Vitamin D deficiency is linked to poor muscle function after you enter your sixties

As you grow older your skeletal muscle slowly dwindles, you lose muscle strength, and your figure changes. This phenomenon is known as sarcopenia and is one of the main reasons why older people gradually become frail and perhaps even invalid. Both diet and exercise play an important role and according to a new study from Trinity College Dublin, lack of vitamin D also plays a major contribution to the development of poor muscle control in people from 60 years of age and older. It doesn’t make things easier that we are only able to synthesize vitamin D in our skin during the summer period and the ability to do so decreases with age. For that reason, older people should pay careful attention to getting plenty of vitamin D all year round to maintain as much muscle mass as possible and ensure that their muscles function properly.

The ability to maintain proper functioning of skeletal muscle throughout life is vital for healthy ageing and for staying mobile, physically independent, and for lowering your risk of fractures and complications from fall accidents. But the natural loss of muscle mass and muscle strength slowly sets in around the age of 40 and the process starts to speed up in your late sixties and early seventies. Your figure also changes accordingly, making your arms and legs thinner and your bottom flatter. The health authorities explain that exercise and physical activity is the only way to prevent this loss of muscle mass. However, the new study from Trinity College Dublin also suggests that plenty of vitamin D can protect against the loss of muscle and reduced muscle function.

Vitamin D’s importance for muscles throughout life

It is commonly known that vitamin D is important for bones and the immune defense. What most people are not aware of is that vitamin D affects most organs in the body, for instance by activating genes for different cells.
An increasing amount of evidence suggests that vitamin D plays a role in muscle health and strength. This knowledge is highly useful for the many people that suffer from different muscle diseases and sarcopenia. These conditions are particularly problematic for the chronically ill and old people, as it affects their entire musculoskeletal system and impairs their quality of life.
According to the new Irish study that is published in Clinical Interventions in Ageing, there is evidence that having sufficient amounts of vitamin D in your blood may protects against loss of muscle mass and associated diseases. The scientists observed the following:

• Lack of vitamin D is widespread among older people
• Muscle weakness was twice as common among old people that were vitamin D-deficient compared with people who had plenty of vitamin D in their blood
• Impaired muscle function was three times more common in vitamin D-deficient seniors compared with those who had plenty of vitamin D
• More complex analyses revealed that vitamin D deficiency significantly impaired both muscle strength and muscle function
• The study confirmed the benefits of physical activity
• It is commonly known that lack of vitamin D causes bone diseases that should be prevented
• This strategy should also be included in the prevention of musculoskeletal diseases

More vitamin D throughout life – especially for older people

The study results are based on data from 4,157 home-living participants from 60 years and older that were recruited from the larger ELSA study (English Longitudinal Study of Ageing). The participants’ grip strength was measured as this is a useful indicator of reduced muscle strength. The participants were also exposed to the SPPB test (Short Physical Performance Battery) that measures gait speed, chair stand, and balance. SPPB helps assess older peoples’ physical capability and is useful for predicting when they are in need of home assistance or at risk of complicated falls or premature death.
The scientists behind the new study point out that lack of vitamin D increases the risk of poor muscle function in old people, and the study underlines the importance of physical activity.
Maintaining good muscle function throughout life is extremely important but is often overlooked in various healthy ageing awareness campaigns. It is also important to eliminate the widespread vitamin D deficiency among older people.
Both physical activity and lack of vitamin D are factors that can be addressed. In Finland, foods are enriched with vitamin D and that has helped reduce the problems with vitamin D deficiency. Similar approaches could be adopted by other countries.

Many people – especially the older ones – do not get enough vitamin D

The summer sun is our main source of vitamin D but old people have difficulty with synthesizing the vitamin in their thin skin. There are other contributing factors such as spending too much time indoors, winter time, overweight, and the use of cholesterol-lowering statins that lower vitamin D levels. The daily reference intake (RI) level for adults in Denmark is 5 micrograms. The Danish health authorities recommend a daily 10-microgram vitamin D supplement for pregnant women, dark-skinned individuals, and people who do not get enough sunlight. A 20-microgram daily supplement is recommended for nursing home residents and people older than 70 years. Many scientists even say that the actual need for vitamin D may be a lot higher and their recommendations lie in the range between 30 and 100 micrograms daily.

Measuring vitamin D in the blood

Vitamin D levels in the blood are measured as 25-hydroxy-vitamin D. The official threshold value is 50 ng/ml but many scientists believe that more is needed and suggest as much as 75-100 ng/ml for optimal disease prevention

References

Niamh Aspell et al. Vitamin D deficiency Is Associated With Impaired Muscle Strength And Physical Performance in Community-Dwelling Older Adults: Findings From The English Longitudinal Study Of Ageing. Clinical Interventions in Aging. 2019

Trinity College Dublin. Vitamin D deficiency is associated with poor muscle function in adults aged 60+. ScienceDaily. 2019

Christian M. Girgis et al. Mice with myocyte deletion of vitamin D receptor have sarcopenia and impaired muscle function. Journal of Cachexia, Sarcopenia and Muscle, 2019