For the next topic in our series about why you should always take your metabolic formula if you’re restricting your diet, we’re going to discuss Vitamin D. In PKU deficiency is common, and following a restricted diet without taking your PKU supplement increases your chances of developing this deficiency.
Vitamin D regulates calcium absorption and homeostasis. That means it’s super important for bone health! It promotes calcium absorption from the gut, enables mineralisation of newly formed osteoid tissue in bone and plays an important role in muscle function (NOS 2013). Over the last decade, evidence has suggested that low serum concentrations of 25-hydroxyvitamin D, 25(OH)D, are associated with a number of non-skeletal disorders including cancer, heart disease, high blood pressure, diabetes, age-related cognitive decline, Parkinson’s disease, multiple sclerosis and arthritis. However, whether low 25(OH)D is the cause or result of ill health is not yet clear (Autier et al. 2014).
UVB sunlight exposure is the main source of Vitamin D, however, synthesis of vitamin D varies during the year with peak levels recorded following the summer months. In the U.K., sunlight is not strong enough to trigger synthesis of vitamin D in the skin from October to March. Therefore, we rely on dietary vitamin D and body stores to maintain a healthy vitamin D status, particularly during the winter.
The UK National Diet and Nutrition Survey 2008–2012 reported approximately 40% of males and females age 11-64 years have Vitamin D levels below the recommended level between January & March and 25% year round. Vitamin D status in post-menopausal women is of interest because of the association of low vitamin D status with increased risk of osteoporosis and fracture.
Treatment is either with capsules (adults) or liquid for children, in severe cases an intramuscular injection may be needed.
Vitamin D deficiency can be prevented. Do you know your Vitamin D status? Ask your GP or metabolic clinic for a blood test to check your levels, and remember to be reviewed regularly at a metabolic clinic even if you’re not on diet.
Spiro, A, and J L Buttriss. “Vitamin D: An Overview of Vitamin D Status and Intake in Europe.” Nutrition Bulletin / Bnf 39.4 (2014): 322–350
NOS (National Osteoporosis Society) 2013. Vitamin D and bone health: a practical clinical guideline for patient management.
Autier P, Boniol M, Pizot C, et al. Vitamin D status and ill health: a systematic review. The Lancet. Diabetes & Endocrinology. 2014;2:76–89