Following is a list of all the eight types of Vitamin B and what a deficiency of each of them can cause:
Vitamin B1 (thiamine): A lack of this vitamin can cause beriberi and Korsakoff's syndrome.
Vitamin B2 (riboflavin): Deficiency causes ariboflavinosis of which some symptoms are cracks in the lips, highly sensitive to sunlight, angular cheilitis and inflammation of the tongue.
Vitamin B3 (niacin and nicotinamide): A lack of this type can cause pellagra. The symptoms include of this disease are aggression, dermatitis, insomnia, weakness, mental confusion, and diarrhea. In advanced cases, pellagra may lead to dementia and death.
Caution: Exceeding the 35 mg/day can lead to redness of the skin, often accompanied by itching or a mild burning sensation. Nausea, vomiting, and signs and symptoms of liver toxicity can occur when taken 3000mg/day of nicotinamide and 1500 mg/day of nicotinic acid.
Vitamin B5 (pantothenic acid): Deficiency can result in acne and paresthesia, although this is not very common.
Vitamin B6 (pyridoxine, pyridoxal, and pyridoxamine): A deficiency can result in anemia, depression, dermatitis, high blood pressure or hypertension, water retention, and elevated levels of homocysteine.
Caution: Exceeding the 100 mg/day can cause neuropathy and skin diseases.
Vitamin B7 (biotin), also known as vitamin H: A lack of this type of Vitamin B usually has no real effect on adults; it can lead to impaired growth and neurological disorders in infants though.
Vitamin B9 (folic acid), also known as vitamin M: A deficiency results in a macrocytic anemia and elevated levels of homocysteine. Supplementation is often recommended during pregnancy due to the fact that a deficiency can lead to a birth defect. Studies and research has shown that folic acid could also slow down aging of the brain.
Caution: Exceeding the 1 mg/day could cover up a B12 deficiency which can lead to permanent neurological damage.
Vitamin B12: Deficits resulting from a lack of Vitamin B12 are macrocytic anemia, elevated homocysteine, peripheral neuropathy, memory loss and other brain and memory related failures. With aging, the absorption through the gut decreases. Therefore these diseases occur more often among the elderly. It can also cause pernicious anemia, which is an autoimmune disease displaying symptoms of mania and psychosis and in rare extreme cases even paralysis.
The only source to ensure you get all the vitamins B is by taking a Vitamin B complex supplement. The best thing to do of course is a healthy food intake, but that might not always be feasible and/or possible.
What we can ensure though is to get our daily, healthy dose of God's word. That is always possible and feasible.
Deuteronomy 17:19 And it shall be with him, and he shall read it all the days of his life, that he may learn to fear the LORD his God and be careful to observe all the words of this law and these statutes,