Please excuse my lengthy post of concern, I have nowhere else to turn for advice.

My friend is an adult and suffered a bout of stomach bug with vomiting. After seeking help from the medical center she stumbled upon an Internet diagnosis of histamine imbalance where both too little and too much is the culprit.

She has searched far and wide but so far been unable to find a doctor willing to accept this as it is not a disease known to medical science (they are all incompetent, she says).

For three years since she has had herself on this especially strict diet which requires impeccable food handling, fresh, lean produce free of flavor and very very specific food items. She eats less than 10 food items: cod, chicken, apple, oats, canola oil, iodine-free sea salt, blueberries, cauliflower, carrot and zucchini.

She dropped 17kgs in a couple of months and supplements herself with canola oil to make up for the daily energy deficit.

We used to love going out for meals together, enjoying wine and travelling to eat well and drink well in restaurants and cafe's. This is no longer possible. She eats only food she cooked herself and only using her own utensils. Spending a whole day outside the home is impossible.

In all honesty maybe her extreme diet is the epitome of healthy, but the excessive control and limitation of life is not. Before this she lost her career and moved as a trailing spouse. She has not made friends in the past 9 years as an expat. She lives a life of daily waiting for her spouse to come home from work and hobbies. He eats normally and is respectful of her.

She takes a liking to pitying herself and every meal is a conversation about what she would want to eat if only she could. Or lengthy descriptions of how much she vomits if she eats the faintest dusting of black pepper or a drop of lactose free milk.

It's now been almost two years since the last time she got sick.

I don't know how to help my friend. Am I wrong to assume this is an eating disorder? Am I selfish for wanting to share a normal meal with my friend?