7th International Vitamin D Conference – Minimum, Maximum, Optimum – Evidas 2025, Warsaw: Key takeaways according to Sun for Life

The 7th International Conference “Vitamin D – Minimum, Maximum, Optimum”, Evidas 2025, held in October in Warsaw at the Children’s Memorial Health Institute, brought together leading scientists from Europe and North America to discuss the latest discoveries concerning vitamin D and human health.

The meeting was chaired and co-organised by Dr. hab. Paweł Płudowski, Professor at the Children’s Memorial Health Institute, whose long-standing commitment to organizing the Warsaw conferences has created an international platform for knowledge exchange.

The conference was rich in engaging presentations and new research findings. The program included as many as 26 lectures, all of which are listed at the end of this article. In the summary below, we focus on those lectures and some of their parts that particularly captured our attention from the Sun for Life perspective. We also share reflections on the current international recommendations regarding vitamin D, how they are evolving, what they mean in practice, and how they fit into the broader picture of the relationship between sunlight and human well-being.

Prof. Anastasios G. Pittas – Vitamin D Supplementation: Who Benefits? Current Endocrine Society 2024 Guidelines

Professor Anastasios G. Pittas from Tufts Medical Centre in Boston began his lecture by clarifying a key point: “The 2024 Endocrine Society guideline replaces the 2011 one.” He added that “the Endocrine Society has formally retired the previous guidelines.”

As he explained, the new recommendations do not deny the importance of vitamin D but update the approach to its use based on the most reliable and current evidence. “Children and adults should follow the recommended daily allowance established by the National Academy of Medicine,” he said.

Contrary to some interpretations circulating in public discussions, Professor Pittas emphasised that the document does not discourage supplementation: “Nowhere in the guideline does it say that you should not take vitamin D – that is a misinterpretation.” He stressed that the goal is not to abandon supplementation but to shift the focus: “Why not just make sure people get vitamin D? Let’s not focus only on testing, but ensure that everyone gets enough to avoid deficiency.”

Professor Pittas reminded the audience that the expert panel based its conclusions on the highest quality evidence available: “We focused on outcomes supported by high-quality randomised controlled trials,” he said. “We did not make recommendations based solely on observational data.”

Explaining the methodology, he added, “We reviewed the range of doses used in clinical trials and calculated a weighted average daily dose.”

He also underlined that the guidelines promote a rational, balanced approach to supplementation rather than fear-based messages: “We also want to emphasise that the guidelines do not state that higher doses are unsafe, they simply conclude that in most cases, they are unnecessary.”

In the following part of his presentation, Professor Pittas presented the main points of the new Endocrine Society 2024 guidelines, developed on the basis of current clinical data. According to these recommendations, the suggested daily intake for the general population remains aligned with the National Academy of Medicine: 600 IU per day for individuals aged 1–70, and 800 IU per day for those over 70.

However, the expert panel supports empirical vitamin D supplementation – that is, supplementation based on clinical experience and population data, without prior measurement of serum 25(OH)D – in selected risk groups: in children and adolescents (to prevent rickets and respiratory infections), in older adults (to potentially reduce all-cause mortality), in pregnant women (to lower the risk of preeclampsia, preterm birth, and perinatal mortality), and in individuals with prediabetes (to reduce the risk of progression to type 2 diabetes).

It was also emphasised that in adults over 50 who require treatment with vitamin D, daily supplementation is preferred over intermittent high-dose regimens. The panel does not recommend routine measurement of serum 25(OH)D in healthy individuals who do not have clinical indications for testing, such as hypocalcemia.

Prof. Stefan Pilz – The 2024 Endocrine Society Guidelines through the Eyes of an Endocrinologist, Clinician, and Scientist

From the very beginning of his presentation, Professor Stefan Pilz from the Medical University of Graz came across as a voice of reason and scientific balance. Instead of enthusiasm for the new guidelines, Pilz expressed a healthy scepticism toward applying them too literally. He emphasised that the guidelines should serve as an aid, not as an absolute directive. “Why not just give people vitamin D? Let’s not focus only on testing, but make sure everyone is taking it and avoiding deficiency,” he said.

Professor Pilz pointed out that although evidence-based medicine remains the cornerstone of modern practice, it should never be separated from the clinical context. “Evidence-based medicine is essential,” he said, “but we must remember that the study design matters.” As he explained, many large population analyses have produced inconclusive results because they included individuals who were not vitamin D deficient or who received doses too low to have an effect. “If you start with participants who already have normal vitamin D levels, you cannot expect to see meaningful outcomes,” he remarked. He also stressed that research findings must always be interpreted “within the appropriate biological and clinical context.”

His words also clearly defended clinical flexibility and the role of physician experience: “We all agree that evidence-based medicine is important, but clinical judgment must also be applied.” He added that moderate doses of vitamin D remain safe: “There is no evidence that doses up to 4,000 IU per day are harmful.”

He concluded his lecture by reminding the audience, “Guidelines are a tool. They help, but they do not replace clinical thinking.”

Prof. Michał Żmijewski – The 2024 Endocrine Society Guidelines from a Non-Clinician’s Perspective

Professor Michał Żmijewski from the Medical University of Gdańsk is a biologist whose main research areas include dermatoendocrinology and vitamin D biology. In his presentation, he discussed the new 2024 Endocrine Society guidelines, showing how they can be interpreted scientifically in a broader population and geographical context.

He began by clarifying the scope of the document: “It is important to remember that these recommendations are addressed to healthy individuals.” As he noted, a large part of the guidelines focuses on reducing unnecessary diagnostics: “Almost half of the document’s statements say that routine vitamin D testing is not recommended.”

He also pointed out an important linguistic shift: “You will not find the words ‘normal’ or ‘deficiency’ anywhere in the entire document. This is a significant change compared to previous recommendations.”

Later in his talk, Professor Żmijewski emphasised that supplementation should take into account local factors, both geographical and cultural. “Dosing must reflect local conditions, latitude, climate, and lifestyle,” he explained.

He highlighted that in Poland, due to its geographical position, cutaneous vitamin D synthesis is impossible for a large part of the year. “Poland lies on the 50th parallel, which means that for much of the year, even if we want to, we are unable to produce vitamin D in the skin.” In countries with limited sunlight, such as Scandinavia or Canada, requirements are therefore higher, while in southern regions, preventive doses may be lower.

Summing up this part of his lecture, he stated: “This shows that one universal recommendation cannot be applied worldwide. It must be adjusted to latitude, climate, and lifestyle.”

The professor also referred to the importance of light exposure in daily human functioning, emphasising that even brief skin contact with sunlight has physiological significance, though the efficiency of synthesis depends on many factors.

Prof. Michael F. Holick – The 2024 Endocrine Society Guidelines: An Objective or a Subjective Assessment of Their Clinical Usefulness

In his lecture, Professor Michael F. Holick reminded the audience that while numbers and guidelines may change, human biology and our relationship with sunlight remain constant. As he stated, “The sun will always remain the major natural source of vitamin D.”

He began by emphasising that “about 90 to 95 percent of the vitamin D your body gets is produced from sensible sun exposure.” He explained that “sensible exposure means brief periods in the sun that do not cause burning.”

Describing the process of cutaneous vitamin D synthesis, he said, “A UVB photon converts 7-dehydrocholesterol to previtamin D₃, which then thermally isomerises to vitamin D₃ and becomes the active hormone through subsequent transformations in the liver and kidneys.”

He also pointed out that “if you apply sunscreen to all exposed skin, you block vitamin D production by about 95 to 98 percent.”

To illustrate how efficient this process is, he cited the results of his own studies: “When we exposed healthy adults to UVB radiation in a tanning bed delivering one minimal erythemal dose, they produced between 15,000 and 20,000 international units of vitamin D.”

He added that “the recommended 600 to 800 IU per day can easily be produced with minimal sun exposure.”

Professor Holick also highlighted the importance of geographic latitude: “Above roughly 32 degrees north latitude, you cannot make any significant vitamin D in your skin during the winter months.”

At the same time, he noted that even older adults retain the capacity to produce vitamin D: “We showed more than 40 years ago that ageing reduces the skin’s capacity to produce vitamin D by about 75 percent, but the skin still has such an enormous potential that even elderly people can make it.”

He further explained that the time of exposure should be adjusted to skin phototype: “For me, with skin type II, about 15 minutes of exposure two or three times a week to the arms, legs, abdomen, and back is enough, but you should always protect the face because it is the most exposed area.”

In conclusion, he stressed: “The sun is not our enemy, overexposure is.” And added, “Sensible sun exposure remains the simplest and most natural way to maintain adequate vitamin D levels.”

Dr hab. Paweł Płudowski, Professor at the Children’s Memorial Health Institute – Cumulative Doses Available in Poland: Proposed Indications

Professor Paweł Płudowski from the Children’s Memorial Health Institute in Warsaw opened the session devoted to cumulative doses of vitamin D by emphasising that the key goal is not only to identify deficiency, but to correct it effectively. “It is not just about diagnosing a deficiency, but about successfully correcting it,” he said.

He pointed out that in clinical practice, there is an increasing need to raise vitamin D levels quickly, particularly in older adults, patients recovering from infections, and those with obesity or chronic diseases. As he explained, “We may consider using loading doses in selected clinical cases, but always with safety in mind.”

He reminded the audience that in Poland, preparations with varying vitamin D content – from 50,000 to 200,000 IU – are available and can be administered according to different regimens: as a single dose, weekly, or biweekly, depending on individual patient needs. “Obesity is one of the most important factors requiring an increased intake of vitamin D,” he noted.

In the second part of his lecture, Professor Płudowski referred to the broader health context, reminding participants that vitamin D deficiency has consequences that extend beyond the skeletal system. “Vitamin D deficiency increases the risk of developing many diseases and complications.” As he added, prevention should not be limited to supplementation, but should also include lifestyle, proper nutrition, physical activity, and sunlight exposure.

He concluded his talk with a reflection that captured the essence of the entire session: “We often hear that our grandparents didn’t know what vitamin D was, yet they lived and worked. But the question is, at what age did they die, and from what diseases?”

His presentation was one of those moments in the conference that carried an important message: education and public awareness are crucial so that prevention becomes a daily habit, not merely an intervention in times of health crisis.

Dr Mateusz Babicki – The Young, Active, Working Patient in Primary Care: Do They Remember Vitamin D?

Dr Mateusz Babicki from the Wroclaw Medical University began his lecture by noting that family doctors are increasingly seeing young, professionally active patients who may also suffer from vitamin D deficiency. He pointed out that this group, absorbed by professional and family responsibilities, rarely spends time outdoors, lacks regular physical activity, and often forgets about daily supplementation. “These are people who spend most of the day at work, in closed spaces. Although they are healthy, they still belong to the risk group for vitamin D deficiency.”

He emphasised that in primary healthcare settings, physicians cannot order vitamin D level testing under public reimbursement, which limits preventive action. “In primary care, we are not allowed to order this test within the reimbursement system, which makes diagnostics more difficult. However, it is worth encouraging patients to do it privately,” he said. “It is an investment in one’s health that helps determine whether prevention or actual treatment is needed.”

In the next part of his presentation, Dr Babicki highlighted the differences between dietary supplements and medicinal products containing vitamin D. “Poland is among the top European countries in terms of the number of people taking supplements, but that doesn’t mean we are supplementing properly,” he said. He underlined that supplements vary in quality and their contents are not always controlled, which is why, in treating deficiency, it is better to use preparations registered as medicinal products.

He also presented a case study of a 34-year-old female office worker suffering from chronic fatigue and recurrent infections. Her vitamin D level was only 6 ng/ml. After two months of supplementation, it increased to 29 ng/ml, resulting in a noticeable improvement in her well-being. As he pointed out, this example shows that even young and seemingly healthy individuals can suffer from a serious deficiency if their lifestyle does not include sunlight exposure.

In conclusion, he stressed that treatment should combine pharmacotherapy and lifestyle changes: “We must not forget about physical activity, fresh air, and proper nutrition, because even the best medicine cannot replace a healthy lifestyle.”

Prof. Waldemar Misiorowski – Under Special Supervision: Vitamin D in High-Risk Patient Groups

Professor Waldemar Misiorowski from the Centre of Postgraduate Medical Education in Warsaw began his presentation by reminding the audience that the problem of vitamin D deficiency is not limited to children. “Vitamin D is needed at every age, not only in infants and children,” he emphasised.

He noted that only in recent decades has the importance of vitamin D been recognised in the context of population ageing and chronic diseases. “For about 50 years, no one was really interested in vitamin D, until a new pandemic affecting the ageing population drew our attention back to it,” he observed.

Professor Misiorowski reminded us that vitamin D deficiency is one of the key factors accelerating the development of senile osteoporosis, which differs from postmenopausal osteoporosis. “Vitamin D deficiency plays a fundamental role in the development of age-related osteoporosis, unlike postmenopausal osteoporosis, which results from a deficiency of sex hormones.”

He also pointed out that obesity is one of the most important risk factors for vitamin D deficiency. “Obesity is one of the main risk factors for vitamin D deficiency, because vitamin D is fat-soluble and stored in adipose tissue,” he explained. In obese individuals, there is not only an increased demand for vitamin D but also a reduced efficiency in its utilisation by the body.

Professor Misiorowski further reminded that maintaining adequate vitamin D levels supports glucose metabolism and may play a role in preventing metabolic syndrome and type 2 diabetes. As he emphasised, vitamin D is not a drug, but its deficiency increases the risk of these disorders.

His lecture was a clear reminder that vitamin D deficiency is not only a pediatric issue, but a growing concern for the entire ageing population, where prevention should come before treatment.

Prof. Carsten Carlberg – Vitamin D Signalling Pathways In Vivo: The Impact of the Vitamin D Response Index on Health and Disease

Professor Carsten Carlberg (University of Eastern Finland, ERA Chair at the Polish Academy of Sciences in Olsztyn) delivered a lecture that elegantly combined molecular biology, genetics, and the philosophy of health. At the very beginning, he reminded the audience: “Vitamin D is a transcriptional regulator that directly or indirectly controls the expression of more than one thousand human genes.”

With this statement, he introduced the concept of vitamin D as a genetic regulator, not merely a vitamin but a biological light signal transmitted to our DNA. He explained that the human response to vitamin D supplementation differs between individuals and depends on cellular sensitivity to the vitamin D signal, known as the Vitamin D Response Index. “We do not all respond in the same way to the same vitamin D dose. The response is personal and depends on genetics and epigenetics.”

Professor Carlberg emphasised that individuals with a low response index may require higher doses or longer sunlight exposure to achieve the same biological effect as those with a high response index. He noted that this approach opens new opportunities for research into personalised vitamin D supplementation, where what matters is not only how much vitamin D is taken, but how efficiently the body can use it.

“We are the product of our genes, but our genes are shaped by our lifestyle and our environment, especially by sunlight,” he continued. He explained that human evolution took place in full sunlight. “Our genome was shaped under the sun. Only recently have we started to live indoors, and our biology has not yet adapted to that.”

In this context, he discussed how modern lifestyle, lack of movement, insufficient sleep, limited exposure to natural light, and reduced social interaction disrupt our biological clock and accelerate ageing. Showing a comparison between chronological and biological age, he concluded: “The difference between chronological and biological age depends on how we live, on sleep, diet, physical activity, social connections, and exposure to light that keeps our circadian rhythm in sync.”