Hair thinning and brittle nails are getting bigger in women, day by day. and it can be linked to various factors, such as stress, hormonal imbalances, nutritional deficiency and other medical conditions. nutritional deficiencies like, iron, zinc, protein, biotin can cause the problem of nail and hair thinning. stress can also play a major role in weakened hair and nails by triggering hormonal imbalances. some disorders like hypothyroidism can also cause hair loss and brittle nails.
Here are some potential causes of brittle nails and hair thinning:
1- Nutritional deficiencies:

• Biotin Deficiency:- Biotin or vitamin B7 works to metabolize the amino acid in human body, that produces strong nails and hair. and when your body lacks biotin, problem of dry nails and hair occurs, resulting brittle nails and hair loss.
• Zinc Deficiency:- Zinc, grows and repairs our cell in body and deficiency of zinc can lead to hair loss and brittle nails.
• Protein Deficiency:- Lack of protein in body can affect hair and nails health.
• Iron Deficiency:- Low iron in body can causes brittle nails, fatigue and hair loss and dryness.

2- Thyroid Disorder:
A medical condition occurs by low level thyroid hormones in body, an underactive thyroid hormones causes fatigue, hair loss and nails strength.

3-Stress:

• Hormonal Imbalances:- Stress can affect our hormones which leads to hormonal changes or imbalances that causes hair loss and affects on health of hair and nails.
• Telogen Effluvium:- Stress pushes hair follicles into resting phase that leads thinning.

4- Other Medical Conditions:
Medications:- Some medications can affect your body and hair health, continuous consumption of high doze medicines leads to hair and nails dryness.
Other Factors:- Certain hair styling tools usage and treatments like, bleaching, dyeing and heat styling and nail treatment such as, frequent manicure, also contributes in hair thinning and brittle nails.

What to do:

• Dietary change
• Stress Management 
• Hair and nail care
• Consult a Dermatologist.