Below are lists of vitamins and minerals a rat should have and what they are for.  For estimated nutrient requirements, please visit the Nat' Academies Press.

Principle Ingredients

Ingredient Function Source Amounts Deficiency Signs
Carbohydrates (starches and sugars) Provide energy for daily activity, growth and reproduction. Grains, vegetables, seeds and nuts. Approx. 75% of the diet, more in growing, pregnant and nursing rats. Lack of activity, dull, un-playful, weight loss or growth/ reproduction failure; severe starvation and/or death.
Proteins (amino acids) Build body tissues (muscles, bones, nerves, hormones and blood, etc).  Excess converted to energy. Meat, grains, seeds and nuts. Minimum 7% in adults. Pregnant and growing rats need 15-20%.WARNING - excess protein is said to perhaps promote tumour growth. Weight/hair loss, fractures, infections, porphyrin staining, growth and/or reproduction failure.
Fats (fatty acids) Build body tissues and hormones.  Excess is used for energy or converted to fat stores. Meat, nuts and seeds.  Body can produce some on its own. Very little. Poor coat, scaly skin, failure to grow and/or reproduce.  Unlikely to occur.

Principle Vitamins

Vitamin Name Function Deficiency Signs Important In Diet?
A Needed for healthy skin, eyes, growth and reproduction. Scaly skin, blindness, failure to grow and/or reproduce, infections. Yes
B1 (thiamine) Energy production from carbohydrates and protein. Deterioration of brain, nerves,heart and muscle tissue, appetite loss, poor growth, weight Yes
B2 (Riboflavin) Growth and energy. Unhealthy skin on face and legs, failure to grow and/or reproduce. Yes
B6 Growth and energy. Failure to grow and/or reproduce, poor skin and coat. Yes
B12 Necessary for growth and healthy blood. Failure to grow, weakness, low fertility, even death. Yes, but deficiencies are pretty rare.
C Helps make cell walls, etc Wounds won't heal, failure to grow, bleeding. No, as rats make their own.
D Needed for healthy bones in adults and growing young rats. Failure to grow, abnormal joints, soft bones, stiffness. Yes
E Needed to repair damaged cells and tissue and for growth. Failure to grow and/or reproduce, abnormal bone, muscle and heart tissue. Yes
K Blood clotting. Bleeding doesn't stop even in minor wounds. Maybe - as it lives in the intestines, rats get this from eating their own faeces, which they do regularly.
Niacin Growth and energy. Poor coat and skin, weight loss, porphyrin staining. Yes
Folic Acid Growth and healthy blood. Poor growth, infections. No - as it lives in the intestines, rats get this from eating their own faeces, which they do regularly.
Pantothenic Acid Growth and energy. Rough coat, flaky skin, graying of hair, failure to grow and/or reproduce. Yes
Choline Works with Folic Acid and Vitamin B12. Liver and kidney damage. Yes
Biotin Needed for healthy skin and hair and reproduction. Hair loss, scaly skin. No - as it lives in the intestines, rats get this from eating their own faeces, which they do regularly.