As we get older, our skeletal muscle mass, strength, and power to move gradually decline, which may lead to a condition called sarcopenia. Sarcopenia affects more than 50 million people over the age of 50 years worldwide and contributes to type 2 diabetes, frailty, physical disability, loss of independence and poor quality of life. So it’s an important condition to prevent during aging to minimize both personal and societal costs.
Currently, there are limited solutions for treating sarcopenia, so early intervention, before symptoms become too severe, is preferable. Most research has focused on the effect of increasing protein intake to prevent or treat sarcopenia.
But very few studies have actually investigated the importance of dietary vitamin C with loss of skeletal muscle mass and function in middle and older age. Our new paper shows that the more dietary vitamin C middle-aged and older adults consume, the greater their skeletal muscle mass.
Vitamin C is already known to play an important role in bone health, but may also help us maintain strong muscles. This vitamin is only found in vegetables, potatoes, and fruits.
People who don’t consume enough of these in their diet are at risk of vitamin C deficiency, which may cause weakness, tiredness and fragile bones. In extreme cases, it may lead to scurvy. But before this occurs, insufficient dietary vitamin C intake may have other effects on health, including our muscles.
Around two-thirds of our body’s total vitamin C is found in skeletal muscle. It’s used for making carnitine, a crucial substance that provides energy for muscles to function, and collagen, which is an essential structural component of muscle.
In addition, vitamin C is a strong antioxidant that can help to counteract free radical molecules, which increase when we age. Unopposed, these free radicals can contribute to the destruction of muscle cells.
Skeletal muscle mass
Our study looked at data collected from over 13,000 men and women in the European Prospective Investigation into Cancer and Nutrition Norfolk cohort, aged 42-82 years. We used bioelectrical impedance analysis – which sends small electrical signals through the body to calculate water and fat percentage – to estimate the proportion of skeletal muscle in the body.
Participants also completed a diary of everything they ate and drank over seven days so we could accurately calculate their intake of dietary vitamin C. We grouped people according to their intake of vitamin C, ranging from low to high.
Vitamin C was also measured directly in their blood, providing results less susceptible to potential error in reporting diet. This allowed us to classify people according to whether they had sufficient vitamin C intake.
Our statistical analysis took into consideration other important factors, including participant’s physical activity, protein and energy intake, which might also have effects on skeletal muscle mass.
We found that the people in our study who consumed the highest amount of vitamin C in their diet had the greatest muscle mass. The biggest difference was seen in women: those women in the highest category of vitamin C consumption had muscle mass 3% greater than those in the lowest category.
These differences are likely to be clinically relevant, especially given that most people are estimated to lose 0.5% to 1% of muscle mass every year after age 50.