There is no question that suitable vitamin D levels are important to the health of us all, and at all stages of our life; and this includes from in the womb. There is also no question that many groups of the UK population have low vitamin D status. The UK Government currently have a range of recommendations in respect of ensuring certain population groups get enough vitamin D.
Vitamin D has a number of permitted health claims from EFSA (The European Food Safety Authority) which are only granted to nutrients following a rigorous evaluation process. Vitamin D has more recently become the focus of a great deal of worldwide research regarding its potential health benefit for a range of ailments. This includes studies on vitamin D levels and cognitive health (including Alzheimer’s and Dementia), cardiovascular health, MS, allergies (including asthma) and breast cancer.
The role of vitamin D is indeed attracting a good deal of media attention with some health professionals and researchers suggesting that deficiency has a role in many chronic diseases. It would appear that vitamin D deficiency is widespread worldwide.
Vitamin D – Permitted Health Claims
These are the current permitted EFSA health claims for Vitamin D:
- Vitamin D contributes to the normal absorption /utilisation of calcium and phosphorus
- Vitamin D contributes to normal blood calcium levels
- Vitamin D contributes to the maintenance of normal bones and teeth
- Vitamin D contributes to the maintenance of normal muscle function
- Vitamin D contributes to the normal function of the immune system
- Vitamin D has a role in the process of cell division
- Vitamin D is needed for normal growth and development of bone in children
The ‘Sunshine Vitamin’ & Vitamin D in Foods
Vitamin D is commonly known as the ‘Sunshine Vitamin’ as sunlight is necessary for the synthesis of vitamin D and those lacking in sunlight are at high risk of deficiency. We can’t stress this point enough as vitamin D is not found in abundance naturally in foods. The best sources are oily fish followed by milk and eggs.
Many people eat little fish or dairy products and even if you consume a lot this may not give you sufficient vitamin D intake. Intake of vitamin D is needed throughout the year and getting some sunshine in the summer will not provide the amounts needed all-year-round. Hence problems with vitamin D deficiency in the UK and many parts of Europe.
Naturally we all have to be mindful about avoiding too much sunshine as there are serious long-term skin cancer health risks associated. Sunblocks will affect the synthesis of vitamin D in our body.
Salmon, mackerel, tuna, sardines, milk, eggs, beef, liver and Swiss cheese are examples of foods that naturally contain Vitamin D. More recently some makes of processed foods are fortified with added vitamin D.
Vitamin D – UK Government advice on supplements for at risk groups
The Chief Medical Officers for the United Kingdom raises awareness of the risk of vitamin D deficiency amongst certain groups and there are currently recommendations in place for a number of these to take vitamin D supplements:
- All pregnant and breastfeeding women
- Infants and young children under 5 years of age
- Older people aged 65 years and over
- People who have low or no exposure to the sun
For full details and clarification on this advice follow the link below. This also includes advice for people who have darker skin (who are unable to naturally ‘make’ as much vitamin D).
Vitamin D – Normal growth and development of bone in children
Vitamin D is important in pregnancy to support the mother and in particular to provide the foetus and subsequent baby with suitable levels of the vitamin. Vitamin D is needed for normal growth and development of bone in children. For children one consequence of not having enough vitamin D is it can cause their bones to soften and can lead to rickets (a bone development disease in children).
In December 2012 the Royal College of Paediatrics and Child Health expressed ongoing concerns about vitamin D deficiency in UK children leading to an increased range of ailments including a worrying rise in rickets cases. Breast feeding women who are themselves deficient in Vitamin D will pass little of the vitamin in their breast milk.
In evaluating and granting the health claim that ‘Vitamin D contributes to the normal growth and development of bone in children’ the EFSA Scientific Committee provide a summary which includes the following text:
“Reports from authoritative bodies and reviews show that there is good consensus on the role of vitamin D in growth and development of bone. Adequate status for vitamin D is required for efficient calcium absorption and for the maintenance of normal blood levels of calcium and phosphate that are needed for the normal mineralisation of bone.
The serum level of calcidiol (25(OH)D) is a good marker of status for vitamin D. Synthesis of vitamin D in the skin by the action of sunlight is insufficient to meet requirements in European countries, especially during winter months when there is little sunlight exposure.
Adequate intake of vitamin D throughout childhood and adolescence is needed to achieve a vitamin D status that is sufficient for normal bone mineralisation, and sub-optimal vitamin D status has been shown to reduce bone mineral accretion in children and adolescents. Recommended intakes of vitamin D for normal growth and development of bone have been established for children and adolescents by several expert committees. Sub-optimal vitamin D status has been reported in sub-groups of children and adolescents in a number of European countries, particularly in winter months, indicative of inadequate vitamin D intake”.
The link to the full EFSA summary:
EFSA: Opinion of the Scientific Committee/Scientific Panel
Vitamin D – The normal absorption & utilisation of calcium and phosphorus
‘Vitamin D contributes to the normal absorption & utilisation of calcium and phosphorus’ is a permitted EFSA health claim and noted in their summary above. The action of vitamin D in supporting the two minerals underlines the importance of both vitamin D levels for bone health and it is also a good example of nutritional ‘synergy’. In this case calcium is recognised as being important for bone health yet with inadequate intake of vitamin D (in this example) the positive effect of the calcium will be more limited.
The NHS provide a helpful and simple description of the importance of this vitamin D function. They also comment on its relevance in helping to prevent rickets in children:
“Vitamin D has several important roles, for example, it helps control the amount of calcium and phosphate in your body, which are needed to keep your bones and teeth healthy.
Having too little vitamin D (a deficiency) can damage the way your body absorbs calcium and phosphorus. In children, this can lead to rickets, a condition that can cause bone deformities, such as bowed legs. In adults, vitamin D deficiency can cause osteomalacia (weak bones), which can make bones painful and tender.”
Link to the web page and full description: NHS: What does vitamin D do
For those who would like a more technical overview of this function of vitamin D the BMJ provide the following text which is part of a wider description of vitamin D deficiency and this includes some excellent diagrams:
Skeletal action of vitamin D: “Children: vitamin D deficiency is the most common cause of rickets. Vitamin D deficiency prevents efficient absorption of dietary calcium and phosphorus. The poor absorption of calcium causes a decrease in serum ionised calcium, resulting in secondary hyperparathyroidism. Parathyroid hormone (PTH) decreases phosphorus reabsorption in the kidney, causing loss of phosphorus into the urine. Therefore, the serum calcium is usually normal in a vitamin D-deficient infant or child. However, the serum phosphorus level is low or low-normal, and therefore there is an inadequate calcium-phosphorus product, causing a defect in the mineralisation of the collagen matrix.”
Link to the relevant web page and full description: BMJ: Vitamin D deficiency
The function of vitamin D and calcium metabolism is also relevant for older people (typically aged 50 plus), when there is an increased and common risk of osteoporosis (often termed ‘thinning’ or ‘brittle bones’). There is a well-established link between vitamin D deficiency and osteoporosis and this is most associated with the negative effect on calcium metabolism.
As previously noted, for the uptake of calcium we require vitamin D. However vitamin D status declines with age, with a decreased ability to synthesise vitamin D from sunlight. This scenario may be further exacerbated because of elected avoidance of sun exposure. The use of sun screens also reduces the potential for synthesis of vitamin D from the sun.
Vitamin D also has the permitted claim of ‘contributes to the maintenance of normal muscle function’. This has relevance to all age groups and none more so than those at risk of osteoporosis. A study reported in the ‘Journal of Bone and Mineral Research’ looked at the specific receptors for vitamin D in human muscle tissue, and studies showed increased muscle strength and reduced falls in the elderly. A double-blind, randomised controlled
trial was undertaken with 122 elderly women, concluding that: “a single intervention with vitamin D plus calcium over a 3-month period reduced the risk of falling by 49% compared with calcium alone”.
Following on from the observation above on a potential relationship between vitamin D deficiency and falls among the elderly. JABFM (the journal of the American board of family medicine) in their excellent and in-depth review on vitamin D (titled ‘Vitamin D: An Evidence-Based Review’) comment: “Although it is well known that the combination of vitamin D and calcium is necessary to maintain bone density as people age, vitamin D may also be an independent risk factor for falls among the elderly.” They continue:
“Vitamin D status is increasingly recognized as an important factor in fall status among elderly patients. Several trials have demonstrated that vitamin D supplementation decreases the risk of falling. One proposed mechanism is that higher vitamin D levels are associated with improved muscle function.”
Link to the full JABFM article: JABFM: Vitamin D – An Evidence-Based Review
Vitamin D receptors are to be found in skeletal muscle cells and research suggests that people with unwarranted muscle aches, pains and weakness have a significant incidence of low serum vitamin D,
These points all go to underline the importance of vitamin D levels for all, but particularly as we age. Hence the UK Government recommendations for vitamin D supplementation for the over 65’s.
EFSA in their Scientific Opinion on the substantiation of health claims related to vitamin D and normal muscle function commented:
“Muscle weakness is a feature of the clinical syndrome of vitamin D deficiency. Clinical symptoms of vitamin D deficiency myopathy include proximal muscle weakness, diffuse muscle pain, and gait impairments such as waddling way of walking (Schott and Wills, 1976; Ceglia, 2008). The vitamin D receptor is expressed in human muscle tissue, and its activation may promote de novo protein synthesis in muscle (Sorensen et al., 1979). The Panel considers that a cause and effect relationship has been established between the dietary intake of vitamin D and maintenance of normal muscle function.”
The link to the full EFSA summary:
EFSA: Opinion of the Scientific Committee/Scientific Panel
Vitamin D – normal function of the Immune System
Vitamin D has the permitted health claim of ‘contributes to the normal function of the immune system’. Vitamin D is essential to innate immune cell functions and the association between vitamin D depletion and weakened immune function has been researched. Supplementation with vitamin D at doses of up to 10,000 IU have been recommended as a result of such research. We comment on vitamin D dosages and recommendations later.
In 2010 the University of Copenhagen released research on vitamin D and immune defence. This was summarised by science daily as follows:
“Scientists have found that vitamin D is crucial to activating our immune defences and that without sufficient intake of the vitamin – the killer cells of the immune system – T cells – will not be able to react to and fight off serious infections in the body. The research team found that T cells first search for vitamin D in order to activate and if they cannot find enough of it will not complete the activation process.”
Link to the full article:
ScienceDaily: Vitamin D crucial to activating immune defenses
Research into the role of vitamin D deficiency and ‘infectious immune disorders’ and ‘autoimmune diseases’ continues with the role of a lack of vitamin D from sunlight seen by some researchers an important contributory factor. Research has noted the incidence of such diseases related to geographical latitude (e.g. less sunshine).
In our introduction we commented on ongoing research into vitamin D deficiency and MS (Multiple Sclerosis). The UK charity the Multiple Sclerosis Trust provide some interesting reading on the vitamin and this includes the comment that “Studies of the distribution of MS around the world show that it is generally more common the further you are from the equator. This suggests a link between lack of exposure to sunlight, consequent lack of vitamin D production and the development of MS.”
Link to the full article: MS TRUST: Vitamin D
For those who would like a more technical overview of this function of vitamin D – EFSA in their ‘Scientific Opinion’ on the substantiation of health claims related to vitamin D and the normal function of the immune system comments:
“Vitamin D plays a regulatory role in the functioning of the immune system. A vitamin D receptor (VDR) was identified in peripheral mononuclear cells and in both T-helper 1 (Th1) and T-helper 2 (Th2) cells. 1,25(OH)2D reduces the inflammatory response of Th1 cells, suppresses antigen presentation by dendritic cells, suppresses proliferation and immunoglobulin production and retards the differentiation of B cell precursors into plasma cells, exerting an inhibitory action on the adaptive immune system. 1,25(OH)2D increases expression of cathelicidin (LL-37), an antimicrobial peptide thought to be important for the innate immune system, especially against Mycobacterium tuberculosis (Bikle, 2009; Cantorna et al., 2008; Khazai et al., 2008). The Panel concludes that a cause and effect relationship has been established between the dietary intake of vitamin D and contribution to the normal function of the immune system and healthy inflammatory response.”
The link to the full EFSA summary: EFSA: Opinion of the Scientific Committee/Scientific Panel
Vitamin D and Cardiovascular Disease
The importance of vitamin D in supporting cardiovascular health has been the subject of much research; and studies continue. There are currently no permitted EFSA health claims that support the vitamin in this respect. However research indicates that for blood pressure (for example) vitamin D may help by relaxing vascular smooth muscle tissue.
JABFM (the journal of the American board of family medicine) provide an excellent externally peer reviewed study on vitamin D titled ‘Vitamin D: An Evidence-Based Review’ and an extract on vitamin D and cardiovascular disease notes:
“Vitamin D receptors are present in vascular smooth muscle, endothelium, and cardiomyocytes and may have an impact on cardiovascular disease. Observational studies have shown a relationship between low vitamin D levels and blood pressure, coronary artery calcification, and existing cardiovascular disease. A large cohort study that included more than 1700 participants from the Framingham offspring study looked at vitamin D levels and incident cardiovascular events.8 During a period of 5 years, participants who had 25-OH D levels of
Link to the full JABFM article: JABFM: Vitamin D – An Evidence-Based Review
Vitamin D3 and RDA
Vitamin D3 is the most bioavailable form of this nutrient and far preferable to Vitamin D2 to supplement with. There is ongoing debate on what levels of Vitamin D to supplement with – recent studies suggest that significantly higher levels than the current European RDA (Recommended Daily Allowance) are optimally beneficial. Vitamin D3 is also termed ‘cholecalciferol’
Where you wish to take a multivitamin and mineral that includes Vitamin D3 it is always important to select such a multi-formula with a nutrient content tailored for your age, gender, pre-existing medical conditions, or specifically for children where appropriate. If you are considering taking a vitamin D3 supplement and a multivitamin make sure that you assess the total combined dosage of the vitamin that you will be taking.
‘Health of the Nation’ 2014 survey & vitamin D
Whilst composing this article the HFMA (Health Food Manufacturers’ Association) released their ‘Health of the Nation’ 2014 survey results; comprising feedback from more than 10,000 adults who took part in the survey. It was a timely reminder about the unfortunate lack of public awareness of the importance of good vitamin D levels. The survey was widely reported on in the mainstream media including TV, press and radio. The ‘key findings per interest area for vitamin D’ were:
- With the number of food sources for vitamin D being extremely limited, only 16% eat and consider fresh fish as contributing towards their vitamin D intake and only 11% consider breakfast cereals as a source
- Conversely, more people (46%) mistakenly believe they are getting vitamin D from vegetables
- Almost 40% (39%) do not know which vulnerable groups the government advises to take vitamin D supplements
- 27% could not recognise any of the signs of vitamin D deficiency
- To help reduce the loss of bone later in life, only 37% recognised vitamin D as important
- Only half (51%) think it is particularly important to have sufficient intake of vitamin D for bone health in childhood and only 57% think it important for infancy, whilst only a third (33%) believe vitamin D is important for adults aged 80+
- The British Medical Journal (BMJ) reports stating that more than 50% of the adult population have insufficient levels of vitamin D during winter and spring
- Reports have shown that nearly three-quarters of parents and more than half of health professionals are unaware of these current DoH recommendations
- Pilot studies and regional monitoring suggests that vitamin D deficiency is likely to affect at least half the UK’s white population, up to 90% of the multi-ethnic population and a quarter of all children living in Britain. In addition, there has been a four-fold increase in admissions to hospital with rickets in the last 15 years
Link to the HFMA press release: HFMA: Health of the Nation
If you have any questions regarding this article, any of the health topics raised, or any other health matters please do contact me (Amanda) by phone or email at any time.
Amanda Williams, Cytoplan
firstname.lastname@example.org, 01684 310099
A fully referenced article is available on request.