The recommended daily intake of vitamin D for adult women is generally around 600 International Units (IU) or 15 micrograms (mcg) per day. For women over 70 years old, the recommendation increases to about 800 IU or 20 mcg daily. Pregnant and breastfeeding women are also advised to get around 600 IU per day. Some experts suggest that higher doses of about 1,000 to 2,000 IU daily may be safe and beneficial for many adults, but doses above 4,000 IU should not be taken without medical supervision. The best way to ensure adequate vitamin D levels is through a combination of sun exposure, diet, and supplements if necessary, ideally guided by a healthcare provider's advice and possibly blood testing.