Hello, Anorexia is a problem often associated with patients suffering from dementia. Side effects of Phenotoin sodium is swelling or bleeding of the gums. Keep gums healthy, massage should be done & teeth should be flossed to maintain good oral hygiene as lack of appetite may start from there. Other reasons for loss of appetite are ill-fitting dentures or insufficient physical activity. Dementia patients often forget to take food or beverages. You are suggested to give 6-8 small meals or snacks multiple times a day. You can include bread, fish, chicken, meats, pasta, potatoes, turkey, eggs, cheeses, milk, tofu, nuts, peanut butter, yogurt, peas, and beans in the diet. Monitor the vital signs, hydration level & electrolytes, help him stay physically active. If anorexia gets severe you may require to feed through a tube that s placed in the nose and goes to the stomach (nasogastric tube). Therapy(individual therapy, family therapy & psychotherapy) & lifestyle changes are effective. Treatment also include nutritional education & antidepressants do help to come out of anxiety & depression. He can continue taking vitamin B. Hope I have answered your query. Let me know if I can assist you further. Take care Regards, Dr. Nupur K