Vitamin B3, also known as niacin, is a crucial water-soluble vitamin essential for numerous bodily functions, including energy metabolism, DNA repair, and maintaining healthy skin, nerves, and digestion. When the body doesn't get enough of this vital nutrient, a specific and severe condition can develop.
The Answer: Pellagra
The correct answer to the question "Which disease is caused by the deficiency of vitamin B3?" is B. Pellagra. This disease, derived from the Italian words "pelle agra" meaning "sour skin," was first identified in the 1700s and reached epidemic proportions in some parts of the world where diets lacked variety, specifically those heavily dependent on corn without proper processing.
Pellagra is clinically identified by a set of symptoms often referred to as the "four Ds":
- Dermatitis: A distinctive, symmetrical, dark red rash that appears on sun-exposed areas of the body, such as the hands, feet, neck (known as Casal's collar), and face.
- Diarrhea: Gastrointestinal issues, including chronic diarrhea (sometimes bloody), abdominal pain, nausea, and a red, swollen tongue (glossitis).
- Dementia: Neurological and psychological symptoms that can range from fatigue, anxiety, and depression to confusion, memory loss, hallucinations, and severe nerve damage.
- Death: If left untreated, pellagra can be fatal within several years.
Understanding the Other Options
The other options presented in the question are caused by deficiencies in different vitamins:
- A. Beriberi: This condition is caused by a deficiency of vitamin B1 (thiamin). Symptoms primarily involve nerve damage and heart problems, leading to muscle weakness, tingling in limbs, and in severe cases, heart failure (wet beriberi) or paralysis (dry beriberi).
- C. Rickets: Rickets is a disorder caused by a lack of vitamin D, calcium, or phosphate, leading to the softening and weakening of bones in children, resulting in skeletal deformities such as bowed legs.
- D. Night Blindness: Difficulty seeing in dim light or darkness is an early symptom of a vitamin A deficiency. Severe deficiency can lead to permanent damage to the cornea and complete blindness.
Comparison Table: Vitamin Deficiencies
| Disease | Deficient Vitamin | Primary Symptoms |
|---|---|---|
| Pellagra | Vitamin B3 (Niacin) or Tryptophan | Dermatitis, diarrhea, dementia, death |
| Beriberi | Vitamin B1 (Thiamin) | Nerve damage, muscle weakness, heart problems |
| Rickets | Vitamin D, Calcium, or Phosphate | Softening/weakening of bones, skeletal deformities |
| Night Blindness | Vitamin A | Difficulty seeing in dim light, dry eyes |
Causes and Treatment of Pellagra
Primary pellagra is typically caused by a diet lacking sufficient niacin and tryptophan, a situation most commonly seen in developing regions where corn is the primary, untreated staple food. Corn contains niacin in a bound form that is not easily absorbed by the human body unless processed with alkali (nixtamalization), a traditional method used in Central America where pellagra is rare.
In developed nations, pellagra is uncommon but can occur due to secondary causes, with chronic alcoholism being the most frequent risk factor, as alcohol interferes with niacin absorption and metabolism. Other causes include malabsorption syndromes (e.g., Crohn's disease), certain medications (like isoniazid), and genetic disorders.
Treatment is straightforward and highly effective if caught early: oral or intramuscular niacin (specifically nicotinamide) supplementation, combined with a high-protein diet rich in B vitamins. Symptoms like diarrhea and skin lesions often improve within days or weeks of starting treatment.
Prevention Through Diet
Preventing pellagra is simple: a well-balanced diet. The recommended daily allowance (RDA) for adult men is 16 mg NE (niacin equivalents) and 14 mg NE for adult women. Excellent sources of niacin include:
- Animal Products: Beef liver, chicken breast, tuna, salmon, and red meat.
- Plant-Based Sources: Peanuts, mushrooms, avocados, green peas, potatoes, and fortified cereals and breads.
Ensuring adequate intake of diverse foods helps meet the body's niacin needs and prevents this serious, yet treatable, condition.
Conclusion
Pellagra is the specific and severe disease caused by a deficiency of vitamin B3 (niacin) or the amino acid tryptophan. Characterized by the progressive symptoms of dermatitis, diarrhea, and dementia, it can ultimately lead to death if left untreated. While rare in industrialized countries due to food fortification and varied diets, pellagra remains a public health concern in some developing regions and for individuals with specific underlying health conditions like chronic alcoholism. Early diagnosis and niacin supplementation are crucial for a full recovery.
