Hair loss and thinning is very common amongst people that have very poor nutrition and simply aren't getting enough food such as those with anorexia or victims of a famine. This occurs because their body simply isn't getting enough food of any type.
If you don't have anorexia, you could be getting inadequate protein because of the following factors:
- Poor appetite
- Not being adequately fed. For example if you have dementia you might need help to eat but that help may not be consistently available
- Swallowing problems resulting in you under eating
- Taking multiple medications that mess around with the absorption of nutrients into your body
- Depression that causes you to under eat
- Alcoholism that results in you eating a very unbalanced diet
According to The Science of Black Hair, low protein diets produce weak, protein deficient hair shafts. These protein deficient hair shafts [are] found to be more brittle than normal hairs, and they also lack the colour, natural curl pattern and texture of normal hairs. Protein deficiency can cause hair to stop growing all together. That said, protein deficiency is very uncommon in the Western world or even amongst the middle and upper classes in the Developing world.
- All meats including fish, chicken, other poultry and pork
- Dark leafy vegetables, e.g. kale, collards, spinach
- Whole grains including rice bran
Vegetables have the added benefit of containing fibre, antioxidants, many vitamins and minerals.
Protein deficiency may cause hair loss (Natural News)
Protein deficiency and hair loss (LiveStrong)