Most people associate a vitamin C deficiency with images of scurvy-ridden sailors. But even low levels of vitamin C can affect your health and functioning. Here are some of the signs of low vitamin C levels: frequent infections and poor immunity; skin that's bumpy and rough or dry and damaged; joints that are painful and swollen; weak bones and increased bone loss; bleeding gums and teeth that are unhealthy; wounds that are slow to heal; easy bruising and low iron levels; constant fatigue; low mood or depression.