Could vitamin D prevent you from losing muscle strength as you age?

Vitamin D is a fat-soluble vitamin made from cholesterol in the human body. It’s important in the absorption of calcium and phosphorus, which are essential for strong bones and teeth. Vitamin D is produced in the body when the skin is exposed to sunlight, but small amounts of it can also be found in certain foods, including fish and eggs.

Scientific findings suggest that vitamin D isn’t just important for bone and dental health. In fact, it’s also important for the entire musculoskeletal system – and possibly other aspects of health. One example is the discussion surrounding whether vitamin D may play a protective role in cardiovascular disease [1], cancer [2], neurological [3] and autoimmune diseases [4], and infections [5]. Vitamin D deficiency can lead to osteoporotic fractures [6], rickets [7] in children, and other health [8] problems.

Vitamin D and strength

In a large-scale study, Delinocente et al. [9] investigated the relationship between vitamin D (25-hydroxyvitamin D) and age-related decline in neuromuscular strength (dynapenia). The study sample comprised 3,205 people aged 50 and above, and only included individuals without dynapenia (hand dynamometer grip strength greater than or equal to 26 kg in men and greater than or equal to 16 kg in women). The participants were tracked over a four-year period. At the beginning of the experiment, the study participants’ vitamin D levels were determined according to their serum concentrations of 25-hydroxyvitamin D and classified as:

• sufficient (> 50 nmol/L)
• insufficient (30–50 nmol/L)
• deficient (<30 nmol/L)

The analyses showed that 30 per cent of the test subjects had insufficient serum concentrations of vitamin D, with 22 per cent actually having a vitamin D deficiency.

Among those who had adequate levels of vitamin D over the 4-year study, dynapenia occurred at a rate of 13.1 cases per 1,000 people per year. As for the people with an insufficient vitamin D level, the incidence of dynapenia was higher, at 20.2 cases per 1,000 persons per year. And the highest incidence of dynapenia? That was found among participants with a vitamin D deficiency, at a rate of 27.4 cases per 1,000 persons per year.

The study’s key finding is that vitamin D deficiency is a risk factor for dynapenia. Individuals deficient in vitamin D (< 30 nmol/L) had a 70 per cent higher risk of developing dynapenia by the end of the study period than individuals with normal vitamin D levels (> 50 nmol/L).

If people with osteoporosis and individuals taking vitamin D supplements are excluded from the analysis, the threshold for risk is even higher (greater than or equal to 50 nmol/L). This means that in these individuals, both vitamin D deficiency (< 30 nmol/L) and an insufficient serum concentration of vitamin D (between 30 and 50 nmol/L) are risk factors for dynapenia. The researchers were able to demonstrate that the risk of developing muscle weakness at the end of the four-year period was 78 per cent higher in individuals with vitamin D deficiency at baseline than in those with normal vitamin D levels. People with insufficient vitamin D (30-50 nmol/L) were at a 77 per cent higher risk of dynapenia.

More than half of the global population has either a vitamin D insufficiency or deficiency [10,11]. Many of those affected are elderly. Due to the lack of sunlight in winter, however, children and young adults can also be deficient in vitamin D.

Here are the vitamin D amounts recommended by the Federal Office of Public Health:

• Age 59 and over: 800 IE per day
• Age 1–58: 600 IE per day
• Age 0-12 months: 400 IE per day

Verdict

As the results of this study demonstrate, it’s important to take vitamin D if you have a deficiency or insufficiency. Not having enough vitamin D puts you at risk of losing muscle strength. Sunshine, vitamin D-rich foods or supplements, and strength training are recommended in order to maintain muscle strength as we age. That being said, more clinical trials are needed to investigate whether a therapeutic combination of strength training and vitamin D supplementation in individuals with dynapenia and vitamin D deficiency increases muscle strength at age 50 and above.

So head into the sunshine or make sure you’re getting enough vitamin D from your diet and combine it with strength training. Remember, you have the power to impact your strength and muscle mass as you age.

References

1. Zhou A, Selvanayagam JB, Hyppönen E. Non-linear Mendelian randomization analyses support a role for vitamin D deficiency in cardiovascular disease risk. Eur Heart J. Oxford Academic; 2022;43: 1731-1739. doi:10.1093/EURHEARTJ/EHAB809

2. Chandler PD, Chen WY, Ajala ON, Hazra A, Cook N, Bubes V, et al. Effect of Vitamin D3 Supplements on Development of Advanced Cancer: A Secondary Analysis of the VITAL Randomized Clinical Trial. JAMA Netw Open. American Medical Association; 2020;3. doi:10.1001/JAMANETWORKOPEN.2020.25850

3. Shea MK, Barger K, Dawson-Hughes B, Leurgans SE, Fu X, James BD, et al. Brain vitamin D forms, cognitive decline, and neuropathology in community-dwelling older adults. Alzheimer's Dement. John Wiley & Sons, Ltd; 2022; doi:10.1002/ALZ.1283

4. Hahn J, Cook NR, Alexander EK, Friedman S, Walter J, Bubes V, et al. Vitamin D and marine omega 3 fatty acid supplementation and incident autoimmune disease: VITAL randomized controlled trial. BMJ. British Medical Journal Publishing Group; 2022;376. doi:10.1136/BMJ-2021-066452

5. Taha R, Abureesh S, Alghamdi S, Hassan RY, Cheikh MM, Bagabir RA, et al. The Relationship Between Vitamin D and Infections Including COVID-19: Any Hopes? Int J Gene Med. Dove Press; 2021;14: 3849. doi:10.2147/IJGM.S317421

6. Larsen ER, Mosekilde L, Foldspang A. Vitamin D and Calcium Supplementation Prevents Osteoporotic Fractures in Elderly Community Dwelling Residents: A Pragmatic Population-Based 3-Year Intervention Study. J Bone Miner Res. John Wiley & Sons, Ltd; 2004;19: 370–378. doi:10.1359/JBMR.0301240

7. Sahay M, Sahay R. Rickets-vitamin D deficiency and dependency. Indian J Endocrinol Metab. Wolters Kluwer -- Medknow Publications; 2012;16: 164. doi:10.4103/2230-8210.93732

8. Amrein K, Scherkl M, Hoffmann M, Neuwersch-Sommeregger S, Köstenberger M, Tmava Berisha A, et al. Vitamin D deficiency 2.0: an update on the current status worldwide. Eur J Clin Nutr 2020 7411. Nature Publishing Group; 2020;74: 1498-1513. doi:10.1038/s41430-020-0558-y

9. Delinocente MLB, Luiz MM, de Oliveira DC, de Souza AF, Ramírez PC, de Oliveira Máximo R, et al. Are Serum 25-Hydroxyvitamin D Deficiency and Insufficiency Risk Factors for the Incidence of Dynapenia? Calcif Tissue Int. Springer; 2022;111: 571–579. doi:10.1007/S00223-022-01021-8/TABLES/3

10. van Schoor N, Lips P. Worldwide Vitamin D Status. Vitam D Fourth Ed. Academic Press; 2018;2: 15-40. doi:10.1016/B978-0-12-809963-6.00059-6

11. Mithal A, Wahl DA, Bonjour JP, Burckhardt P, Dawson-Hughes B, Eisman JA, et al. Global vitamin D status and determinants of hypovitaminosis D. Osteoporos Int. Springer London; 2009;20: 1807-1820. doi:10.1007/S00198-009-0954-6/METRICS