Try to gain weight before treatment -- my husband's medical oncologist (MO) told him (at our first consult) "you are the perfect weight for your heighjt, but you will lose 20 pounds so my prescription for you is to gain weight in these next 3 weeks." Which he did, and he did lose 20 pounds (although half of that was actually right at end of treatment from two infections, a blood infection and a pneumonia, both of which ended him up in hospital. Maintaining adequate nutrition and hydration through radiation is difficult, be sure to consult with a hospital nutritionist experienced with cancer patients NOW and get advice on both. Will you be getting a PEG (gastric tube)?

As for supplements -- the only one which seems related to maintaining or regaining weight during cancer treatment is fish oil, there are several published studies and a number of on-going trials. Results have been promising, esp. in patitents with advanced cancer-related weight loss. Dosage in the trials varies, about 2000 mg a day fish oil seems common (about 2 capsules). The big capsules can be hard to swallow, there are other preparations available.

As for supplements, my husband's MO wanted him to stop taking any antioxidants (esp. vitamins E & C) during treatment, starting them again about 2 weeks after last radiation. She wanted him to continue taking 200 mg selenium/day as this element is a needed component of the immune system, has been related to better outcomes in HNC treatment, and we live in a low-selenium area (that is, are not apt to get enough from food/water).

However, as I have always said, do not take any supplements without clearing with your doctors. You could google "fish oil and cancer weight gain" and "selenium and cancer" to get some of the published studies.

Gail