In the past the research I read on mind-body interaction tended to focus was on how mental distress can cause a person to feel physically unwell and certain mental health conditions, such as depression and anxiety, can cause somatic responses in certain parts of the body. For example, we have all experienced 'butterflies' before speaking in front of others or felt a lack of enthusiasm or energy to get out of bed.
In recent years nutritionists and other health professionals have advocated the need for a healthy diet and active lifestyle in the support of good mental health. Taking this idea further I recently read an article which talked about how imbalances found within the stomach and gut can impact a person's mental health. Depression and anxiety have been correlated to a reduced amount of good bacteria found in the gut. It is still unclear where the causational link lies but it has been suggested that a good, high quality probiotic taken daily can aid good mental health and support in the alleviation of feelings of depression and anxiety.
I support the notion "you are what you eat" and think that clients suffering from depression or anxiety may want to consider taking a probiotic supplement to support their mental health. As always it is important to consult a specialist who can give advice and consult with your doctor before taking any supplements.