There are a number of essential water-soluble and fat-soluble vitamins that are required for good health and if there is deficiency this can lead to illnesses.
Water-soluble vitamins include B1 (thiamine), B2 (riboflavin), B6 (pyridoxine), B9 (folate), B12 (cobalamin), and C (ascorbic acid). Vitamins A, D and E are fat-soluble.
Thiamine deficiency is a well-known cause in psychiatry of memory impairment, particularly affecting long-term habitual excess use of alcohol (Wernicke Korsakoff). Other causes are malabsorption and recent gut surgery limiting gut absorption of thiamine.
A number of vitamin deficiencies cause fatigue. Several are associated with depression (B6 and B12).