When I work individually with a child's diet I first look at is there a source of lutein, the substance most autistic children are trying naturally to avoid. (There are exceptions- the lutein cravers who must have OJ or strawberry something). I seek to remove the lutein source from the diet.

Next I look to see if the child's diet is heavily concentrated with
casein and gluten. The little opioid addicts. Then I look at the nutritional picture. What nutrients are in the diet and what is being supplemented.  Test results if available. Medications and possible interactions with nutrient levels in the body. 

Fat Soluble vitamins:

Vitamin A, if removing dairy then vitamin A must be supplemented as fish liver oil.
Vitamin D, supplied from sunlight and fortified dairy, also comes in the fish liver oil
Vitamin E, natural source wheat, vegetable oils and nuts primarily. So we specify the oils which supply some vitamin E: Olive oil (clear light) and soy
oil since many are afraid of wheat germ oil because of the source - although the germ oil is not protein it is fat.  Additional sources can be a multiple vitamin.
K (especially for those who bruise easily). Soy oil

Water soluble vitamins:

In the American diet the current research identifies fortified cereals as the primary source of B vitamins. Many non gluten cereals are NOT fortified. If
self-limited diet and gluten free probably needs a
B complex.

Folic acid -- fresh raw vegetables, chicken liver or again that multivitamin
Biotin, stays in the body a long time, rare to have a deficiency.Possible deficiency when eats heavy amounts of egg whites. Source cooked whole egg (many have allergies to egg), chicken.
B12, meats, some algae, sesame
Iron, wide distribution in foods. Deficiency common in autism. Good source unsulphured  black strap molasses, watermelon, oats, meats
Vitamin C, wide distribution in foods- fruits and vegetables.
Potassium, wide distribution in foods- banana, potato
Magnesium, nuts, sea salt
Calcium, wide distribution in foods
Manganese- primary sources cocoa and blueberry, some have high levels of manganese and should therefore avoid cocoa and blueberry. Others
benefit as manganese may be beneficial to some with epilepsy.
Iodine- sea salt, pineapple
Molybdenum (needed to make enzymes which are difficult for autists to manufacture as a result of low levels of transferases) sources- lamb, cabbage, tomato, oats, wheat. If no diet source then supplementing is a good idea.
Phosphorus- wide distribution in foods.

Acetylcholine precursors needed for speech (Koelle) and for manufacture of digestive enzyme sialic acid in saliva which kills bacteria and breaks down sugar:

1.
Soy oil
2.
DMG (N,N dimethylglycine) diet sources brown rice, yam and black walnut. Black walnut should be used in moderation it is used as a medicine in some cultures. Traditional meals often contain ingredients such as black walnut which are used for special occasions which havebeen passed down through the ages.
3.
arachidonic acid: Safflower oil, or from precursor black currant
4.
complex polysaccharides (root vegetables, fruits)
5.
choline foods: apple, butter, cauliflower, peanut butter, beef, lettuce, tomato, banana

Essential nutrients are widely distributed in foods. The diet can be complete with very few foods. Whole protein (meat, egg, nuts or a combination of grains and lentils) Fats are essential. Add some essential oils to the fried potato or rice.

If your child doesn't eat fruits or vegetables then a multiple vitamin is a good idea. This is meant to help comfort those using dietary intervention and who have children with limited but adequate diets. It is meant as a resource for those struggling with picky eaters. You can say-You get what you pay for- or-The best things in life are free

Cheers, Sandra
Help with Diet (from post)