A new study research review by the Health & Food Supplements Information Service (HSIS) has concluded that preventing Vitamin D deficiency can only be achieved through supplementation.
Vitamin D has been a hot topic in recent times and is now also the subject of a new research review titled Vitamin D: The Challenge of Bridging the Gap and the Rationale for Supplementation, published in The Food and Nutrition Journal. The new research review’s authors have shone a light on the mounting evidence pointing to the importance of the sunshine nutrient for our health and wellbeing.
They have also found worrying gaps in the UK’s vitamin D levels, pointing to research showing that amongst 210,502 patients who had a vitamin D test, one-third were deficient (with deficiency identified as a blood level below 30 nmol/litre).
“Closing the gap between vitamin D intakes and recommendations is imperative to prevent deficiency and maintain bone and muscle health, particularly to prevent nutritional rickets and osteomalacia,” says co-author of the new research review and Health & Food Supplements Information Service (HSIS) nutritionist Dr Pamela Mason.
Amid the evidence, the researchers looked at the latest government findings derived from the National Diet and Nutrition Survey (NDNS) data, which reveal that one in five people in the UK is deficient in vitamin D, including:
- 10% of children aged 4-10 years
- 26% of 11–18-year-olds
- 17% of adults aged 19-64 years
- 13% of adults 65+ years
HSIS GP Dr Nisa Aslam, also a study co-author, adds, “It is crucial to prevent deficiency and ensure that 25(OH)D levels (believed to be the best indicator of vitamin D supply to the body) are at least 25 nmol/litre, and possibly even 50 nmol/litre. This can be achieved reliably only by vitamin D supplementation across the population.”
The UK recommends a dose of 10 mcg daily to achieve a serum concentration of 25(OH)D of at least 25 nmol/litre, but in Europe and the US, where the target level of 25(OH)D is more than 50 nmol/litre, data suggest that 10 mcg daily of vitamin D would allow only approximately 50% of the UK population to achieve the European target.
In fact, as HSIS GP Dr Nisa Aslam points out, “We’d need to take 25 mcg of vitamin D daily to achieve the European target level of more than 50 nmol/litre in 97.5% of the UK population.”
Why the gap matters
“Vitamin D is essential for calcium absorption and bone mineralisation, which is positively associated with bone mineral density,” says Dr. Pamela Mason, adding, “Good bone health is essential for consolidating bone mass in adulthood and reducing the risk of osteoporosis in later life.”
Many of the vitamin D guidelines globally (e.g., the UK, wider Europe, Australia and New Zealand, Canada and the US) are based on vitamin D requirements for bone health (sometimes with additional calcium). “This makes sense when you consider that nutritional rickets and osteomalacia represent the most serious health issues associated with vitamin D deficiency,” says GP Dr Nisa Aslam.
Low vitamin D status (less than 50 nmol/litre) also speeds up bone turnover, bone loss and osteoporotic fracture (De Martinis et al, 2021).
Besides our bones, not getting enough vitamin D can negatively impact our:
- Immune function
- Susceptibility to autoimmune conditions such as type 1 diabetes, systemic lupus erythematosus (SLE) and rheumatoid arthritis
- Gut microbiota
- Respiratory system
- Susceptibility to cardiometabolic disease
Conversely, research on the impact of vitamin D supplementation on extra-skeletal functions such as gut, cardiometabolic and respiratory health has generated positive findings.
The sunshine nutrient
A proportion of the vitamin D we need comes from sun exposure. However, as HSIS GP Dr Nisa Aslam explains, “Sun exposure is also the cause of sunburn and a risk for skin cancer. Seasons, time of day, length of day, cloud cover, air pollution, skin melanin content, and sunscreen are among the factors that affect UV radiation exposure and vitamin D skin synthesis.”
She adds, “Sunscreen appears to block vitamin D synthesis, but people usually do not apply sufficient amounts of sunscreen, cover all sun-exposed skin, or reapply sunscreen regularly, so some synthesis will occur, but there has been little agreement on how much.”
There are also other factors to take into account; as HSIS nutritionist Dr Pamela Mason explains, “Research shows that South Asians may need 25 minutes daily of skin exposure, compared with 9 minutes for white-skinned people, to achieve the target serum concentration for vitamin D. Older people, too, are also less able to produce vitamin D from sunlight. So, the practicalities of obtaining enough vitamin D through skin exposure to sunlight are therefore unknown.”
How to bridge the gap
Achieving the UK-recommended daily intake of 10 mcg of vitamin D, which aims to achieve a serum vitamin D level of more than 25 nmol/litre to avoid deficiency from food alone, is highly challenging.
As HSIS nutritionist Dr. Pamela Mason explains, “Very few foods contain vitamin D and oily fish, such as salmon and mackerel, would need to be consumed several times a week if not daily to meet the daily 10 mcg recommendation. This isn’t acceptable to everyone, and only a few foods, such as some cereals and dairy alternatives, are fortified. Supplementation would therefore appear to be the best way to achieve recommended 25(OH)D levels.”
“Encouraging the whole UK population to take the 10-mcg recommended daily dose is important. This dose would allow us to achieve 25(OH)D levels of 25 nmol/litre. However, it’s important to note that this dose would not allow us to achieve the higher serum levels recommended in some other countries,” says HSIS GP Dr Nisa Aslam.
She added, “Despite the lack of international consensus on intakes and adequacy, getting the whole UK population to take the government-recommended 10 mcg daily supplement would reduce the risk of deficiency considerably, and this is why people need to take a multivitamin and multimineral including vitamin D or a vitamin D supplement, daily and all year round.”
Dr. Pamela Mason concludes, “Vitamin D is cost-effective and easy to take. Additionally, supplementation offers potential cost savings to the NHS. Healthcare professionals are in a position to routinely advise patients to take a 10-mcg daily supplement and to increase their intake of vitamin D-containing foods. Advice needs also to be reinforced through care homes, local parenting and community groups and via faith groups.”
For more information, see www.hsis.org.
-  Mason P, Aslam N, Jenkins G, Vitamin D: The challenge of bridging the gap and the rationale for supplementation; ahead of publication: The Food and Nutrition Journal
-  Crowe et al., 2019
-  NDNS years 2016-2019
-  Johnson & Thacher 2023
-  Lanham-new et al 2022
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