Low levels of Vitamin D linked to muscle fat, decreased strength in young
There’s an epidemic in progress, and it has nothing to do with the flu. A ground-breaking study published in the March 2010 Journal of Clinical Endocrinology and Metabolism found an astonishing 59 per cent of study subjects had too little Vitamin D in their blood. Nearly a quarter of the group had serious deficiencies (less than 20 ng/ml) of this important vitamin. Since Vitamin D insufficiency is linked to increased body fat, decreased muscle strength and a range of disorders, this is a serious health issue.
“Vitamin D insufficiency is a risk factor for other diseases,” explains principal investigator, Dr. Richard Kremer, co-director of the Musculoskeletal Axis of the Research Institute of the MUHC. “Because it is linked to increased body fat, it may affect many different parts of the body. Abnormal levels of Vitamin D are associated with a whole spectrum of diseases, including cancer, osteoporosis and diabetes, as well as cardiovascular and autoimmune disorders.”
The study by Dr. Kremer and co-investigator Dr. Vincente Gilsanz, head of musculoskeletal imaging at the Children’s Hospital Los Angeles of the University of Southern California, is the first to show a clear link between Vitamin D levels and the accumulation of fat in muscle tissue – a factor in muscle strength and overall health. Scientists have known for years that Vitamin D is essential for muscle strength. Studies in the elderly have showed bedridden patients quickly gain strength when given Vitamin D.
The study results are especially surprising, because study subjects – all healthy young women living in California – could logically be expected to benefit from good diet, outdoor activities and ample exposure to sunshine – the trigger that causes the body to produce Vitamin D.
“We are not yet sure what is causing Vitamin D insufficiency in this group,” says Dr. Kremer who is also Professor of Medicine at McGill University. High levels of Vitamin D could help reduce body fat. Or, fat tissues might absorb or retain Vitamin D, so that people with more fat are likely to also be Vitamin D deficient.”
The results extend those of an earlier study by Dr. Kremer and Dr. Gilsanz, which linked low levels of Vitamin D to increased visceral fat in a young population. “In the present study, we found an inverse relationship between Vitamin D and muscle fat,” Dr. Kremer says. “The lower the levels of Vitamin D the more fat in subjects’ muscles.”
Vitamin D Tied to Muscle Power in Adolescent Girls
Vitamin D is significantly associated with muscle power and force in adolescent girls, according to a new study in The Endocrine Society’s Journal of Clinical Endocrinology & Metabolism (JCEM). The article “Vitamin D Status and Muscle Function in Post-Menarchal Adolescent Girls,” appeared in the February 2009 issue.
Although vitamin D is naturally produced in the body through exposure to direct sunlight, vitamin D deficiency has become widely common in the United States. Vitamin D deficiency has been shown to have a significant negative impact on muscle and bone health, and can lead to conditions including osteoporosis and rickets.
“We know vitamin D deficiency can weaken the muscular and skeletal systems, but until now, little was known about the relationship of vitamin D with muscle power and force,” said Dr. Kate Ward, Ph.D., of the University of Manchester in the U.K., and lead author of the study. “Our study found that vitamin D is positively related to muscle power, force, velocity and jump height in adolescent girls.”
For this study, researchers followed 99 adolescent girls between the ages of 12 and 14 years. Dr. Ward and her colleagues took blood samples to measure the girls’ serum levels of vitamin D. Many of these girls were found to have low levels of vitamin D despite not presenting any symptoms.
Researchers used a novel outcome measure called jumping mechanography to measure muscle power and force. Jumping mechanography derives power and force measurements from a subject’s performance in a series of jumping activities. Dr. Ward says this method of testing is ideal as the muscles required to jump are those most often affected in subjects with vitamin D deficiency. Girls without vitamin D deficiency performed significantly better in these tests.
“Vitamin D affects the various ways muscles work and we’ve seen from this study that there may be no visible symptoms of vitamin D deficiency,” said Dr. Ward. “Further studies are needed to address this problem and determine the necessary levels of vitamin D for a healthy muscle system.”
Vitamin D proven to boost energy -- from within the cells
Vitamin D is vital for making our muscles work efficiently and boosting energy levels, new research from Newcastle University has shown.
A study led by Dr Akash Sinha has shown that muscle function improves with Vitamin D supplements which are thought to enhance the activity of the mitochondria, the batteries of the cell.
A hormone normally produced in the skin using energy from sunlight, Vitamin D can also be found in a few foods – including fish, fish liver oils, egg yolks and fortified cereals but it can also be effectively boosted with Vitamin D supplements.
It is thought around 60% of people in the UK are vitamin D deficient, with children under five, people with dark skin and the elderly being particularly vulnerable. While it has a well-established association with helping in bone formation and a deficiency can lead to rickets, its role in other health issues is just emerging.
The researchers used non-invasive magnetic resonance scans to measure the response to exercise in 12 patients with severe deficiency before and after treatment with vitamin D.
Lead author Dr Akash Sinha who also works within the Newcastle upon Tyne Hospitals NHS Foundation Trust said: "The scans provided a unique window into what is really going on in the muscle as it works.
"Examining this small group of patients with vitamin D deficiency who experienced symptoms of muscle fatigue, we found that those with very low vitamin D levels improved their muscle efficiency significantly when their vitamin D levels were improved."
Alongside poor bone health, muscle fatigue is a common symptom in vitamin D deficient patients. This fatigue could be due to reduced efficiency of the mitochondria: the 'power stations' within each cell of the body.
Mitochondria use glucose and oxygen to make energy in a form that can be used to run the cell - an energy-rich molecule called ATP. Muscle cells need large amounts of ATP for movement and they use phosphocreatine as a ready and available energy source to make ATP. The mitochondria also replenish this phosphocreatine store after muscle contraction and measuring the time taken to replenish these stores is a measure of mitochondrial efficiency: better mitochondrial function is associated with shorter phosphocreatine recovery times.
The team found that these recovery rates significantly improved after the patients took a fixed dose of oral vitamin D for 10-12 weeks. The average phosphocreatine recovery half time decreased from 34.4 sec to 27.8 sec. All patients reported an improvement in symptoms of fatigue after having taken the supplements. In a parallel study, the group demonstrated that low Vitamin D levels were associated with reduced mitochondrial function.
Dr Sinha added: "We have proved for the first time a link between vitamin D and mitochondria function.
"Of the patients I see, around 60% are vitamin D deficient and most people living north of Manchester will struggle to process enough vitamin D from sunlight alone, particularly during winter and spring. So a simple vitamin D tablet could help boost your energy levels – from within the cells."