Walgreens carries a sublingual B12 supplement, which I am tempted to take. Do you think it will help? Is there some other factor that could be causing me to feel this way? Any suggestions you can give me would be greatly appreciated.

DEAR READER: Vitamin B12 deficiency would cause a number of significant signs, including fatigue, before it would cause true narcolepsy, a chronic sleep disorder. People suffer daytime drowsiness and drop off to sleep at inappropriate times without warning. They may awaken feeling refreshed, fall asleep again, and repeat the pattern. Sleep paralysis may occur, accompanied with vivid dreams and an inability to speak or move during falling asleep or waking.

Diagnosis might be accomplished through polysomnography at a sleep center, a sleep latency test that determines how long it takes a person to fall asleep, detailed sleep records and a sleep history presented to your doctor.

Vitamin B12 deficiency is relatively rare because the body stores several years worth at a time and a healthful diet to include seafood, milk, cheese and eggs is readily available; however, those with pernicious or megaloblastic anemia, Crohn’s, celiac or Grave’s disease, lupus and excessive alcohol consumption, as well as vegetarians, vegans and the elderly, may be at increased risk.

Oral B12 tablets are reported to contain more of the vitamin than is available through injection; however, they are not absorbed as well as the injectable form. I recommend you speak with your primary-care physician to be assured this method is appropriate for you. You should also undergo routine lab testing and perhaps X-rays to rule out other conditions to explain your fatigue. Only then can you get to the bottom of the issue.

To provide related information, I am sending you a copy of my Health Report “Vitamins and Minerals.” Other readers who would like a copy should send a self-addressed stamped No. 10 envelope and a $2 check or money order made payable to Newsletter and mailed to Newsletter, P.O. Box 167, Wickliffe, OH 44092-0167. Be sure to mention the title or print an order form off my website at www.AskDrGottMD.com.

DEAR READER: There are 13 vitamins that your body needs, all essential for maintaining good health. These are broken down into two categories, water soluble and fat soluble. The water-soluble vitamins include the B complex, which is comprised of eight vitamins — 1, 2, 3, 5, 6, 12, biotin and folic acid — and C. The fat-soluble vitamins are A, D, E and K.

B1 (thiamin) works with the nervous system and helps the body use carbohydrates for energy. When deficiency occurs, it can cause impaired growth, muscle weakness, mental confusion and more.

B2 (riboflavin) helps the body process protein, carbohydrates and fats. It works to support good vision, healthy skin and the production of red blood cells. Deficiency can cause fatigue, slowed growth, swollen/sore throat and more.

B3 (niacin) assists the body in processing proteins and fats. It also helps the skin, digestive tract and nervous system to remain healthy. Deficiency can result in diarrhea, weakness, skin disorders and pellagra. Excesses can cause stomach upset, skin flushing and itching, and rash. The most common cause of too much niacin is from supplemental niacin taken to reduce cholesterol levels; therefore, it should be introduced gradually to prevent unwanted side effects.

B5 (pantothenic acid) helps the body process nutrients and synthesizes hormones and cholesterol. Deficiency is uncommon.

B6 (pyridoxine) aids in the formation of red blood cells and maintains brain function. Deficiency can cause kidney stones, anemia and nausea. Excess can cause leg pain and more.

B12 (cyanocobalamin) maintains red blood cells, is important for metabolism and the maintenance of the central nervous system, and helps to make DNA. Deficiency can result in pernicious anemia and tingling of the fingers and toes.

Biotin helps metabolize fats and carbohydrates. Deficiency is rare.

Folic acid/folate prevents birth defects and makes DNA and new red blood cells. Deficiency can cause anemia, diarrhea and other symptoms.

C (ascorbic acid) is an antioxidant necessary for the growth and repair of tissues. It helps repair bones, teeth and cartilage. Excesses can cause kidney stones, upset stomach and an increase in iron absorption.

A (retinol) is necessary for good vision, bone and tooth development and several other functions. Excesses can result in nausea, headache, blurred vision, vomiting and an increased risk of developing osteoporosis.

D (calciferol) helps teeth and bones stay healthy. Deficiency can result in osteoporosis, fractures and rickets (in children). Excesses can cause diarrhea, constipation, weakness and other problems.

E (tocopherol) acts as an antioxidant that helps the body utilize vitamin K and works to form red blood cells. Deficiency is rare because E is stored naturally in the body for extended periods of time. Excesses include possible hemorrhage and impairment of blood clotting.

K helps with the formation of bone and aids blood clotting. Low levels can lead to excessive bleeding. Excesses can cause liver damage.

People who maintain a well-balanced, healthful diet should not experience deficiency or excesses of vitamins unless there is an underlying condition that alters metabolism. Problems caused by excess consumption come into play primarily when supplements are used inappropriately or unnecessarily. Deficiency is most common in people who don’t eat properly, take medications that reduce a vitamin’s efficiency, or are vegetarian or vegan.

To provide more extensive information, I am sending you a copy of my Health Report “Vitamins & Minerals.” Other readers who would like a copy should send a self-addressed stamped No. 10 envelope and a $2 check or money order to Newsletter, P.O. Box 167, Wickliffe, OH 44092-0167. Be sure to mention the title or print an order form off my website at www.AskDrGottMD.com.