Share on PinterestWhy does vitamin D supplementation not work as well for everybody? Image credit: Xvision/Getty Images.
People with obesity are more likely to have a vitamin D deficiency.
Trials designed to determine whether or not vitamin D supplementation has a beneficial effect have repeatedly reported inconclusive results.
Secondary analysis of one of the largest trials to date — the VITAL study — into the effect of vitamin D supplementation showed different levels of beneficial effects for people with different body mass indexes (BMIs).
The study team has now shown that vitamin D supplementation is less effective at correcting deficiencies in people with obesity than in people with a BMI below 25.
This deficiency has also been linked to cancer risk and poorer cancer treatment outcomes. Obesity is also a risk factor for many of these conditions.
Increasingly, research has shown that supplementation with vitamin D in people with obesity, defined as having a BMI over 30, does not correct the deficiency as effectively as it does in people with a BMI under 25.
Dr. Linia Patel, consultant dietitian, sports nutritionist, and British Dietetic Association spokesperson, told Medical News Today in an interview that her own research on a cohort of 2,842 individuals under 40 in the United Kingdom showed that vitamin D deficiency was associated with higher BMI and waist circumference.
BMI is a measurement that infers overall adiposity, or body fat, and the waist measurement infers the amount of visceral fat an individual may have in their abdomen.
“We’ve got two issues going on,” said Dr. Patel. “We have seen that […] people […] who are obese have lower vitamin D, starting off. And then even when you supplement them, their levels of vitamin D don’t go as high as people having ‘normal weight.’ So that’s one issue.”
“If you are having a higher BMI, you are more at risk of cardiometabolic risk factors, and what’s fantastic for me, as a public health dietitian, is [that] if we supplement people with vitamin D, we reduce that risk,” she told us.
The issue was that vitamin D supplementation advice is “one size fits all,” with little consideration given to different populations, she said.
The potential role vitamin D deficiency can play in increasing the risk of developing different conditions is controversial, with many trials and studies reporting inconclusive results.
It is also possible that the trials were asking the wrong questions in the first place, said Dr. Patel.
“A lot of other research that has been done into vitamin D hasn’t looked specifically at the right question. So you can see that the research is conflicting in this area. And a lot of research actually shows that vitamin D supplementation doesn’t make a difference, but some shows then that vitamin D supplementation does make a difference in reducing your risk factors.”
– Dr. Linia Patel
“And I think the papers that showed that it doesn’t make a difference, are perhaps not using a high enough dose, and perhaps not asking the right questions in terms of what, in fact, are we looking at? Are we looking at when people die? Are we looking at their risk of diseases? So I think we just need more specific and good quality research in this area,” she added.
The VITAL study sought to determine the effects of vitamin D and omega-3 supplementation on cancer and cardiovascular events in a cohort of 25,871 adults in the United States.
The initial results from the trial were published in the New England Journal of Medicine in 2019 and showed that while vitamin D supplementation did not reduce the risk of cancer, cardiovascular disease, or bone fractures in the cohort, the risk of cancer-related death was reduced with supplementation.
This effect did not occur in people with overweight or obesity, which led the researchers to carry out a further analysis to quantify the difference in the impact of vitamin D supplementation on people with different BMIs. The results of this research appear in JAMA.
Researchers looked at the vitamin D levels of 16,515 participants before and after supplementation, as well as their BMI.
This paper shows that those with a BMI below 25 were less likely to have a vitamin D deficiency in the first place, and more likely to see their vitamin D deficiency corrected with vitamin D supplementation than those with a BMI over 30.
The authors proposed that this difference could be due to the difference in the activity of the parathyroid hormone, which can stimulate vitamin D production in the kidneys when a person has low levels, in people with a higher BMI.
In people with a BMI under 25 researchers expect that there is an inverse relationship between vitamin D levels and parathyroid hormone levels, but the level at which vitamin D supplementation can lower parathyroid hormone levels is likely to be higher in people in obesity than in people without.
Prof. JoAnn Mason, professor of medicine at Harvard Medical School, and principal investigator of the VITAL trial told MNT that “[t]he parathyroid hormone didn’t come down, […] it didn’t reduce as much in response to supplementation in those with higher BMI.”
Next, the team wants to investigate whether or not the dosage of vitamin D makes any difference to people at different BMIs as well as looking at the gene expression that occurs in people when they are given vitamin D supplementation.
Prof. Mason added: “We really believe that more attention [should] be given to body mass index, and to adiposity as a factor in modifying the effects or possibly blunting the effects of vitamin D supplementation. Because if you don’t take that into account, you can actually misinterpret the vitamin D trial.”
Share on PinterestConsuming vitamin D may be beneficial to health but this may not translate to a protective effect against disease. Spencer Platt/Getty Images
Vitamin D has many health benefits such as building strong bones and boosting a person’s immune system.
Two new studies report that vitamin D supplements do not offer protection against acute respiratory infections or a SARS-COV-2 infection.
Despite disappointing results, researchers plan to continue to follow study participants to see if there are any additional health outcomes from vitamin D supplementation.
Vitamin D is most known for its role in promoting strong bones by ensuring the body absorbs calcium properly. However, researchers also believe vitamin D helps boost a person’s immunity and may provide protection against developing diseases like diabetes and asthma.
Additionally, past research has shown that vitamin D may help protect the body from respiratory tract infections. There has also been research conducted on a link between vitamin D deficiency and a greater chance of developing COVID-19.
Now, two new clinical studies recently published in the journal TheBMJ report that vitamin D supplements do not help reduce acute respiratory infections or infection by SARS-CoV-2, the virus that causes COVID-19.
The first clinical study took place in the United Kingdom and was conducted by a research team from the Queen Mary University of London. Researchers enrolled 6,200 people ages 16 and over who were not currently taking vitamin D supplements.
Following a blood analysis of their vitamin D levels, researchers administered either a low or high dose of vitamin D to the study participants. After a six-month follow-up, scientists found at least one acute respiratory tract infection of any cause occurred in 5.7{cfdf3f5372635aeb15fd3e2aecc7cb5d7150695e02bd72e0a44f1581164ad809} of the low-dose vitamin D supplement group and 5{cfdf3f5372635aeb15fd3e2aecc7cb5d7150695e02bd72e0a44f1581164ad809} in the higher-dose group.
Additionally, 3.6{cfdf3f5372635aeb15fd3e2aecc7cb5d7150695e02bd72e0a44f1581164ad809} of participants in the low-dose vitamin D group and 3{cfdf3f5372635aeb15fd3e2aecc7cb5d7150695e02bd72e0a44f1581164ad809} in the higher-dose group developed COVID-19, compared to 2.6{cfdf3f5372635aeb15fd3e2aecc7cb5d7150695e02bd72e0a44f1581164ad809} of participants not offered a vitamin D supplement.
The second study was conducted by a research team from Oslo University Hospital in Norway.
“We were trying to prove that vitamin D actually could prevent COVID-19 and other respiratory tract infections,” principal investigator Dr. Arne Søraas in the Department of Microbiology at Oslo University Hospital explained to Medical News Today.
“There has been a lot of research into vitamin D as a ‘booster’ for the immune system and even meta-analyses that have shown it to be effective in preventing such infections. There was, therefore, a hope that it could also prevent COVID-19 which is also an airway infection.” — Dr. Arne Søraas
This study focused on the use of a cod liver oil supplement to prevent acute respiratory infections and COVID-19. Cod liver oil contains high amounts of vitamin D, vitamin A, and omega-3 fatty acids.
Dr. Søraas said he also led the Norwegian Corona Cohort study where scientists followed 200,000 Norwegians through the pandemic.
“There we observed that cod liver oil users were less likely to catch COVID-19,” he said. “Cod liver oil is a widely used supplement in Norway.”
Dr. Søraas and his team administered cod liver oil or a placebo to about 34,600 adults not currently taking vitamin D supplements. After taking the cod liver oil or placebo for a median of 164 days, 1.31{cfdf3f5372635aeb15fd3e2aecc7cb5d7150695e02bd72e0a44f1581164ad809} of cod liver oil takers had developed COVID-19, compared to 1.32{cfdf3f5372635aeb15fd3e2aecc7cb5d7150695e02bd72e0a44f1581164ad809} of placebo takers. The cod liver oil group also had a higher percentage of those developing serious COVID-19 — 0.70{cfdf3f5372635aeb15fd3e2aecc7cb5d7150695e02bd72e0a44f1581164ad809} compared to 0.58{cfdf3f5372635aeb15fd3e2aecc7cb5d7150695e02bd72e0a44f1581164ad809} in the placebo group.
Additionally, the research team did not observe a reduction in the incidence of acute respiratory tract infections in those taking cod liver oil compared to those taking the placebo.
Dr. Søraas said the findings surprised him and his research team. “We would not have set up such a large project if we did not truly believe that we would find that vitamin D could prevent COVID-19,” he added.
“We will now follow all the participants for at least two years and study self-reported health outcomes, as well as health outcomes from national Norwegian registries, to identify any longer-term health effects of our intervention,” Dr. Søraas continued.
“Cod liver oil did increase vitamin D and omega-3 levels in the study — unsurprising, of course — and the study is a great opportunity to study rare side effects, as well other possible effects. All the 35,000 cod liver oil participants are also a part of the Norwegian Corona Cohort where we have a lot of the focus on long-COVID,” he added.
MNT also spoke with Dr. Jimmy Johannes, a pulmonologist and critical care medicine specialist at MemorialCare Long Beach Medical Center in Long Beach, CA, about these two studies. He said he was not particularly surprised by the results of these studies.
“Prior studies evaluating vitamin D supplementation on the prevention of acute infections had mixed results. [I] think if there’s any effect, it would be small,” he said.
When asked about the next steps he would like to see for this research, Dr. Johannes said: “If you’re really looking for an effect, you might need a larger study that’s better controlled to find any effect.”
“Having said that, [if] we think there’s an effect [and] it would be small, [it] therefore [raises] the question, would this effect be clinically important? And should we spend the expense of doing this kind of clinical trial that would be very expensive to do a well-controlled, large clinical trial to find this kind of effect?” he concluded.
Share on PinterestStudies on vitamin D health supplements for preventing diabetes have proven inconsistent benefits so much. CHAIDEER MAHYUDDIN/AFP by means of Getty Illustrations or photos
Vitamin D deficiency has been connected to an improve in risk for a number of problems, such as sort 2 diabetic issues.
Quite a few studies have sought to determine whether or not, how significantly, and which type of vitamin D nutritional supplements could support to decrease the threat of producing type 2 diabetic issues.
The hottest study shows that these studies have mainly proved inconclusive and the reduction in hazard that could be furnished by every day vitamin D supplements is compact.
Vitamin D deficiency is a developing issue, especially in international locations in the northern hemisphere. Similarly, so is variety 2 diabetes. This has led some researchers to think there could possibly be a link amongst the two.
The proposed system powering this theory is that vitamin D is essential for insulin secretion to be at a nutritious level, so a absence of it could not only put persons at threat of type 2 diabetes but also make insulin resistance even worse in people who do have style 2 diabetic issues.
Having said that, researchers have identified it complicated to confirm that supplementation with vitamin D could lower the hazard of kind 2 diabetes, even in these who have been diagnosed as pre-diabetic.
A meta-investigation revealed in Diabetic issues Care in 2020 discovered a tiny reduction in risk of all over 11{cfdf3f5372635aeb15fd3e2aecc7cb5d7150695e02bd72e0a44f1581164ad809} from vitamin D supplementation in men and women with prediabetes following some significant profile studies failed to present a important outcome.
The hottest examine, carried out in Japan and published in the BMJ, has also identified no considerable effect.
In this multi-middle, double-blind randomized placebo command demo involving 1,256 contributors, researchers sought to evaluate the outcomes of each day vitamin D on diabetes danger.
They appeared at whether or not 630 individuals classed as pre-diabetic had been significantly less very likely to acquire kind 2 diabetes when offered .75μg of eldecalcitol—an energetic vitamin D analogue—daily, when as opposed to a group of 626 members given a placebo.
They followed up on the contributors for an ordinary of 2.9 years, evaluating their fasting plasma glucose measurements at the begin of the trial and each individual three months, as very well as measurements from glucose tolerance assessments carried out at the start out and then yearly. The scientists also seemed at the participants’ bone density measurements per year.
Dr. Tetsuya Kawahara, guide creator of the review from the College of Occupational and Environmental Wellbeing, Kitakyushu, Japan advised Health care News Now that their effects ended up combined.
The group provided eldecalcitol confirmed a decrease of 13{cfdf3f5372635aeb15fd3e2aecc7cb5d7150695e02bd72e0a44f1581164ad809} in their threat of producing form 2 diabetic issues about the research time period but the scientists discovered it was not considerable.
“Despite the reality that eldecalcitol (an lively vitamin D analogue) has been proven to protect against kind 2 diabetes advancement in our pilot review, treatment method with it did not present a preventive influence on the incidence of form 2 diabetic issues, nor a effective result on the level of regression to normoglycaemia in this present examine,” he explained.
Nevertheless, they found that a certain group seemed to get superior results.
“[A]fter altering for 11 probably influential factors, together with age, sexual intercourse, blood stress, body mass index, and household background of diabetes, the effects suggested that eldecalcitol may well protect against form 2 diabetes in prediabetic clients with inadequate insulin secretion,” Dr. Kawahara said.
He claimed he thinks the explanation at the rear of these mixed final results could be that the review was underpowered.
Dr. James Brown from Aston Analysis Centre for Nutritious Ageing at Aston University in Birmingham, United Kingdom, who studies type 2 diabetic issues and metabolism, highlighted the very same issue.
“The examine protocol which was released in 2016, and involved a sample dimensions calculation for the major result of diabetes diagnosis which was 750 members, dependent on an believed 36{cfdf3f5372635aeb15fd3e2aecc7cb5d7150695e02bd72e0a44f1581164ad809} decreased danger, while in the closing facts the danger was claimed as 13{cfdf3f5372635aeb15fd3e2aecc7cb5d7150695e02bd72e0a44f1581164ad809},” he mentioned.
“It is achievable that the review was underpowered to detect the principal final result. It is not crystal clear from the review protocol if the secondary results are sufficiently powered,” he instructed MNT.
Dr. Tatiana Christides, from the Queen Mary College of London who wrote an accompanying editorial for the analyze in the BMJ, reported that even a compact change in possibility for building sort 2 diabetes could be essential on a inhabitants amount as so a lot of folks have prediabetes.
“Depending on which literature you read, there is a risk of 5-10{cfdf3f5372635aeb15fd3e2aecc7cb5d7150695e02bd72e0a44f1581164ad809} of progression among men and women with prediabetes,” she advised MNT in an job interview.
She went on to explain with an case in point:
“Let’s say there are 100 people today with prediabetes, and each calendar year 10 of them are likely to go on to create complete-blown diabetic issues. That implies you’d be stopping 1 of individuals 10 persons from heading on to get full-blown diabetes. Which is, at a public wellness amount, [s]ignificant,” she stated.
Even so, Dr. Christides also stated she had problems that advising men and women to get vitamin D to avert building kind 2 diabetes. Without the need of sturdy evidence, this may well prevent people from seeking interventions to lessen possibility, these types of as bodyweight loss, which there is considerably more powerful evidence for, she added.
Share on PinterestA new research provides to the evidence that COVID-19 severity may possibly have ties to vitamin D deficiency. Lam Luong Dinh/EyeEm/Getty Photographs
Some exploration implies vitamin D insufficiency has ties to worse COVID-19 results.
A new review that considers pre-infection vitamin D stages confirms their url to significant COVID-19.
The scientists say their conclusions do not essentially indicate that vitamin D therapy will impact COVID-19 results, though they recommend keeping regular stages is smart.
Having sufficient concentrations of Vitamin D is important for selling nutritious bones and tooth. Also tiny of it has links to diabetic issues, autoimmune, cardiovascular, and infectious disorders. Among the these is COVID-19.
Scientists at Bar Ilan College and the Galilee Medical Heart in Israel have produced a research that examines the hyperlinks involving Vitamin D degrees and the severity of COVID-19 for 253 individuals admitted to the clinic. with COVID-19 The researchers found records indicating their vitamin D concentrations in advance of they obtained a SARS-CoV-2 infection and went to the healthcare facility.
The examine concluded that individuals with insufficient pre-an infection degrees of vitamin D have been 14 periods additional possible to build extreme COVID-19 than all those with significant vitamin D amounts.
The study’s guide author is Dr. Amiel Dror, a Galilee Healthcare Middle and Bar Ilan researcher. He advised Medical Information These days why he suspects prior study investigating the connection concerning vitamin D insufficiency and COVID-19 has been inconclusive and even contradictory:
“The vast majority of the reports (at the very least at the early pandemic phase) have tackled vitamin D in the context of acute viral an infection. These scientific studies aimed to evaluate no matter if minimal vitamin D in the presentation to the hospital is involved with COVID-19 disease final result. Vitamin D measurement [during] a patient’s COVID-19 ailment represents the vitamin D level at a unique time position.”
Dr. Dror said that when a single measures the vitamin D degrees of a particular person who already has SARS-CoV-2 an infection, it is complicated to know if COVID-19 is suppressing vitamin D or if the deficiency of it aggravates the infection.
Dr. Dror defined that “vitamin D undergoes activation in the liver to develop into active. A lot of COVID-19 individuals suffer from an impaired liver functionality that abolishes the capacity to activate vitamin D in the course of the illness.”
Dr. Iacopo Chiodini, affiliate professor of endocrinology at Università degli Studi di Milano, Italy, instructed MNT that scientists have not nonetheless founded how vitamin D might support have COVID-19 even if there is sufficient of it. Dr. Chiodini was not associated in the examine.
Dr. Chiodini instructed vitamin D may perhaps act, for instance, as a modulator of the cytokine storm that sales opportunities to lung injury and illness development or of neutrophil action, “thus reducing their extreme activation and recruitment into the infected lung.”
He also speculated that vitamin D may well guard the integrity of and mend the pulmonary epithelial barrier or reduce the danger of lung and systemic thrombosis found in serious COVID-19.
Over and above that, claimed Dr. Chiodini:
“Vitamin D deficiency can be one particular indicator of a wide selection of serious wellness circumstances or behavioral variables that simultaneously maximize COVID-19 disorder severity and mortality dangers.”
A next place exactly where previous investigation has demonstrated inconclusive entails no matter if vitamin D supplementation for the duration of illness with COVID-19 has benefit. Dr. Dror cited one examine in which individuals been given supplemental vitamin D roughly 10 days just after the onset of COVID-19 signs and symptoms:
“Obviously, it must be no shock that these a late intervention would not change the observed disease training course that much. When a review aims to establish the outcome of vitamin D cure, [I] would endorse a study style and design with earlier intervention/remedy relatively than 5-10 times right after the symptoms’ onset when the physique has now been through serious distress.”
In the new research, the dilemma remains unanswered. As Dr. Chiodini reminded MNT, “an association concerning pre-infection vitamin D deficiency and COVID-19 severity does not necessarily suggest that vitamin D treatment method will affect COVID-19 results.”
Right after accounting for a assortment of other feasible aspects, stated Dr. Dror, “Vitamin D impact was so potent, and identified in each individual multivariate regression model we tested as the most popular impartial element on disorder severity and mortality.”
Dr. Dror mentioned that his research is observational and included: that “I absolutely agree that randomized controlled trials are crucial to displaying causation” in between vitamin D and COVID-19 results.
He continued: “Having said that, there are lots of fantastic reasons for preserving normal vitamin D stages (bone and skeletal well being, and so forth.) regardless of COVID-19. Consequently, If it could be beneficial to battling the respiratory viral infection, I cannot see a rationale to steer clear of it.”
“Altogether, I endorse that people hold their baseline vitamin D at a usual amount and unquestionably keep away from the deficiency degree of 20 nanograms for every milliliter (ng/ml). These tips presently exist irrespective of the COVID-19 pandemic. In the course of this interval, I would specifically stick to these recommendations.”
– Dr. Dror
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Share on PinterestA new study searches for links between vitamin D supplements, cancer, and heart disease. Raymond Forbes LLC/Stocksy
Initial research has suggested that vitamin D may reduce the risk of developing cardiovascular disease and cancer.
However, there have been few large, higher-quality randomized controlled trials (RCTs) to corroborate this.
A recent RCT examined the effects of vitamin D supplementation in Finland.
It found no association between vitamin D supplementation and reduced risk of cardiovascular disease or cancer.
Vitamin D helps the body absorb calcium, which improves bone strength. Among other roles, it also contributes to the functioning of muscles, nerves, and the immune system.
Many scientists have set out to understand how vitamin D deficiency and supplementation may influence disease. According to the World Health Organization (WHO), there is some evidence that vitamin D may help protect against respiratory tract infections, for example.
Over the past 2 years, researchers have also explored whether vitamin D reduces the risks associated with COVID-19. Although investigations are ongoing, there seems to be some evidence that these supplements might improve intensive care unit admission rates.
Two other areas of particular interest are vitamin D’s potential effects on cardiovascular disease and cancer risk. However, few RCTs have looked into this. These types of studies are the gold standard for identifying causal relationships in scientific research.
Speaking with Medical News Today, Vimal Karani, a professor of nutrigenetics and nutrigenomics at the University of Reading, in the United Kingdom, confirmed that there has been a gap between the initial research and findings from clinical trials.
Prof. Karani was not involved in the recent study but has worked with some of its authors.
He explained that past large epidemiological studies “have established a link between vitamin D deficiency and the risk of [cardiovascular disease] traits in various ethnic groups.” This, he said, suggests that vitamin D supplements might lower cardiovascular risk.
“However,” he continued, “clinical trials have not provided convincing evidence of the blood pressure-lowering effect of vitamin D supplementation.”
Prof. Karani said that there could be a wide range of reasons for this, including “differences in the sample size, duration of supplementation, dose of the supplementation, age of the participants, geographical location, sun exposure, and the outcome measures. Further research is required to replicate the findings in multiple ethnic groups.”
To provide further evidence of the relationship between vitamin D, cardiovascular disease, and cancer, the researchers behind the present study conducted the Finnish Vitamin D Trial.
This took place between 2012 and 2018, and it was double-blind, randomized, and placebo-controlled.
“When we started to plan the trial, there was a lot of evidence from observational studies that vitamin D deficiency would be associated with nearly all major chronic diseases, such as [cardiovascular disease], cancer, type 2 diabetes, and also mortality,” said Dr. Jyrki Virtanen in an interview with Medical News Today.
Dr. Virtanen is an associate professor of nutrition and public health at the University of Eastern Finland, and a co-principal investigator of the study.
“Also, we had shown that among [the] Eastern Finnish population, low vitamin D content of the body was associated with higher risk of mortality and glucose metabolism disturbances. However, these kinds of studies do not give evidence for causality.”
“At that time, there was little evidence from RCTs that improvement of [the] vitamin D status of the body with vitamin D supplementation reduced the risk of diseases.”
“Therefore, our aim was to start a long-term vitamin D supplementation trial in Finland, where vitamin D insufficiency had been quite prevalent due to the long winter, and investigate whether vitamin D supplementation could reduce the risk of major chronic diseases and death.”
The researchers looked at data from 2,495 people, including male participants 60 years or older and female participants who were postmenopausal and 65 years or older. The participants also had no history of cardiovascular disease or cancer.
The participants either took a placebo, vitamin D at a dosage of 1,600 international units (IU) each day, or vitamin D at a dosage of 3,200 IU each day.
Compared with the placebo, neither dosage of vitamin D reduced the incidence of cardiovascular disease or cancer in this cohort, the team determined.
One factor that complicated this analysis was that the participants tended to have high levels of vitamin D at the start of the study. This, the authors believe, stems from the implementation of policies to fortify foods with vitamin D in Finland, which began in 2003–2011.
“It is likely that vitamin D supplementation does not provide major health benefits, especially in populations where the vitamin D situation is already good at the start of the trial.”
– Dr. Jyrki Virtanen
“A ‘problem’ with most large vitamin D supplementation trials has been that the starting levels of vitamin D have been pretty high in a large part of the study populations,” explained Dr. Virtanen.
“This may reflect the well-known fact that people who take part in these kinds of studies tend to be more health-conscious and more interested in their health, so they are, on average, healthier than the average population.”
“They may have a better diet and are more likely to take supplements and exercise, which all are associated also with higher serum vitamin D levels,” he told MNT.
“Those who might benefit from the vitamin D supplementation — i.e., those with low serum vitamin D levels — are a small minority in the trials. It is tricky to target this deficient population, though, because for ethical reasons it would not be possible to screen people and only admit people with low vitamin D levels in the trial. It would not be ethical to keep a part of the study population, the placebo group, deficient [in] vitamin D for several years.”
They explained that despite the low recruitment levels — the study authors had hoped to recruit 30,000 participants — the results showed some signs that vitamin D had health benefits.
“Even though recruitment was challenging and didn’t meet expectations, there is some indication that the cohort investigated had lower incidence of both [cardiovascular disease] and cancer, compared to national statistics, which would have been gathered prefortification.”
“This may indicate that improvements to vitamin D status nationally are having benefits to the overall health of the population over and above the well-known bone and muscle health effects. Because of the low numbers recruited, the cohort may not be nationally representative, and care should be taken when interpreting these findings,” said the scientists.
According to Prof. Karani: “The unique feature of this RCT was the use of two different vitamin D doses to see the dose-response effect over a period of 5 years. Despite the large doses, the study failed to see any effect of the supplementation on lowering the incidence of [cardiovascular disease] and cancer.”
“The findings have significant public health implications,” continued Prof. Karani. “However, the findings cannot be generalized to other populations, given that [the] Finnish population is a well-known example of an isolated population, where multiple bottlenecks resulting from consecutive founder effects have led to the gene pool of current-day Finns.”
Dr. Virtanen said that while there is some evidence of broader health benefits from vitamin D supplementation, there were also conflicting findings.
“At the moment, there is no consensus [about] what would be the optimal vitamin D intake and [whether it is] the same for all health outcomes and for all people. For example, there is some evidence that high-dose vitamin D supplementation may modestly reduce the risk of cancer death, but not overall cancer incidence.”
“And although there, so far, is no evidence that vitamin D supplementation could prevent [SARS-CoV-2] infection, it is well-documented that those, especially with the severe form of COVID-19, have low serum vitamin D levels.”
“It is also possible that this is a consequence of the [SARS-CoV-2] infection rather than the cause, because it is known that acute infection leads to lower serum vitamin D levels, and many of the COVID-19 patients are overweight or obese or have a chronic disease like type 2 diabetes, which all are associated with lower serum vitamin D levels,” explained Dr. Virtanen.
Prof. Strain, Dr. McSorley, and Dr. Magee highlighted the role that vitamin D may play in a healthy immune system.
“There is recent strong evidence that vitamin D supports your immune system, and given the global pandemic, it does appear that those who are vitamin D replete don’t have as severe a response to COVID-19 as those who are deficient — and importantly, recover quicker.”
“Vitamin D plays a key role in musculoskeletal health. Vitamin D can be obtained via sunlight and dietary sources. However, a vitamin D supplement may be required to meet the recommended dietary intakes — that is, 600 IU per day in the United States for those aged 1–70 years, and 800 IU per day for those over 70 years — in order to maintain a sufficient status.”
“Supplementation may be particularly relevant in populations residing at northerly latitudes, where vitamin D cannot be synthesized from sunlight during the winter months, and in populations that spend little time outdoors and/or obtain limited amounts of vitamin D from food sources.”
“It is very difficult to obtain vitamin D from food intake alone, unless that food is fortified with vitamin D. Furthermore, those with illnesses that affect vitamin D absorption may require vitamin D supplementation,” said the scientists.
Prof. Strain, Dr. McSorley, and Dr. Magee suggested that the research could be developed by studying a population with low levels of vitamin D.
“This research needs to be undertaken in a suitable population, where many have a low vitamin D status and can therefore benefit from vitamin D supplementation.”
“It would be important to explore whether vitamin D supplementation can decrease the incidence of [cardiovascular disease] and cancers, as that would make a strong case for mandatory vitamin D fortification or promotion of fortified foods in the population.”
“There is some tantalizing evidence that the Finnish national [vitamin D] fortification program is having benefits by decreasing the incidence of [cardiovascular disease] and cancers, as well as the expected beneficial effects on bone health.”
“Another very important area that needs to be explored further is the link between sufficient vitamin D status and a fully functional immune system, especially in light of the current COVID-19 pandemic.”
As Prof. Karani notes, “A similar RCT with a longer duration of vitamin D supplementation is highly warranted in ethnically diverse populations to see if the findings from the present study could be generalized.”
Dr. Virtanen told MNT that his current focus is on further analyzing the results from the Finnish Vitamin D Trial.
“At the moment, we don’t have plans to start another vitamin D trial, but we are of course going to publish several other results from the Finnish Vitamin D Trial, for example effects [on] heart arrhythmias, infections, type 2 diabetes, falls and fractures, pain, [and] mood changes.”
