately determine safe vitamin D dosing levels. Intake of more than 50,000 IU can cause clinical signs of vitamin D toxicity, while experiments using prolonged doses of 40,000 IU reported no adverse health effects (Brower-Brosma et al 2013). However, it is generally recommended that routine prolonged adult doses of as much as 10,000 IU are safe to maintain health and the immune defense forces in winter months (Holick, 2007; McCullough and Lehrer 2019). Vitamin D supplements, cod liver oil, sunshine and phototherapy are proven and forgotten low tech, inexpensive treatments that have the potential to safely end global vitamin D deficiency and many of the associated diseases. The body needs optimum levels of micronutrients including vitamin D to support all three of the immune defense forces and keep them in fighting condition. The scientific and clinical evidence exists to support supplementing diet with combinations of multiple, specific, and immune system supportive micronutrients to optimize immune function and reduce the risk of infection (Gombart et al 2020).
There is no hard evidence that vitamin D has any effect on COVID-19, but there is a lot of evidence to show that people with sufficient levels of vitamin D have better overall health, and if they do get sick, they have less severe symptoms, and recover more quickly.
It is clear to me that micronutrients including vitamin D are fundamental to the fitness regime of our immune system defense forces. As I said at the beginning, I believe that all things are ultimately connected—even if we don’t know it yet. To me, the interaction between vitamin D, gut microflora, fiber intake, and our health reinforces the need to look at systems as a whole. Feeding yourself whole grains and fermented foods for the gut microbes, fruits and vegetables for the minerals, vitamins and enzymes, and adding some physical exercise in the sun can clearly help your immune system to fight a pandemic.
Jill Clapperton is Principal Scientist and Founder of Rhizoterra Inc. as well as being Chief Scientist to the Real Food Campaign. She is not a medical practitioner and the opinions and views expressed in this article are her own based on the research she has done. This series is co-sponsored by Rhizoterra Inc and the Bionutrient Food Association. The Real Food Campaign and Our Grounded Growth help us to get the message out. I thank Dr’s David Pearce, James Frame, and Curt Livesay for reviewing this paper.
We have omitted notes from this article for space reasons. Anyone wishing the original version of this article can get one by Emailing the editor for a copy. I will send it to you as a .docx attachment.
– Jack (TNF (at) nofa.org)