Vitamin D plays an overlooked role in the immune defense. Being deficient of the nutrient increases your risk of bacterial pneumonia by up to 60 percent, according to a large Danish study of 116,000 participants that was carried out by scientists from Herlev Hospital, Gentofte Hospital, and the University of Copenhagen.
Because many older people, cancer patients, and other chronically ill individuals are at increased risk of respiratory infections and because bacterial pneumonia can be potentially lethal, the scientists see a huge potential in using vitamin D supplements to prevent the disease.
Pneumonia is a common term for a variety of lung tissue infections. The disease often trails typical viral infections such as colds and influenza that circulate during the winter period. If a person has a weak immune defense, bacteria from the natural microflora in the nose and throat may enter the lungs where they replicate and cause infection. Most cases of pneumonia are caused by a type of streptococcal bacteria called pneumococcus. In Denmark, around 15,000 people are hospitalized with pneumonia every year. Others receive treatment from their GP.
Every year, around 1,600 people die of pneumonia. On a global scale, infections in the lower respiratory tract, pneumonia included, cause more deaths than cancer, coronary thrombosis, HIV, and malaria combined. Approximately 90 percent of deaths occur among people aged 65 and older. There is a lot to suggest that lack of vitamin D, a problem that is very common during the winter period and also among older people and chronically ill, increases both the risk of the infection and the risk of it becoming life-threatening.
The lower the vitamin D levels, the higher the risk
The scientific study from Herlev Hospital, Gentofte Hospital, and the University of Copenhagen is based on a Danish study called “Østerbro-undersøgelsen” (the Østerbro study) where scientists measured genetic variants of vitamin D in blood samples from 116,000 people. This helps to determine levels of vitamin D in the body. The same goes for exposure to sun during the summer period. Sun exposure is the main source of vitamin D at our latitudes because there is very little vitamin D in the diet. Older people, dark-skinned people, diabetics, cancer patients, and people with chronic diseases have difficult with synthesizing and utilizing the nutrient and are more likely to become deficient. The new Danish study revealed that lack of vitamin D affects the immune system’s ability to fight bacteria in the airways and lungs. The scientists could see that the risk of bacterial pneumonia increased by 12-63 percent for every 10 nmol/L drop in blood levels of vitamin D. The more vitamin D-deficient a person is, the greater the risk of contracting bacterial pneumonia.
The researchers also looked at vitamin D levels and the participants’ risk of urinary tract infections, skin infections, blood poisoning, and gastrointestinal infections but were unable to find a similar causal link.
The new Danish study is published in British Medical Journal.
The next step for the researchers is to conduct a randomized study to investigate if vitamin D supplements are able to prevent bacterial pneumonia.
For the record, blood levels are categorized as “deficiency” (below 30 nmol/L), “insufficiency” (30-50 nmol/L), and “sufficiency” (over 50 nmol/L). Many international experts believe the optimal level is somewhere in the range of 60-100 nmol/L.
An earlier meta-analysis (Martineau et al.) that was also published in British Medical Journal has already reported that vitamin D supplements are able to lower the number of acute respiratory infections, including bacterial pneumonia, by up to 42 percent. The greatest effect was seen among the participants who were most vitamin D-deficient to begin with and who got larger doses.
Why does vitamin D protect against respiratory infections?
Vitamin D has a vital but overlooked role in both the innate immune system and the adaptive immune system, which is our ancient defense against millions of different microorganisms. Vitamin D is of particular importance for the respiratory tract where is produces antibiotic peptides that are used for fast elimination of microorganisms.
Moreover, vitamin D helps a special type of white blood cells called T cells so that they can replicate quickly and carry out frontal attacks against bacteria and virus. But if the T cells are not able to absorb enough vitamin D from the blood, they lose their ability to collaborate, to attack, or to develop immunity. Vitamin D also helps the immune defense carry out its targeted attacks without overreacting. This is a vital feature because it is the sudden and very violent immune reactions that can cause hyperinflammation and damage healthy tissue in the lungs and other places.
How much vitamin D do we need?
In Denmark, the reference intake (RI) level for white adults up to the age of 70 years is five micrograms per day. The Danish Health Authority recommends a 10-microgram daily supplement for pregnant women, toddlers, people with dark skin, and individuals who do not spend enough time in the sun. Nursing home residents and people from 70 years and older are advised to take 20 micrograms. Unfortunately, there are no systematic control measures to make sure that people comply with these recommendations.
Besides, many scientists claim that the actual need for vitamin D is way above the RI level, and our need for the nutrient depends on a number of factors such as genetics, sun exposure, age, skin type, BMI, use of cholesterol-lowering drugs, plus chronic disease like cancer and diabetes. High-dosed supplements with 20-80 micrograms of vitamin D are available on the market.
EU´s Scientific Committee on Food has set 25 micrograms per day as the safe upper intake level for vitamin D for infants aged 0-6 months. The level is 50 micrograms for children aged 6 months to 10 years, and 100 micrograms is the level for children older than 11 years and adults, including pregnant and breastfeeding women.
Vitamin D is a lipid-soluble nutrient. Therefore, we are best able to absorb and utilize it if we ingest the vitamin in oil in soft gelatin capsules.
Yunus Colak, Børge G Nordestgaard, Shoaib Afzal. Low vitamin D and risk of bacterial pneumonias: Mendelian randomisation studies in two population-based cohorts. BMJ 2020 Oct 27
Gentofte Hospital. Lavt D-vitamin øger risikoen for bakteriel lungebetændelse.
Adrian R Martineau et al. Vitamin D supplementation to prevent acute respiratory tract infections. Systematic review and meta-analysis of individual participant data. BMJ 2017
University of Copenhagen. Vitamin D crucial to activating immune Defences. 2010
University of Colorado Anschultz Medical Campus. Vitamin D reduces respiratory infections. ScienceDaily November 2016
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