From the weight you wrote, you are approximately 30lbs underweight for your height.You do need extra nutrients to gain some weight. From the literature, ITP is not a diet related disease or triggered by diet. You can take supplements, however, you would benefit more from the foods you eat. Suggest eating a moderate fat diet to gain weight slowly, protein (amino acids) and eat healthy. Moderate fat diet means = use polyunsaturated (omega 3, corn oil, nuts, etc) fats and monounsaturated (olive oil, canola oil, peanut oil, etc) fats, no saturated fats (high fat snack foods, butter, fat spreads) and no trans fats. Eat low fat meats (chicken, fish) or non-meat sources (soy products, nuts), low fat vegetarian combinations (rice & beans, pasta & beans, low fat cheese & pasta), low fat and substitute dairy products (1% milk, low fat/fat free yogurts, low fat soy milk/soy yogurt), use plant oils, non trans-fat margarines, and eat a lot of fruits and vegetables. Eat daily high fiber breads and cereals (oatmeal). This diet will help give you the protein you desire in supplements if you consume meats or dairy or vegetarian combinations at each meal daily. Hoped this helped you.