Hello!
Yes, it can be a contributor to mood struggles for sure. If you have the MTHFR mutation your body (which many people do), you will be unable to convert folic acid (the synthetic version of folate found in most supplements and some fortified foods), to l-methylfolate without the help of essential co-factors through foods and supplements that assist with this conversion. This genetic variation is common in folks with depressive symptoms, and can be helped by following many of the lifestyle factors encouraged here. Key pieces are make sure to eat plenty of dark leafy green vegetables and foods high in B12, support your digestive health with slow meals (to help release digestive enzymes) and adequate probiotics, and manage stress levels through exercise, meditation, fun, social connections, and emotional support.
Best to you! -Zoe