Deficiency Diseases

Part of Nutrition Science

The classic nutritional deficiency diseases — their causes, symptoms, diagnosis without laboratory testing, and treatment with available foods.

Why This Matters

Deficiency diseases represent the body’s response to sustained absence of specific nutrients. They were endemic in populations subsisting on monotonous diets for most of human history — and they will return in any collapse scenario where dietary diversity collapses or where staple crops change without adaptation. Scurvy killed sailors on long voyages; pellagra devastated populations that switched to maize without traditional lime processing; beriberi struck Asian populations living on polished rice; rickets affected children in industrial cities.

The pattern is always the same: a population transitions to a narrow dietary base; a deficiency develops silently over weeks to months; then characteristic symptoms appear that historical observers often misattributed to infection, miasma, or moral failure before the nutritional cause was identified. In a rebuilding community, a health worker who recognizes these patterns can intervene before the disease reaches its severe stage — and can prevent it entirely if the cause is understood.

This article covers the major deficiency diseases in order of global significance: scurvy, pellagra, rickets/osteomalacia, and beriberi. Iodine deficiency (goiter and cretinism) and iron deficiency anemia are covered in dedicated articles.

Scurvy (Vitamin C Deficiency)

Pathophysiology: Vitamin C (ascorbic acid) is required for the synthesis of collagen, the structural protein in connective tissue, blood vessel walls, bone matrix, and skin. Without vitamin C, collagen cannot be synthesized properly — existing collagen breaks down, and new synthesis fails. The body literally falls apart.

Who is at risk: Any person who goes without fresh fruits or vegetables for more than 4-8 weeks. The body stores approximately 1,500 mg of vitamin C; at a typical adult need of 60-90 mg per day with zero intake, stores deplete in 30-50 days. Risk groups: sailors on long voyages historically; soldiers on prolonged campaigns; communities cut off from fresh produce; infants fed only cow’s milk (very low in vitamin C); elderly on monotonous diets.

Signs and symptoms (in order of appearance):

1. Weeks 4-6 without vitamin C: Fatigue, malaise, irritability
2. Weeks 6-8: Follicular hyperkeratosis (small bumps around hair follicles, especially on the thighs and upper arms)
3. Weeks 8-10: Gum changes — swollen, inflamed, bleeding gums (especially around the teeth)
4. Weeks 10-12: Perifollicular hemorrhage (red spots around hair follicles); joint pain and swelling
5. Advanced: Teeth loosen and fall out; old wounds reopen; large bruises under the skin; anemia; bone pain (especially in children)
6. Terminal: Infection, hemorrhage, sudden cardiac death

Diagnosis without laboratory testing: Gum examination is the most reliable clinical sign. Healthy gums are firm, pale pink, and do not bleed when lightly touched. In scurvy, gums are dark red, swollen, spongy, and bleed easily. The pattern of bleeding around hair follicles on the thighs is also characteristic. History of dietary vitamin C absence for 6+ weeks with these signs is sufficient for clinical diagnosis.

Treatment: Vitamin C is the treatment. Fresh citrus fruit (1-2 oranges per day), kiwi, guava, fresh peppers, or any fresh vegetables containing vitamin C. Improvement begins within 24-48 hours of starting supplementation — the first sign is often a dramatic improvement in how the patient feels. Gum bleeding resolves within a week; more advanced signs take longer.

Prevention: Humans cannot synthesize their own vitamin C (unlike most mammals) — this is likely a historical mutation when our frugivorous ancestors ate sufficient vitamin C daily without needing to synthesize it. Any community needs a regular source of fresh plant food. Even small amounts — 10 mg per day prevents scurvy; 60 mg prevents and treats it — are sufficient.

Vitamin C-rich foods per 100g:

• Guava: 228 mg
• Bell peppers (raw): 150 mg
• Kiwi: 93 mg
• Orange: 53 mg
• Broccoli (raw): 89 mg
• Kale (raw): 120 mg
• Parsley: 133 mg
• Rosehips: 426 mg (the richest plant source known)
• Pine needle tea (traditional prevention among indigenous peoples): significant vitamin C content

Pellagra (Niacin / B3 Deficiency)

Pathophysiology: Niacin (vitamin B3) is required for NAD and NADP — coenzymes involved in hundreds of metabolic reactions, particularly energy metabolism and DNA repair. Pellagra typically occurs when maize (corn) becomes the dietary staple without traditional lime processing (nixtamalization) — maize contains niacin in a bound form (niacytin) that is not bioavailable unless the grain is treated with alkali.

The 4 D’s of Pellagra:

1. Dermatitis: Symmetrical skin rash in sun-exposed areas — hands, forearms, neck, face. The rash has a distinct sunburn appearance, becomes dark and rough, and may peel or crack. The characteristic “Casal’s necklace” is a ring of inflamed skin around the neck.
2. Diarrhea: Gastrointestinal inflammation; mucous membranes of the mouth, esophagus, and gut affected.
3. Dementia: Neurological symptoms — confusion, memory loss, aggression, hallucinations, depression, in severe cases psychosis.
4. Death: Without treatment, pellagra progresses to death, typically from systemic infection.

Diagnosis: Clinical — the combination of symmetrical sun-exposed dermatitis with gastrointestinal and neurological symptoms in a person eating a maize-dominant diet is diagnostic.

Treatment: Niacin (nicotinic acid) supplementation plus dietary improvement. Niacin is found in: meat and poultry (high), fish (high), peanuts, legumes, whole grains (especially those nixtamalized). The body can also synthesize niacin from tryptophan (an amino acid) — adequate protein intake with dairy, eggs, or meat provides tryptophan that partially compensates.

Prevention: Traditional nixtamalization (soaking and cooking maize in lime water — calcium hydroxide solution) releases bound niacin and dramatically improves the nutritional profile of maize. This is why pellagra was not a disease of Mexico (where maize originated and nixtamalization was traditional) but became an epidemic when maize spread to Europe and the American South without the traditional preparation method.

In any community transitioning to maize as a staple: ensure nixtamalization, provide protein sources, include other grains and legumes to supplement niacin intake.

Rickets and Osteomalacia (Vitamin D / Calcium Deficiency)

Pathophysiology: Vitamin D is required for calcium absorption from the gut. Without it, the body cannot adequately mineralize bone matrix — bones remain soft (unmineralized osteoid).

In children, this causes rickets. In adults, it causes osteomalacia (soft bones). The conditions are the same pathology at different life stages.

Signs of rickets in children:

• Bow legs or knock-knees (bone deformation under weight-bearing)
• Bowing of the wrists and enlargement of the wrist joints
• Soft skull (craniotabes) — the skull feels soft and springy when pressed
• Delayed closure of fontanelles
• Frontal bossing (prominent forehead from compensatory bone thickening)
• Rib “rachitic rosary” — enlarged costochondral junctions visible as bumps along the ribs
• Delayed tooth eruption and defective enamel
• Short stature

Signs of osteomalacia in adults:

• Bone pain (particularly back, hips, legs)
• Muscle weakness
• Waddling gait
• Stress fractures from minor trauma

Risk factors:

• Limited sun exposure (indoor life, heavy clothing covering skin, high-latitude winters, air pollution)
• Dark skin (requires more sun exposure for equivalent vitamin D production)
• Exclusively breastfed infants whose mothers are vitamin D deficient (breast milk is low in vitamin D)
• Malabsorption conditions

Treatment: Vitamin D supplementation (if available) or intensive sun exposure for vitamin D production. Diet: fatty fish, egg yolks, liver. Calcium supplementation alongside vitamin D. Bone deformities in severe rickets may partially correct with treatment but severe bowing may require surgical correction.

Beriberi (Thiamine / B1 Deficiency)

Pathophysiology: Thiamine is required for carbohydrate metabolism and nerve function. Deficiency causes energy failure in high-demand tissues: the nervous system and the heart.

Two forms:

Wet beriberi: Cardiovascular form. The heart muscle fails and fluid accumulates (edema). Signs: swollen legs and face, rapid heart rate, enlarged heart, shortness of breath. Can cause sudden heart failure.

Dry beriberi: Neurological form. Peripheral neuropathy — numbness and tingling in feet and hands, weakness, difficulty walking, wrist/foot drop. Can progress to Wernicke’s encephalopathy (eye movement abnormalities, ataxia, confusion) — a brain emergency.

At-risk populations: Communities subsisting on polished white rice (husk and bran removed — where the thiamine lives). Historically affected East and Southeast Asia when rice milling technology improved enough to produce white rice at scale. Also affects alcoholics (alcohol blocks thiamine absorption).

Treatment: Thiamine replacement — ideally parenteral in severe cases. Wet beriberi responds dramatically to thiamine (improvement in hours). Dry beriberi responds more slowly; permanent nerve damage may remain.

Prevention:

• Eat brown rice (unpolished) or parboiled rice (the parboiling process drives thiamine from the bran into the endosperm before polishing)
• Eat varied diet including legumes, pork, whole grains (all thiamine-rich)
• Do not over-boil rice or discard cooking water — thiamine leaches into water

Summary Table

Disease	Deficient nutrient	Key visual sign	Fastest dietary treatment
Scurvy	Vitamin C	Bleeding gums	Any fresh fruit or vegetable
Pellagra	Niacin (B3)	Sun-exposed skin rash	Meat, peanuts, nixtamalized maize
Rickets	Vitamin D + Calcium	Bowed legs (children)	Sun exposure, fatty fish, eggs
Beriberi	Thiamine (B1)	Swollen legs (wet) / numb feet (dry)	Brown rice, legumes, pork
Scurvy	Vitamin C	Gum changes	Citrus, peppers, pine needles

Deficiency diseases are sentinel events — their appearance announces that the community’s food system has failed in a specific way. Treating the individual patient addresses the immediate crisis; understanding and correcting the dietary pattern prevents the next hundred cases.