PisaczekSearch
文AEN-US
PolskiEnglish (UK)English (US)EspañolPortuguês (Brasil)DeutschFrançaisItalianoУкраїнська中文（简体）한국어Bahasa IndonesiaРусскийالعربيةहिन्दी
Vitamins and minerals

Vitamin D3 levels don’t rise despite taking supplements — what’s going wrong?

Sources: 8 · Article: 14 199 characters

Jan Jaśkowski explains that low vitamin D levels despite supplementation may be due to the body using it up quickly or poor absorption from the intestines into the blood.

  • According to him, polyunsaturated fatty acids may reduce vitamin D absorption by as much as 30%, and some supplements may contain less active ingredient than stated on the label.
  • Calcium deficiency and low levels of magnesium and vitamin K2 may weaken calcium balance and affect vitamin D3 levels.
  • Jerzy Jaśkowski believes that a weight-loss or vegetable-based diet usually limits the absorption of vitamin D supplements and recommends taking vitamin D3 with K2.

What the authors write

Jan Jaśkowski

Low levels despite supplementation may be due to how quickly the body uses up the vitamin or to poor absorption from the intestines into the blood.

„This is a common problem. It has two main causes: first, how quickly the body “uses up” this vitamin, and second, how well vitamin D3 is absorbed from the intestines into the blood. Let’s look at both mechanisms today to better understand how this situation can be addressed.”To częsty problem. Ma on dwie główne przyczyny: pierwszą jest tempo „zużywania” tej witaminy przez organizm, a drugą — stopień wchłaniania witaminy D3 z jelit do krwi. Przyjrzyjmy się dzisiaj obu tym mechanizmom, aby lepiej zrozumieć, jak można zaradzić tej sytuacji.
Dlaczego masz niski poziom witaminy D3 mimo suplementacji? — Moja Apteczka
Jan Jaśkowski

Even the best supplementation will not work if the body cannot absorb the vitamin.

„The second main reason for low blood vitamin D levels despite supplementation is how well it is absorbed from the digestive tract into the blood. Even the best supplementation will not work if your body cannot absorb it.”Drugą główną przyczyną niskiego stężenia witaminy D we krwi mimo jej suplementacji jest stopień jej wchłaniania z przewodu pokarmowego do krwi. Nawet najlepsza suplementacja nie zadziała, jeśli Twój organizm nie będzie w stanie jej przyswoić.
Dlaczego masz niski poziom witaminy D3 mimo suplementacji? — Moja Apteczka
Jan Jaśkowski

Polyunsaturated fatty acids may reduce vitamin D absorption by as much as 30%.

„It has been shown that polyunsaturated fatty acids—linolenic acid and linoleic acid (omega-3 and omega-6 fatty acids)—reduce vitamin D absorption by as much as 30%! These fats are found mainly in plants—rapeseed, soy, and so on (except for olive oil and coconut oil)—as well as in poultry and pork.”Udowodniono, że wielonienasycone kwasy tłuszczowe — kwas linolenowy i kwas linolowy (kwasy omega-3 i omega-6) — zmniejszają nawet o 30% wchłanianie witaminy D! Te tłuszcze występują głównie w roślinach — rzepaku, soi itp. (poza oliwą z oliwek i olejem kokosowym) oraz w drobiu i wieprzowinie.
Dlaczego masz niski poziom witaminy D3 mimo suplementacji? — Moja Apteczka
Jan Jaśkowski

Some supplements may not contain the amount of active ingredient stated on the label.

„Unfortunately, some dietary supplements do not contain the declared amounts of active ingredients. There are thirty thousand companies in Poland that make and sell dietary supplements. Unfortunately, among such a large group there are dishonest manufacturers. That is why it is so important to entrust your health only to trusted sources that are transparent and use tested raw materials.”Część suplementów diety niestety nie zawiera deklarowanych ilości substancji aktywnych. W Polsce funkcjonuje trzydzieści tysięcy firm produkujących i sprzedających suplementy diety. Niestety w tak dużym gronie znajdą się nieuczciwi producenci. Dlatego tak ważne jest, by swoje zdrowie powierzać wyłącznie sprawdzonym źródłom, które nie boją się transparentności i korzystają z przebadanych surowców.
Dlaczego masz niski poziom witaminy D3 mimo suplementacji? — Moja Apteczka
Jan Jaśkowski

Calcium deficiency and low levels of magnesium and vitamin K2 may weaken calcium balance and lead to lower vitamin D3 levels.

„If you are deficient in these nutrients, your calcium balance weakens, which directly contributes to lower vitamin D3 levels. What is more, magnesium itself is essential for the synthesis and metabolism of vitamin D! Unfortunately, calcium and magnesium deficiencies are very common today.”Jeśli Ci ich brakuje, Twoja gospodarka wapniowa słabnie, a to bezpośrednio wpływa na obniżenie i niski poziom witaminy D3. Co więcej, sam magnez jest niezbędny do syntezy i metabolizowania witaminy D! Niestety, niedobory tych wapnia i magnezu są dziś bardzo powszechne.
Dlaczego masz niski poziom witaminy D3 mimo suplementacji? — Moja Apteczka
Jerzy Jaśkowski

Jerzy Jaśkowski claims that a weight-loss or vegetable-based diet usually limits the absorption of vitamin D supplements.

„People who are trying to lose weight and follow a vegetable-based diet usually absorb supplements of this vitamin less well. Unfortunately for those who prefer convenience, immunity is mainly supported by this vitamin in the form of sulfate, which the body gets from sunlight. So, whether we like it or not, we have to sunbathe and ignore reports that the sun causes cancer.”Osoby odchudzające się i mające dietę warzywną mają zwykle ograniczone wchłanianie suplementów tej witaminy. Niestety dla wygodnickich, za odporność odpowiada głównie ta witamina w postaci siarczanu otrzymywana za pomocą słońca. Chcąc nie chcąc musimy się więc opalać i nie słuchać doniesień, że słońce powoduje raka.
Słoneczny dar natury - witamina D3
Jerzy Jaśkowski

Jerzy Jaśkowski believes that taking vitamin D3 on its own is a mistake and that it should be taken with vitamin K2.

„Despite knowing that vitamin D3 is a hormone, doctors still do not know that vitamin D3 should be given with vitamin K2. Taking vitamin D3 on its own is a basic mistake. Natural vitamin D is a sulfate and dissolves in water, unlike tablets, which dissolve in fat.”Pomimo wiedzy o witaminie D3 jako hormonie lekarze do dziś, nie wiedzą, że witaminę D3 należy podawać z witaminą K2. Przyjmowanie samej witaminy D3 jest szkolnym błędem. Naturalna witamina D jest siarczanem i rozpuszcza się w wodzie, w odróżnieniu od tabletek, które rozpuszczają się w tłuszczu.
Słoneczny dar natury - witamina D3
Jan Jaśkowski

The test most often measures calcidiol, the storage form of vitamin D, which is converted into its active form in the kidneys.

„We most often measure one of its metabolites in the blood—calcidiol (also known as 25-OH-D). It is produced in the liver and is the so-called storage form of vitamin D. Then, in the kidneys, it is converted into calcitriol (1.25-(OH)2-D), the active form.”Najczęściej sprawdzamy we krwi jeden z jej metabolitów – kalcydiol (inaczej 25-OH-D). Powstaje on w wątrobie i jest to tzw. forma magazynowa witaminy D. Następnie, w nerkach, jest on przekształcany do kalcytriolu (1.25-(OH)2-D), czyli formy aktywnej.
Dlaczego masz niski poziom witaminy D3 mimo suplementacji? — Moja Apteczka

Research from PubMed · Europe PMC

We selected 4 studies with the best, positive results. This is a selection, not a full review of all research.

Total number of studies on this topic in PubMed: 1 616.

A meta-analysis found that vitamin D3 raised total 25(OH)D levels more effectively than D2, including when taken daily.

Aim of the study: Two previous meta-analyses showed smaller differences between vitamin D3 and vitamin D2 in raising serum 25-hydroxyvitamin D [25(OH)D] and a consistently high heterogeneity when only including daily dosing studies.

Results: Overall, the results based on 20 comparative studies showed vitamin D3 to be superior to vitamin D2 in raising total 25(OH)D concentrations, but vitamin D2 and vitamin D3 had a similar positive impact on their corresponding 25(OH)D hydroxylated forms. The WMD in change in total 25(OH)D based on 12 daily dosed vitamin D2-vitamin D3 comparisons, analyzed using liquid chromatography-tandem mass spectrometry, was 10.39 nmol/L (40%) lower for the vitamin D2 group compared with the vitamin D3 group (95% confidence interval: -14.62, -6.16; I2 = 64%; P < 00001). Body mass index (BMI) appeared to be the strongest response modifier, reducing heterogeneity to 0% in both subgroups. The vitamin D2- and vitamin D3-induced change in total 25(OH)D lost significance predominantly in subjects with a BMI >25 kg/m2 (P = 0.99). However, information on BMI was only available in 13/17 daily dosed comparisons.

Comparison of the Effect of Daily Vitamin D2 and Vitamin D3 Supplementation on Serum 25-Hydroxyvitamin D Concentration (Total 25(OH)D, 25(OH)D2, and 25(OH)D3) and Importance of Body Mass Index: A Systematic Review and Meta-Analysis. · Adv Nutr 2024
Money for the studynot stated · European Commission, Biotechnology and Biological Sciences Research Council, European Food Safety Authority
Do the authors have ties to companies?yes — the authors reported it
Did a manufacturer help with the study?YES
Type of studycombined analysis of many studies (meta-analysis)

“Not stated” does not mean nobody paid — the database does not always record it.

A review found that taking 2000 IU of D3 daily may raise and maintain 25(OH)D levels in most adults.

Aim of the study: Vitamin D deficiency is considered a public health problem due to its worldwide high prevalence and adverse clinical consequences regarding musculoskeletal health. In addition, vitamin D may also be crucial for the prevention of certain extraskeletal diseases.

Results: In this brief narrative review, we outline and discuss recent advances regarding the scientific evidence arguing for a daily vitamin D supplementation with 2000 international units (IU) (50 µg) of vitamin D3 to prevent and treat vitamin D deficiency. According to data from randomized controlled trials (RCTs), such a dose may improve some health outcomes and is sufficient to raise and maintain serum 25(OH)D concentrations above 50 nmol/L (20 ng/mL) and above 75 nmol/L (30 ng/mL) in >99% and >90% of the general adult population, respectively. According to large vitamin D RCTs, there are no significant safety concerns in supplementing such a dose for several years, even in individuals with an already sufficient vitamin D status at baseline. A daily vitamin D supplementation with 2000 IU (50 µg) may be considered a simple, effective, and safe dosage to prevent and treat vitamin D deficiency in the adult general population.

Vitamin D Supplementation: A Review of the Evidence Arguing for a Daily Dose of 2000 International Units (50 µg) of Vitamin D for Adults in the General Population. · Nutrients 2024
Money for the studynot stated
Do the authors have ties to companies?yes — the authors reported it
Did a manufacturer help with the study?YES
Type of studydiscussion of other studies

“Not stated” does not mean nobody paid — the database does not always record it.

In a small study of people with Parkinson’s disease and vitamin D3 deficiency, supplementation significantly increased 25(OH)D3 levels.

Aim of the study: Parkinson's disease (PD) patients frequently exhibit vitamin D deficiency and an imbalance in T helper 17 (Th17) and regulatory T (Treg) cells, which may contribute to disease pathogenesis. Preclinical evidence suggests vitamin D regulates Th17/Treg balance, but the therapeutic effects of supplementation in PD remain unestablished.

Results: Vitamin D3 supplementation significantly increased 25(OH)D3 levels (p < 0.05), reduced Th17 cells (4.62 ± 1.09 to 3.25 ± 1.14, p = 0.003), and elevated Tregs (3.25 ± 0.90 to 4.52 ± 0.95, p = 0.003). Motor function (UPDRS and UPDRS-III) improved in the vitamin D3 group (p < 0.001), while no changes were observed in the placebo group. This preliminary study suggests that vitamin D3 supplementation may restore Th17/Treg balance and potentially alleviate motor symptoms in vitamin D-deficient PD patients, indicating a possible therapeutic strategy.Trial registration: ClinicalTrials.gov: NCT:06539260. Registered 05 August 2024 - Retrospectively registered, https://clinicaltrials.gov/study/NCT06539260 .

Impact of vitamin D3 supplementation on motor functionality and the immune response in Parkinson's disease patients with vitamin D deficiency. · Sci Rep 2025
Money for the studygovernment, public institutions · Health Commission of Anhui Province, the Anhui Provincial Key Research and Development Plan
Do the authors have ties to companies?no — the authors say so
Did a manufacturer help with the study?NO
Type of studystudy with random allocation to groups (RCT)

“Not stated” does not mean nobody paid — the database does not always record it.

In children, supplementation with 400 or 800 IU per day for 8 weeks increased 25(OH)D3 levels, with a greater increase seen with 800 IU.

Aim of the study: Vitamin D deficiency is common among children in high-latitude regions. However, region-specific intervention strategies remain unclear. Few studies have simultaneously examined outdoor activity intervention, vitamin D supplementation, and genetic polymorphisms. Thus, this study aimed to explore feasible intervention strategies for children in Northeast China.

Results: Outdoor activity duration increased by 11 min/d, and estimated vitamin D production from UV increased by 60.73 IU/d, but serum 25(OH)D3 did not change significantly (18.52 ± 4.07 vs. 18.25 ± 3.11 ng/ml); this change was not associated with outdoor time, UV intensity, or calculated vitamin D production from UV. In the supplementation trial, serum 25(OH)D3 increased by 8.82 ± 7.53 ng/ml in the 400 IU/d group and 15.06 ± 9.40 ng/ml in the 800 IU/d group. Total vitamin D intake (diet + supplement) was estimated to require at least 733.21 IU/d to achieve serum 25(OH)D3 ≥30 ng/ml. Children with CT/TT genotypes (rs1562902) and AG/GG genotypes (rs10741657) showed a trend of lower sensitivity to supplementation. Increasing outdoor activity did not improve vitamin D status in children in Northeast China, but daily supplementation was effective. Dietary vitamin D intake and SNPs should be considered when formulating individualized supplementation doses.

Intervention methods and influencing factors of vitamin D deficiency in Northeast China: a self-controlled trial and randomized controlled trial study. · Front Nutr 2026
Money for the studygovernment, public institutions · Natural Science Foundation of Shanghai, the 2024 hospital-level talent project of Zhoupu affiliated to Shanghai University of Medicine and Health Sciences
Do the authors have ties to companies?no — the authors say so
Did a manufacturer help with the study?NO
Type of studystudy with random allocation to groups (RCT)

“Not stated” does not mean nobody paid — the database does not always record it.

Perspectives and opinion materials

The content below presents the authors’ opinions, interpretations and hypotheses. It is not treated as equal to scientific studies and systematic reviews.

Orthomolecular Medicine News Service Opinion material
„3.6 Insufficiency/Deficiency of Other Vitamins and Micronutrients Vitamin D metabolism is closely linked with other micronutrients, and deficiencies in these can exacerbate vitamin D resistance: Nutritional Deficiencies: A study examined the correlation between dietary intake of vitamin D and calcium and the prevalence of vitamin D deficiency. It emphasized that inadequate dietary sources, compounded by environmental toxins, can lead to significant health issues related to vitamin D metabolism (36). Vitamin C: Research indicates that vitamin C deficiency can impair the immune-modulating effects of vitamin D.”3.6 Insufficiency/Deficiency of Other Vitamins and Micronutrients Vitamin D metabolism is closely linked with other micronutrients, and deficiencies in these can exacerbate vitamin D resistance: Nutritional Deficiencies: A study examined the correlation between dietary intake of vitamin D and calcium and the prevalence of vitamin D deficiency. It emphasized that inadequate dietary sources, compounded by environmental toxins, can lead to significant health issues related to vitamin D metabolism (36). Vitamin C: Research indicates that vitamin C deficiency can impair the immune-modulating effects of vitamin D.
Understanding and Addressing Vitamin D Resistance: A Comprehensive Approach Integrating Genetic, Environmental, and Nutritional Factors
Orthomolecular Medicine News Service Opinion material
„Recommendations for Supplementation To combat widespread deficiency and optimize health outcomes, this review advocates for daily supplementation: Basic Prevention: 2000 IU/day (50 mcg/day) of vitamin D3 is effective in maintaining serum 25(OH)D levels above 30 ng/mL, reducing risks of deficiency-related diseases. Optimal Protection: A daily dose of 4000-6000 IU (100-150 mcg) of vitamin D3 is recommended to achieve serum levels between 40-70 ng/mL, providing enhanced protection against various adverse health outcomes. Heavy individuals may require up to 10,000 IU/d to maintain the same range of serum levels.”Recommendations for Supplementation To combat widespread deficiency and optimize health outcomes, this review advocates for daily supplementation: Basic Prevention: 2000 IU/day (50 mcg/day) of vitamin D3 is effective in maintaining serum 25(OH)D levels above 30 ng/mL, reducing risks of deficiency-related diseases. Optimal Protection: A daily dose of 4000-6000 IU (100-150 mcg) of vitamin D3 is recommended to achieve serum levels between 40-70 ng/mL, providing enhanced protection against various adverse health outcomes. Heavy individuals may require up to 10,000 IU/d to maintain the same range of serum levels.
Summary of Vitamin D: Evidence-Based Health Benefits and Recommendations for Population Guidelines

Pisaczek does not judge who is right. It shows what was written and where to read it. Every sentence above has its source.