Hi, your friend can consult a psychologist if he feels low due to BPD. Counselling sessions will help him. Your friend can consult a psychologist or psychiatrist about what foods to take to improve mood. There are certain foods that can improve mood such as foods rich in Omega 3 fatty acids, and foods rich in magnesium. Consult a psychiatrist about what foods to have.

Eating a balance of protective, nutrient-dense foods. These foods include fresh fruits, vegetables, legumes, whole grains, lean meats, cold-water fish, eggs, low-fat dairy, soy products, and nuts and seeds. These foods provide the levels of nutrients necessary to maintain good health and prevent disease

Hello human! I think it’s great that you’re going the extra mile by reaching out for a friend. To answer your question, foods like dark chocolate, mushrooms, yoghurt, citrus fruits and nuts are known to uplift mood. That being said, please remember that BPD is a serious medical condition. A psychological disorder that causes depressive and manic states may remain unaffected by external factors like food. These foods may not have a significant impact on your friend’s condition.

Hello, Mental health issues need Consultation with the professionals particularly when they are diagnosed with some issues like you mentioned BPD.Apart from medicines psychological consultation is also needed.By eating any food won't lift his mood,but yes when the mood is sad he should not disengage himself from routine activities, behavioral activation is to be followed. Tips work with those who dont have any diagnosable condition.