I think you are just talking about minerals...as Protein and vitamins are equally important as well.

In minerals preferably Iron, potassium and zinc.....

Six Essential Nutrients for Hair Growth

Vitamins A and C: These two nutrients are important because they’re used as the building blocks of sebum, the substance that coats the outside of your hair follicles.

Food Sources: Most fresh vegetables provide an abundant supply of both vitamin A and C. Any you get at the grocery store will probably do.

Biotin: Also known as B7, biotin is used to synthesize Keratin Growth Factor, the hormone your body uses to synthesize Keratin, the protein that comprises the fibrous parts of your hair.

Food Sources:  beans, eggs, beef

Protein: Your hair is primarily a stick of protein with some hardened fatty acids coating it. Thus adequate protein is important for healthy hair. The amino acid lysine is particularly important, since it’s commonly found in keratin.

Food Sources: Any natural food source has to have protein in it, since it’s the building block of all cells. Fish, lean meats, legumes, and soy are all good sources.

Omega 3 and Omega 6 Fatty Acids: Your sebaceous gland uses a variety of fatty acids to create sebum, and Omega 3’s and Omega’s 6’s are the building blocks used to create the shiny coat that makes hair smooth.

In particular, alpha lonoleic acid is particularly robust for synthesizing the waxy sheath that coats the outer part of your hair.

Food Sources: flaxseed, salmon, hemp, canola oil, olive oil, brazilian nuts, walnuts

Iron: Iron is the mineral your body uses to convert testosterone to estrogen, which is an important hormonal regulator of hair growth. As I mentioned before, estrogen stimulates hair growth, while testosterone impedes it.

Iron deficiency is a common reason people start to get flaky hair that starts to shed.

Food Sources: Beef, poultry, nuts and legumes

Zinc: Zinc is an important regulator of a variety of different growth hormones which your body uses synthesize hair growth.

Food Sources: Nuts and legumes, seafood (especially oysters and shellfish), beef and chicken, dark leafy greens

Reference to http://blog.healthkismet.com/eating-for-healthy-hair