Vitamin D deficiency has been linked to increased risk of asthma, cancer and chronic pain, among other conditions. Now, a new study led by researchers from the University of Georgia associates low vitamin D levels with greater risk of seasonal affective disorder (SAD).

SAD is a form of depression that occurs during the winter months. Symptoms include feeling sad or anxious, fatigue, concentration problems, irritability and feelings of guilt and hopelessness. The research team—led by Alan Stewart of the College of Education at the University of Georgia—published their findings in the journal Medical Hypotheses.1

This is the latest in a raft of studies linking health conditions to vitamin D deficiency. Vitamin D is important for keeping bones and teeth healthy. A lack of the vitamin can lead to deformities such as rickets in children, and a condition known as osteomalacia in adults, which causes pain and tenderness. In England, around a fifth of adults and a sixth of children—approximately 10 million people—may have low vitamin D status.2 This is partly because the main source for vitamin D is from natural sunlight, and for six months of the year—from mid-October to the beginning of April—there is no sunlight at the correct wavelength for skin to create vitamin D.

As a result NICE has called for wider availability of low-cost supplements that could help prevent health problems in millions of people at risk of vitamin D deficiency.2 It recommends increasing access to vitamin D supplements, and raising awareness of the health problems associated with it, to address those who may be at risk. While people from at risk groups are advised to take a vitamin supplements, they do not always receive the information and support they need. For example, there is low uptake of the Healthy Start scheme, which provides free vitamin D supplements to pregnant and breastfeeding women.

Certain groups of people in the UK are also more likely to have a lack of vitamin D. These include pregnant women, children and older adults. People with darker skin are also at risk of having low vitamin D levels.

The guideline aims to increase the use of vitamin D supplements to prevent deficiency among those most at risk and it recommends that access to vitamin D supplements containing the recommended dose should be increased.2

Professor Mike Kelly, Director of the NICE Centre for Public Health, said: “Around 10 million people in England may have low vitamin D status and so could be at risk of health problems—and they may not know it. People with darker skin are particularly at risk— during winter months nearly 75% of adults from Asian or African and Caribbean backgrounds may have low vitamin D levels. People who are over 65 years old are another group at risk of having low vitamin D levels, and so are also at risk of conditions like osteomalacia—soft bones. NICE recommends making low cost vitamin D supplements widely available to people at risk of deficiency.” 

NICE say that local authorities should also ensure supplements containing the recommended dose of vitamin D are available at all at-risk groups, in settings such as pharmacies, children’s centres and GP reception areas. In addition, they should consider providing free supplements for at-risk groups, and encourage pharmacies and other outlets selling supplements to stock the lowest cost vitamin D supplements and promote them to those at risk. Local public health teams, health and social care practitioners and voluntary and community groups working with at-risk groups should also increase people’s awareness of the importance of vitamin D for good health sources of vitamin D in the UK (from safe sun exposure, supplements and limited dietary sources).