The Sunshine Vitamin
Why Vitamin D is Essential for Your Health
Vitamin D, often referred to as the "sunshine vitamin," is unique because your body can produce it naturally when exposed to sunlight. When ultraviolet B (UVB) rays (wavelength 290–320 nm) reach the skin, they activate keratinocytes to convert 7-dehydrocholesterol into cholecalciferol (D3). This D3 is transformed in the liver into calcidiol and then in the kidneys into calcitriol—the active form of vitamin D. Discovered in 1971 by Hector DeLuca and colleagues, calcitriol functions as a hormone that regulates various critical processes, including bone health and immune responses.
The Dual Role of Vitamin D in Bone and Immune Health
Bone Health
Vitamin D is essential for calcium, phosphate, and magnesium regulation, crucial for strong bones and muscles. Without it, the following conditions can arise:
Rickets in Children: This condition leads to stunted growth, bowed legs, knock knees, bone pain, and developmental delays. Severe cases can result in seizures, dental abnormalities, and even heart complications.
Osteomalacia in Adults: Poor bone mineralisation leads to weak bones, aches, and a higher fracture risk. Affected individuals may also experience odontomalacia (softening of teeth) and muscle pain.
Osteoporosis: Although primarily linked to long-term calcium insufficiency, vitamin D deficiency can exacerbate this condition, leading to brittle, fragile bones. Postmenopausal women are especially vulnerable due to declining oestrogen levels.
Immune Health
Vitamin D influences both innate and adaptive immune responses, helping the body fight infections and control inflammation. Key benefits include:
Reduced risk of respiratory infections and a potential reduction in severe complications like cytokine storms.
Lower incidence of autoimmune diseases such as multiple sclerosis, rheumatoid arthritis, and type 1 diabetes.
Vitamin D: More Than a Nutrient
Despite being called a vitamin, vitamin D behaves more like a hormone. Unlike traditional vitamins, it is synthesised in the body and stored in fat tissue, particularly in subcutaneous fat. However, this fat-solubility can lead to unique challenges:
Obesity and Vitamin D Deficiency: Excess fat can trap vitamin D, rendering it less available for immediate use, a phenomenon described as “famine in a sea of plenty.”
Low Body Fat and Readily Available Vitamin D: Individuals with minimal body fat may have more circulating vitamin D but reduced stores for long-term use.
Sources and Synthesis of Vitamin D
The main forms of vitamin D are D2 (ergocalciferol) and D3 (cholecalciferol):
Natural Sources: D3 is found in animal products like oily fish (e.g., salmon) and cod liver oil. D2 is present in sun-exposed mushrooms, such as portobello mushrooms.
Sunlight: Moderate exposure to midday sun on the face and arms for about 20 minutes several times a week is sufficient for most people during the summer. However, sunlight through glass, darker skin tones, sunscreen use, and ageing can reduce vitamin D production.
Vitamin D in the UK: Challenges and Recommendations
In the UK, adequate sunlight for vitamin D synthesis is limited to the summer months. During the winter, most people need dietary sources or supplements to maintain healthy levels. Certain groups are more vulnerable to deficiency, including:
Individuals with darker skin tones.
Older adults.
People with limited outdoor activity or consistent sunscreen use.
Populations at higher latitudes.
Those with conditions like inflammatory bowel disease (IBD), coeliac disease, or chronic kidney disease (CKD).
Exclusive breastfeeding without supplementation can also lead to vitamin D deficiency in infants.
Signs of Low Vitamin D You Should Not Ignore
If you are suffering from the following symptoms then you may be vitamin D deficient: Persistent fatigue, muscle weakness, and aching bones. Frequent illnesses, slow wound healing, and mood changes like depression or anxiety are also common. Hair loss, brittle bones, and dental problems may develop over time. Some individuals may experience muscle cramps, twitches, or sleep disturbances.
Groups at higher risk include those with darker skin tones, older adults, individuals with limited sun exposure or certain health conditions and everyone living between “Land’s End” and “John o’ Groats”!
Maintaining Optimal Vitamin D Levels
For many, a combination of sunlight, dietary sources, and supplements ensures sufficient vitamin D levels throughout the year. Regular blood tests can help monitor and manage deficiencies, especially for at-risk individuals.
At London Harley Street Practice, we offer comprehensive assessments and guidance on maintaining optimal vitamin D levels tailored to your individual needs. Book a consultation today and take the first step towards improved health and well-being.
You can even book your vitamin D blood test on line, read more here how to do it. Book your test today.
Dr S Cumbers
Copyright London Harley Street Practice