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Re: Discussie over vitamine D

Geplaatst: 11 jan 2018, 11:24
door laura
High-Dose Vitamin D: Helpful or Harmful?
Karen E. Hansen

If the optimal serum 25(OH)D level for skeletal health is ≥30 ng/mL, then vitamin D insufficiency is widespread, affecting approximately 75% of adults based on a recent survey of over 20,000 Americans. However, after a comprehensive analysis of existing research studies, the Institute of Medicine recently concluded that nearly all individuals are vitamin D replete when their 25(OH)D levels are ≥20 ng/mL.

Furthermore, two recent publications challenge the belief that 25(OH)D levels >30 ng/mL are optimal for bone health. In a randomized, placebo-controlled trial, high-dose once yearly vitamin D therapy increased fractures and falls. The second study reported that high-dose vitamin D did not reduce levels of parathyroid hormone or bone resorption among adults with 25(OH)D levels <32 ng/mL at baseline. It is time to question whether serum 25(OH)D levels ≥30 ng/mL are necessary for all individuals.

Re: Discussie over vitamine D

Geplaatst: 11 jan 2018, 11:25
door laura
BB1100XX schreef:
05 dec 2017, 20:40
Dat ben ik eindelijk aan het overwinnen!
time for a change!
Wat goed!

Re: Discussie over vitamine D

Geplaatst: 11 jan 2018, 11:28
door laura
Association Between Calcium or Vitamin D Supplementation and Fracture Incidence in Community-Dwelling Older Adults
A Systematic Review and Meta-analysis | Jia-Guo Zhao, Xian-Tie Zeng, Jia Wang, Lin Liu

Importance The increased social and economic burdens for osteoporosis-related fractures worldwide make the prevention of such injuries a major public health goal. Previous studies have reached mixed conclusions regarding the association between calcium, vitamin D, or combined calcium and vitamin D supplements and fracture incidence in older adults.

Objective To investigate whether calcium, vitamin D, or combined calcium and vitamin D supplements are associated with a lower fracture incidence in community-dwelling older adults.

Data Sources The PubMed, Cochrane library, and EMBASE databases were systematically searched from the inception dates to December 24, 2016, using the keywords calcium, vitamin D, and fracture to identify systematic reviews or meta-analyses. The primary randomized clinical trials included in systematic reviews or meta-analyses were identified, and an additional search for recently published randomized trials was performed from July 16, 2012, to July 16, 2017.

Study Selection Randomized clinical trials comparing calcium, vitamin D, or combined calcium and vitamin D supplements with a placebo or no treatment for fracture incidence in community-dwelling adults older than 50 years.

Data Extraction and Synthesis Two independent reviewers performed the data extraction and assessed study quality. A meta-analysis was performed to calculate risk ratios (RRs), absolute risk differences (ARDs), and 95% CIs using random-effects models.

Main Outcomes and Measures Hip fracture was defined as the primary outcome. Secondary outcomes were nonvertebral fracture, vertebral fracture, and total fracture.

Results A total of 33 randomized trials involving 51 145 participants fulfilled the inclusion criteria. There was no significant association of calcium or vitamin D with risk of hip fracture compared with placebo or no treatment (calcium: RR, 1.53 [95% CI, 0.97 to 2.42]; ARD, 0.01 [95% CI, 0.00 to 0.01]; vitamin D: RR, 1.21 [95% CI, 0.99 to 1.47]; ARD, 0.00 [95% CI, −0.00 to 0.01]. There was no significant association of combined calcium and vitamin D with hip fracture compared with placebo or no treatment (RR, 1.09 [95% CI, 0.85 to 1.39]; ARD, 0.00 [95% CI, −0.00 to 0.00]). No significant associations were found between calcium, vitamin D, or combined calcium and vitamin D supplements and the incidence of nonvertebral, vertebral, or total fractures. Subgroup analyses showed that these results were generally consistent regardless of the calcium or vitamin D dose, sex, fracture history, dietary calcium intake, and baseline serum 25-hydroxyvitamin D concentration.

Conclusions and Relevance In this meta-analysis of randomized clinical trials, the use of supplements that included calcium, vitamin D, or both compared with placebo or no treatment was not associated with a lower risk of fractures among community-dwelling older adults. These findings do not support the routine use of these supplements in community-dwelling older people.

Re: Discussie over vitamine D

Geplaatst: 08 mar 2019, 12:03
door laura
hallo Eekhoorn,

Kun jij iets vertellen over de huidige stand van zaken rond vitamine D?
Wat is bijvoorbeeld een veilige dosis?
En hoe zit het met de halfwaardetijd?

Ik las van iemand dat zij 5000 IE per dag slikte.
Is dat niet heel veel?

Re: Discussie over vitamine D

Geplaatst: 08 mar 2019, 13:29
door laura
Patient education: Vitamin D deficiency (Beyond the Basics)

Author: Marc K Drezner, MD
Section Editor: Clifford J Rosen, MD
Deputy Editor: Jean E Mulder, MD

Contributor Disclosures
All topics are updated as new evidence becomes available and our peer review process is complete.
Literature review current through: Feb 2019. | This topic last updated: Feb 08, 2019.


Vitamin D plays an important role in many places throughout the body, including the development and calcification of the bones.

Adequate exposure to sunlight and the use of dairy products with vitamin D have significantly reduced the incidence of vitamin D deficiency. However, vitamin D deficiency is still a common problem in many populations, particularly older adults.

This topic reviews the major causes of vitamin D deficiency, including how it is diagnosed and treated, and safe ways to prevent vitamin D deficiency.


Vitamin D is an oil-soluble vitamin that has several important functions in the body:

●It helps to absorb dietary calcium and phosphorus from the intestines.

●It suppresses the release of parathyroid hormone, a hormone that causes bone resorption.

Through these actions, vitamin D keeps the calcium and phosphate levels in the blood normal, thereby promoting bone health. Vitamin D may have other benefits, such as improving muscle and immune function, but these areas require more research.

Natural sources of vitamin D — Vitamin D is made in the skin under the influence of sunlight. The amount of sunlight needed to synthesize adequate amounts of vitamin D varies, depending upon the person's age, skin color, sun exposure, and underlying medical problems. The production of vitamin D from the skin decreases with age. In addition, people who have darker skin need more sun exposure to produce adequate amounts of vitamin D, especially during the winter months.

Another important source of vitamin D is foods, where it may occur naturally (in fatty fish, cod liver oil, and [to a lesser extent] eggs). In the United States, commercially fortified cow's milk is the largest source of dietary vitamin D, containing approximately 100 international units (2.5 micrograms) of vitamin D per 8 ounces. Vitamin D intake, in international units, can be estimated by multiplying the number of cups of milk consumed per day by 100 (two cups milk = 200 international units vitamin D). In other parts of the world, cereals and bread products are often fortified with vitamin D.

Although vitamin D is found in cod liver oil, some fish oils also contain high doses of vitamin A. Excessive vitamin A intake can be associated with side effects, including liver damage and fractures.


The main reasons for low levels of vitamin D are:

●Lack of vitamin D in the diet, often in conjunction with inadequate sun exposure

●Inability to absorb vitamin D from the intestines

●Inability to process vitamin D due to kidney or liver disease

Inadequate intake — Infants, children, and older adults are at risk for low vitamin D levels because of inadequate vitamin D intake. Human breast milk contains low levels of vitamin D, and most infant formulas do not contain adequate vitamin D. Older adults often do not consume enough vitamin D rich foods, and even when they do, absorption may be limited.

Inadequate sun exposure — Parents of infants and children are often advised to keep their child out of the sun, which reduces vitamin D synthesis from the skin. Exposure to the sun is not recommended as a source of vitamin D for infants and children, due to the potential long-term risks of skin cancer. (See "Patient education: Sunburn (Beyond the Basics)".)

Adults who have limited sun exposure are also at increased risk of vitamin D deficiency, especially if their skin is dark. In addition, reduced amounts of vitamin D are made in the skin and stored in the body as we age. This is especially true in the winter months in some northern areas, such as Boston, Massachusetts and Edmonton, Alberta, where the skin virtually ceases to produce vitamin D between October and April. In the summer months, the use of sunscreen limits vitamin D synthesis.

Diseases or surgery that affect fat absorption — Certain diseases affect the body's ability to absorb adequate amounts of vitamin D through the intestinal tract. Examples of these include celiac disease, Crohn's disease, and cystic fibrosis.

Surgery that removes or bypasses portions of the stomach or intestines can also lead to low vitamin D levels. An example of this type of surgery is gastric bypass. (See "Patient education: Weight loss surgery and procedures (Beyond the Basics)".)

Kidney and liver disease — The liver and kidney have important enzymes that change vitamin D from sun-exposed skin or food to the biologically active form of vitamin D. People with chronic kidney and liver disease are at increased risk of low active vitamin D levels because they have decreased levels of these enzymes.

Less common causes of vitamin D deficiency include familial or acquired diseases that impair the enzymes in the liver or kidney that create the biologically active form of the vitamin. This results in inadequate amounts of active vitamin D.


The most serious complications of vitamin D deficiency are low blood calcium (hypocalcemia), low blood phosphate (hypophosphatemia), rickets (softening of the bones during childhood), and osteomalacia (softening of the bones in adults). However, these complications have become less common over time because many foods and drinks have added vitamin D.

"Subclinical" vitamin D deficiency or vitamin D insufficiency is common and is defined as a lower than normal vitamin D level that has no visible signs or symptoms. However, vitamin D insufficiency is often associated with reduced gastrointestinal calcium absorption, decreased bone density (osteopenia or osteoporosis), and, in some cases, a mild decrease of the blood calcium level, elevated parathyroid hormone (which accelerates bone resorption), an increased risk of falls, and possibly fractures, all of which can seriously affect a person's quality of life.

Thus, identifying and treating vitamin D insufficiency or deficiency is important to maintain bone strength. Treatment may even improve the health of other body systems, such as the immune, muscular, and cardiovascular systems, although more research is needed in these areas.


A low vitamin D level can be diagnosed with a blood test called 25-hydroxyvitamin D or 25(OH)D (OH = hydroxy, D = vitamin D). Although there is no formal definition of vitamin D deficiency, some groups use the following values in adults:

●A normal level of vitamin D is defined as a 25(OH)D concentration greater than 30 ng/mL (75 nmol/L)

●Vitamin D insufficiency is defined as a 25(OH)D concentration of 20 to 30 ng/mL (50 to 75 nmol/L)

●Vitamin D deficiency is defined as a 25(OH)D level less than 20 ng/mL (50 nmol/L)

Although there are differences of opinion regarding the 25(OH)D levels that define vitamin D insufficiency and deficiency, most experts agree that levels lower than 20 ng/mL (50 nmol/L) are suboptimal for skeletal health.

Who needs testing for vitamin D? — Testing for vitamin D deficiency or insufficiency is not recommended for everyone but may be advised for people who are home bound or in a long-term care facility (eg, nursing home); if the person has a medical condition that increases the risk of vitamin D deficiency or insufficiency; and for anyone with osteoporosis or a past history of a low-trauma fracture (eg, fracture after fall from standing), low blood calcium (hypocalcemia), or phosphate (hypophosphatemia). (See "Patient education: Bone density testing (Beyond the Basics)" and "Patient education: Osteoporosis prevention and treatment (Beyond the Basics)".)


Vitamin D supplements — There are many types of vitamin D preparations available for the treatment of vitamin D deficiency or insufficiency. The two commonly available forms of vitamin D supplements are ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3). We suggest vitamin D3 when possible, rather than vitamin D2, because vitamin D3 is the naturally occurring form of the vitamin and it may raise vitamin D levels more effectively.

Dosing — The recommended dose of vitamin D depends upon the nature and severity of the vitamin D deficiency.

In people who do not have problems absorbing vitamin D:

●In people whose 25-hydroxyvitamin D (25[OH]D) is <10 ng/mL (25 nmol/L), treatment usually includes 50,000 international units (1250 micrograms) of vitamin D2 or D3 by mouth once or more per week for six to eight weeks, and then 800 to 1000 international units (20 to 25 micrograms), or more, of vitamin D3 daily thereafter.

●In people whose 25(OH)D is 10 to 20 ng/mL (25 to 50 nmol/L), treatment usually includes 800 to 1000 international units (20 to 25 micrograms) of vitamin D3 by mouth daily, usually for a three-month period. However, many individuals will need higher doses. The "ideal" dose of vitamin D is determined by testing the individual's 25(OH)D level and increasing the vitamin D dose if the level is not within normal limits. Once a normal level is achieved, continued therapy with 800 international units (20 micrograms) of vitamin D per day is usually recommended.

●In people whose 25(OH)D is 20 to 30 ng/mL (50 to 75 nmol/L), treatment with 600 to 800 international units (15 to 20 micrograms) of vitamin D3 by mouth daily may be sufficient to maintain levels in the target range.

●In infants and children whose 25(OH)D is <20 ng/mL (50 nmol/L), treatment usually includes 1000 to 2000 international units (25 to 50 micrograms) of vitamin D2 by mouth per day (depending on the child's age) for two to three months. Children with rickets (softening of the bones, which can be seen on an X-ray) may need higher doses of vitamin D and should have medical follow-up to ensure that the rickets resolves.

In people who have diseases or conditions that prevent them from absorbing vitamin D normally (eg, kidney or liver disease), the recommended dose of vitamin D will be determined on an individual basis.

In people whose vitamin D level is normal (>30 ng/mL [≥75 nmol/L]), a dose of 800 international units (20 micrograms) of vitamin D per day is usually recommended. (See 'Prevention of vitamin D deficiency' below.)

Do I need other vitamins or minerals? — During treatment for vitamin D deficiency, it is important to consume at least 1000 mg of calcium per day for premenopausal women and men and 1200 mg per day for postmenopausal women.

Calcium can be found in food sources (table 1) or dietary supplements (table 2). (See "Patient education: Calcium and vitamin D for bone health (Beyond the Basics)".)

Monitoring — A blood test is recommended to monitor blood levels of 25(OH)D three months after beginning treatment. The dose of vitamin D may need to be adjusted based on these results and subsequent blood levels of 25(OH)D obtained to assure that normal levels result from the adjusted dose.

Side effects — Side effects of vitamin D are uncommon unless the 25(OH)D level becomes very elevated (>100 ng/mL or 250 mmol/L) and the person is taking high dose calcium supplements. However, it is important to follow dosing instructions closely and to avoid taking multiple products that contain vitamin D (eg, multivitamin and vitamin D).

If 25(OH)D levels do become very elevated, complications such as high blood calcium levels or kidney stones can develop.


As mentioned previously, the amount of vitamin D you need per day to maintain a normal level of 25-hydroxyvitamin D (25[OH]D) depends upon your skin color, sun exposure, diet, and underlying medical conditions.

In general, adults are advised to take a supplement containing 800 international units (20 micrograms) of vitamin D per day to maintain a normal vitamin D level. Older people who are confined indoors may have vitamin D deficiency even at this intake level. (See 'Vitamin D supplements' above.)

All infants and children are advised to take a vitamin D supplement containing 400 international units (10 micrograms) of vitamin D, starting within days of birth. For infants and children, vitamin D is included in most nonprescription infant multivitamin drops. In some countries, it is possible to buy infant drops that contain only vitamin D. (See "Patient education: Breastfeeding guide (Beyond the Basics)" and "Patient education: Starting solid foods during infancy (Beyond the Basics)".)

Exposure to the sun or tanning beds is not recommended as a source of vitamin D, because of the risk of skin cancer.


Your health care provider is the best source of information for questions and concerns related to your medical problem.

This article will be updated as needed on our website ( Related topics for patients, as well as selected articles written for health care professionals, are also available. Some of the most relevant are listed below.

Patient level information — UpToDate offers two types of patient education materials.

The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.

Patient education: Vitamin D deficiency (The Basics)
Patient education: Osteoporosis (The Basics)
Patient education: Calcium and vitamin D for bone health (The Basics)
Patient education: Vitamin supplements (The Basics)
Patient education: Vitamin D for babies and children (The Basics)

Re: Discussie over vitamine D

Geplaatst: 23 jun 2019, 11:51
door laura
Martijn Katan op Facebook: ... 5980282159

Te weinig vitamine D is slecht voor je botten. Kan een tekort aan vitamine D ook hoge bloeddruk veroorzaken, of overgewicht, hart- en vaatziekten, griep, depressie, multiple sclerose, diabetes of astma?

Dat wordt wel gedacht.

Daarom laten sommige dokters bij veel patiënten vitamine D in het bloed bepalen. Maar die effecten van vitamine D zijn schijn. Het effect op hartinfarcten en beroertes bijvoorbeeld is getest in 21 experimenten bij 83.291 mensen. Daarvan kregen er 41.669 vitamine D en 41.622 een neppil. Effect: nul, niks, nihil.

Voor overgewicht, griep etc. werd ook nooit iets gevonden: ... l-het-idee.

Dokters moeten stoppen met vitamine D meten, het kost een vermogen en het zegt niets.

Barbarawi M et al. Vitamin D Supplementation and Cardiovascular Disease Risks in More Than 83 000 Individuals in 21 Randomized Clinical Trials: A Meta-analysis. JAMA Cardiol. 2019.
Quyyumi AA, Al Mheid I. The Demise of Vitamin D for Cardiovascular Prevention. JAMA Cardiol. 2019.

Re: Discussie over vitamine D

Geplaatst: 11 nov 2019, 21:18
door Eekhoorn
hallo Eekhoorn,

Kun jij iets vertellen over de huidige stand van zaken rond vitamine D?

Er zijn meer aanwijzingen dat associaties tussen allerlei gezondheidsproblemen enerzijds en vitamine D-gebrek anderzijds, géén causaal verband hebben. Zie bijvoorbeeld ... d=76716975:
It now seems safe to conclude that many prior epidemiological associations between vitamin D deficiency and adverse health outcomes were driven by unmeasured residual confounding or reverse causality.
Wat is bijvoorbeeld een veilige dosis?
Wat betreft de maximaal veilige dosis heeft de EFSA in 2012 een 'scientific opinion' uitgegeven. Voor volwassenen en kinderen vanaf 11 jaar wordt een maximum van 4000 IE/dag geadviseerd. Daarbij is overwogen dat bij onderzoek geen nadelige gevolgen zijn gezien bij doses tot 10.000 IE/dag. Dat daarbij toch voor 4000 IE/dag is gekozen, kun je zien als het in acht nemen van een 'veiligheidsmarge'. Zie

Voor kinderen van 1 tot en met 10 jaar geldt volgens dit stuk een geadviseerd maximum van 2000 IE/dag.
Voor kinderen tot 1 jaar is een apart advies gepubliceerd:
Ik las van iemand dat zij 5000 IE per dag slikte.
Is dat niet heel veel?
Dat is behoorlijk veel, maar waarschijnlijk niet zoveel dat het gevaar oplevert. Het is iets meer dan de 4000 IE/dag die de EFSA maximaal adviseert, maar zit nog ruim onder de 10.000 IE/dag. Het is waarschijnlijk wel zinloos zoveel te nemen.
En hoe zit het met de halfwaardetijd?
Die hangt af van de vitamine D 25OH-bloedspiegel: hoe hoger die is, hoe korter de halfwaardetijd. Dat komt doordat het enzym dat vitamine D afbreekt, actiever wordt naarmate de 25OH-spiegel hoger is. Voor 'normale' spiegels - zeg tussen de 50 en 80 nmol/L - is de halfwaardetijd van 25OH een week of vier.

Re: Informatie over vitamine D

Geplaatst: 06 mar 2020, 16:58
door laura
laura schreef:
13 mar 2015, 12:51
Nieuw licht op vitamine D, Herwaardering van een essentieel prohormoon, Jos P.M. Wielders, Frits A.J. Muskiet en Albert van de Wiel ... d/volledig

Orthomoleculair natuurarts geschrapt als spreker op huisartsencongres

De website kent kwakzalverarts Albert Van der Velde niet meer omdat de programmacommissie van Boerhaave Nascholing hem geschrapt heeft als spreker op het nascholingscongres Arts en Voeding. Dit Boerhaave-congres wordt op 29 mei gehouden, voor de vierde maal in het LUMC in Leiden. Boerhaave Nascholing, onderdeel van het het Leids Universitair Medisch Centrum (LUMC), organiseert wetenschappelijk cursussen voor artsen en medisch specialisten.

De Haarlemse orthomoleculaire en ayurvedische natuurarts Van der Velde zou 's middags tijdens een van de parallelsessies een lezing houden over “Leefstijl in de spreekkamer”.

Een brief van Nico Terpstra, huisarts en bestuurslid van de Vereniging tegen de Kwakzalverij (VtdK), maakte een einde aan deze orthomoleculaire propaganda-actie. “Misschien kunt u even zien op zijn website wie U hiermee in huis haalt, een erkende kwakzalver”, zo luidde het advies van Terpstra aan de organisatie Boerhaave Nascholing. “Zijn adviezen met betrekking tot vitamine D zijn bizar en stroken in het geheel niet met de richtlijnen van de Gezondheidsraad. Om uitgerekend deze man een podium te geven voor zijn aberrante visie op voeding en gezondheid is naar mijn mening raar en onwenselijk.”

Het antwoord op deze brief liet niet lang op zich wachten. “We willen niet dat de aandacht van dit congres verschuift naar de antecedenten van een inleider; in overleg met de congrescommissie is besloten dat de heer Van der Velde geen voordracht zal houden”, laat het hoofd van Boerhaave Nascholing in een antwoord aan Terpstra weten. Boerhaave heeft een andere spreker bereid gevonden een lezing te houden over het onderwerp “spreekkamer”.

Van der Velde lapt met zijn orthomoleculaire geloof adviezen van de Gezondheidsraad en van zijn eigen artsenclub NHG aan zijn laars. In september 2012 concludeerde de raad, op basis van de dan bekende wetenschappelijke literatuur, dat mensen met een lichte huid (van 4 tot 70 jaar), die dagelijks voldoende buiten komen en dus voldoende vitamine D aanmaken, geen extra vitamine D uit een supplement nodig hebben. Uitzonderingen zijn “mensen met een donkere huid, die lichaam bedekkende kleding dragen of weinig buitenkomen.”

Orthomoleculair huisarts Van der Velde adviseert zijn patiënten iets geheel anders. Zij moeten het hele jaar door “elke 2 weken 25.000 IE Vit D3 innemen, door middel van een beetje vloeistof.” Hij zegt zich te baseren op een wat hij omschrijft als een “zeer gedegen en kritisch rapport over de huidige aanbevelingen van de Gezondheidsraad”.

Dit rapport is geschreven door enkele orthomoleculaire gelovigen waaronder Frits Muskiet en Gert Schuitemaker, twee bekenden van de Vereniging tegen de Kwakzalverij. Muskiet werd in 2013 genomineerd voor de Meester Kackadorisprijs van de vereniging. Over vitamine-verkoper Schuitemaker is de afgelopen jaren ook enkele malen geschreven op deze website.

Met het schrappen van natuurarts Van der Velde lijkt de Boerhaave-organisatie haar zaakjes nog niet helemaal voor elkaar te hebben. Het 4e Boerhaave Arts en Voeding-congres is namelijk een initiatief van de Stichting Voeding Leeft, die zich afficheert als een “onafhankelijke stichting en netwerkorganisatie van professionals, die met passie voor voeding en leefstijl de wereld en de wetenschap volgen met een verwonderende blik”. Op de site van het artsencongres staat het logo van deze stichting naast dat van Boerhaave Nascholing.

Pikant genoeg is de geschrapte natuurarts bestuurssecretaris en medeoprichter van deze stichting. In de deelnemersraad (onduidelijk is wat deelnemers zijn, red.) van Voeding Leeft zitten bovendien enkele bekenden van de VtdK, namelijk de eerder genoemde Frits Muskiet en de eveneens verguisde Rogier Hoenders, een Groningse psychiater met kwakneigingen.

Nico Terpstra heeft hier Boerhaave Nascholing in een tweede brief op gewezen. “Bij het nader bestuderen van de website van de stichting Voeding Leeft - mede opgericht door collega Van der Velde, die u van de sprekerslijst heeft laten afvoeren - valt enkele namen van omstreden leden van de “deelnemersraad op”, schrijft Terpstra.

“Ik doel onder andere op Rogier Hoenders, psychiater van Lentis in Groningen. Hoenders is voorstander van integratieve psychiatrie en organiseert sinds 2002 succesvolle congressen in Groningen, waarbij relatief weinig psychiaters spreken, maar des te meer lama's ('tantric self-healing'), scheikundigen als Van der Greef (voorstander van 'personalised Chinese medicine') en Muskiet (voeding en psychiatrie) en paranormaal angehauchte denkers als Rupert Sheldrake en Martine Busch. Bij zijn laatste congres in 2012 haakten de meeste reguliere wetenschappelijke verenigingen af.”

“Ik noem verder Frits Muskiet, pathofysioloog van het Universitair Medisch Centrum Groningen. Muskiet (1950) heeft een warme belangstelling voor evolutionaire geneeskunde. Hij stelt dat terugkeer naar de leefstijl van onze paleolithische voorouders, zoals aangepast naar de cultuur van de 21ste eeuw, de enige effectieve manier is om typisch westerse ziektes te voorkómen. Hij ontkent het verband tussen roken en longkanker en is sinds vele jaren een onvermijdelijk spreker op alternatieve en orthomoleculaire congressen, zoals bijvoorbeeld die van Lentis in Groningen. Onbeschaamd vermeldt de RUG-website dat Muskiet ook docent 'basiscursus orthomoleculaire geneeskunde' is. Daarmee maakt Muskiet zich schuldig aan het kweken van steeds weer nieuwe kwakzalvers, die overal deficiënties ontdekken, zo niet goedschiks dan wel kwaadschiks.”

“Bij de Vereniging tegen de Kwakzalverij doen deze namen alarmbellen rinkelen, en wij vragen dan ook aan Boerhaave Nascholing hoe wij als geïnteresseerde toeschouwers de samenwerking (?) tussen het LUMC en de Boerhaave Commissie (wetenschap) enerzijds en de stichting Voeding Leeft (kwakzalverij) moeten zien.”

Cursusorganisator Boerhaave Nascholing ontdeed zich overigens eerder van kwakzalvers. Eind november 2014 zag Boerhaave Nascholing af van de organisatie van het congres Physical and Biological Correlates in Alternative Healing Modalities van de Society for Scientific Exploration (SSE), een uitermate vage club met allerlei onwetenschappelijke kwakzalverideeën. Het congres ging vervolgens niet door.

Re: Discussie over vitamine D

Geplaatst: 13 sep 2020, 14:31
door laura
The Role of Vitamin D in Thyroid Diseases
Dohee Kim


The main role of vitamin D is regulating bone metabolism and calcium and phosphorus homeostasis. Over the past few decades, the importance of vitamin D in non-skeletal actions has been studied, including the role of vitamin D in autoimmune diseases, metabolic syndromes, cardiovascular disease, cancers, and all-cause mortality. Recent evidence has demonstrated an association between low vitamin D status and autoimmune thyroid diseases such as Hashimoto’s thyroiditis and Graves’ disease, and impaired vitamin D signaling has been reported in thyroid cancers. This review will focus on recent data on the possible role of vitamin D in thyroid diseases, including autoimmune thyroid diseases and thyroid cancers.

Limitations in the Study of Vitamin D

Although many studies have suggested an association of low vitamin D status with AITD and thyroid cancer, epidemiological studies simply show correlative relationships which cannot be used to determine cause and effect [3,72]. Low vitamin D status may be not the cause but rather a consequence of the disease [41,84]. The low vitamin D levels of patients with thyroid diseases can be explained by low vitamin D intake, malabsorption, lack of sun exposure, or reduced outdoor activity [21,29,72,84,85].

In addition, it is likely that good vitamin D status represents a general marker of good health. A young individual with a normal body weight and a healthy lifestyle, including good dietary and exercise habits, is more likely to not only have higher 25(OH)D levels, but also a lower risk of cancer or chronic illness. Therefore, it is difficult to separate the effects of these characteristics from those that may be attributed to 25(OH)D levels [55,76,86].

Similarly, low vitamin D status may be the result of chronic illness, which prevents outdoor activities and sun exposure. Vitamin D is rarely ingested in isolation; therefore, additional nutrients that are co-ingested with vitamin D may have independent or synergistic effects [86]. Additionally, because serum vitamin D levels were measured only once in almost all observational studies, the values obtained might not be representative [70,72,86].

The controversial and varying results of studies are partly due to inter-assay and inter-laboratory variability in the measurements of 25(OH)D, seasonal variations in blood sampling of 25(OH)D, and the different cut-off levels used to define vitamin D deficiency or insufficiency. In addition, the conflicting results could be explained by limitations in study design, such as cross-sectional studies with a small number of subjects, and therefore, the potential for selection bias, as well as the heterogeneity of the study population and the diverse methods used for the diagnosis of AITD, HT, GD, or thyroid cancer [11,29,41,72].


The pleiotropic roles of vitamin D have been recognized through preclinical and observational studies which have suggested a beneficial role of vitamin D in the management of thyroid disease. However, only an ambiguous causal relationship and few interventional studies have been reported to date, so the preventive and therapeutic potential of vitamin D or its analog in thyroid diseases remains debated.

Ongoing and future long-term, randomized controlled trials are required to determine whether individuals with low 25(OH)D levels are at increased risk of developing AITD and thyroid cancer, and to provide insight into the efficacy and safety of vitamin D as a therapeutic tool for these thyroid diseases.