Low levels of vitamin D in UK 'extremely concerning', warns the British Nutrition Foundation

21-Nov-2019 - Last updated on 21-Nov-2019 at 15:23 GMT

The BNF's annual lecture calls for greater focus on vitamin D deficiency in younger healthy populations.

Young people in the UK are at increased of risk of diabetes, osteoporosis and osteomalacia – the adult form of rickets – owing to lack of vitamin D in their diet, with South Asians most vulnerable.

Professor Susan Lanham-New, Head of the Nutritional Sciences Department at the University of Surrey, told the British Nutrition Foundation’s (BNF) Annual Lecture 2019: “There is a real need to promote more awareness of vitamin D deficiency across younger populations within the UK. It is established that vitamin D is beneficial for bone health and our studies demonstrate the importance of vitamin D for athletic performance within UK university students too. Good bone health ensures the consolidation of bone mass during adulthood and helps to prevent osteoporosis in later life – more attention needs to be placed on the importance of this.”

University of Surrey research has also shown extensive vitamin D deficiency in over 8,000 South Asians living in the UK.

“Such low levels of vitamin D in this population group is extremely concerning. Due to darker skin pigmentation and lower sun exposure to the skin due to differing lifestyle habits and cultural dress style, this population is particularly susceptible to vitamin D deficiency, and this can lead to osteomalacia – the adult form of rickets,” Lanham-New said.

“This disease presents itself through extensive bone pain, muscle ache and tiredness, and also presents a potential increased risk of diabetes. As such, ensuring an adequate intake of vitamin D through diet or supplements is essential.”

Vitamin D is important in bone health as it helps regulate the amount of calcium and phosphate in the body. However, it is estimated that around one in five people in the UK have low levels of Vitamin D. The body creates vitamin D from direct sunlight on the skin when outdoors but, between October and early March, the UK population will simply not get enough vitamin D from sunlight due the strength of the sun being of insufficient UV wavelength, and it is very difficult to get enough vitamin D to compensate for this from foods that are unfortified.

The UK government recommends that all adults and children over five should consider taking a daily supplement containing 10 micrograms of vitamin D during the autumn and winter,

D3 more effective than D2 in fortified food

Lanham-New also highlighted the importance of the different forms of vitamin D that can be used in supplements or in fortified foods.

Historically, it has been suggested that there is no difference between vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol) in their effectiveness in improving vitamin D status. However, recent research led by Dr Laura Tripkovic and Dr Louise Durant (nee Wilson) from the Department of Nutritional Sciences, University of Surrey, has investigated whether vitamin D2 or vitamin D3 added to juice or food, at a relatively low dose of 15 mg/d, was effective in increasing serum total 25(OH)D, and compared the respective efficacy of these two forms of vitamin D in South Asian and white European women over the winter months.

Although both vitamin D2 and vitamin D3 increased 25(OH)D status and prevented the decline in 25(OH)D status during the wintertime, the results showed that at a low, but relevant, dose of 15 mg/d, vitamin D3 was much more efficacious than vitamin D2 at increasing total 25(OH)D.

“Our novel work on differences in vitamin D2 and vitamin D3 has highlighted some key issues with respect to the use of vitamin D2 fortification. This study is larger and more comprehensive than previous trials and backs up theories suggesting that, for the most effective supplementation, foods and drinks should be fortified with vitamin D3. This finding is particularly key for vegetarians and vegans, since vitamin D3 is from an animal source. We are now working on a systems biology approach to vitamin D and we have some further exciting data in preparation on vitamin D2 and vitamin D3.”

Professor Susan Lanham-New’s research focuses on the area of nutrition and bone health, and also incorporates work on acid-base homeostasis and bone health. While this has been an area of media controversy, with unfounded suggestions that following an ‘alkaline diet’ can benefit conditions such as cancer and arthritis, there are real mechanisms by which dietary acidity and alkalinity can affect bone health. Research suggests that certain bone cells appear to be sensitive to acidity, resulting in increased levels of bone resorption – the breakdown of bone materials and loss of minerals, potentially resulting in reductions in bone mass.

Lanham-New explained: “Studies looking at the use of alkaline-based potassium supplements, (for example, potassium bicarbonate/potassium citrate), which can increase dietary alkalinity, have also shown significant reductions in bone loss. Hence, dietary alkali supplementation or increased fruit and vegetable intake may be a beneficial strategy for improving bone health in the population, particularly for women going through menopause when bone resorption is particularly high due to the low oestrogen levels.”

New research by University of Surrey analysed the effects of vitamin D status on athletic performance in University-level athletes, and revealed that the results indicate that insufficient vitamin D negatively impacts predictors of jump height and aerobic fitness in these populations.

Therefore, as well being related to poor musculoskeletal health, which means athletes are more susceptible to injuries like stress fractures, vitamin D deficiency may also affect athletic performance.