What vitamin deficiency could be caused by a diet lacking fruits and vegetables?

Vitamin Deficiencies from Lack of Fruits and Vegetables

A diet lacking fruits and vegetables most commonly leads to deficiencies in vitamin C, folate (vitamin B9), and potentially vitamin A, with vitamin C deficiency being the most direct and clinically significant concern for morbidity and mortality.

Primary Deficiency: Vitamin C

Vitamin C deficiency is the most immediate risk when fruits and vegetables are eliminated from the diet, as these foods are the primary dietary sources. 1

• Low vitamin C status represents a potentially correctable contributing factor to morbidity and mortality, particularly affecting immune function 1
• Fresh fruits and vegetables are the main dietary sources; their absence results in lower body stores 1
• Clinical manifestations include bleeding gums, perifollicular hemorrhage, and frank scurvy in severe cases 1
• Citrus fruits, papaya, tomatoes, cabbage, potatoes, cantaloupe, and strawberries are the key food sources 1

Critical Secondary Deficiency: Folate (Vitamin B9)

Folate deficiency is highly likely without vegetable consumption, as green leafy vegetables, legumes, and citrus fruits are the primary natural sources. 1, 2

Clinical Significance

• Folate deficiency causes megaloblastic anemia, characterized by macrocytic red blood cells and abnormal white blood cell development 3
• Neuropsychiatric manifestations include depression, irritability, cognitive impairment, and in severe cases, psychosis 3
• Gastrointestinal symptoms include glossitis, angular stomatitis, and oral ulcers 3
• Green leafy vegetables, citrus fruits, legumes, nuts, and liver are the primary food sources 1, 2

Critical Diagnostic Pitfall

Before treating suspected folate deficiency, vitamin B12 status must always be checked, as folate supplementation can mask B12 deficiency while allowing irreversible neurological damage to progress. 3, 4, 5

• High folate levels during vitamin B12 deficiency can actually exacerbate anemia and worsen cognitive symptoms rather than simply masking them 5, 6
• The high-folate-low-vitamin B12 interaction can lead to combined degeneration of the spinal cord 5
• Neurological damage from B12 deficiency may be irreversible if treatment is delayed beyond 3 months 4

Additional Deficiency Risk: Vitamin A

• Yellow fruits and vegetables provide carotenoid precursors to vitamin A 1
• Deficiency leads to night blindness, xerophthalmia, and impaired resistance to infection 1

Diagnostic Approach

For a patient avoiding fruits and vegetables, the following laboratory evaluation should be performed:

1. Serum vitamin C level - to assess the most direct deficiency risk 1
2. Serum folate level (below 10 nmol/L indicates deficiency) 3
3. Red blood cell folate (below 340 nmol/L indicates deficiency) 3
4. Serum vitamin B12 level - mandatory before any folate supplementation 3, 4, 5
5. Complete blood count - to identify macrocytic anemia 3, 7
6. Homocysteine level - may be elevated in both folate and B12 deficiency 3

Treatment Recommendations

For Vitamin C Deficiency

• Include a small glass of unsweetened orange juice as one of five daily servings of fruits and vegetables 1
• Vitamin C supplementation may be needed if diet remains poor 1

For Folate Deficiency

• Oral folic acid 1-5 mg daily for mild to moderate deficiency 3
• For severe deficiency with clinical manifestations: 5 mg daily for minimum 4 months 3
• Always verify B12 status is adequate before initiating folate therapy 3, 4, 5

Dietary Modification Strategy

• Fortified breakfast cereals provide a practical and highly effective means of improving B vitamin and vitamin C status 1, 2
• This approach is particularly valuable when fresh produce consumption is limited 1

Common Clinical Pitfalls to Avoid

1. Never treat folate deficiency without checking B12 status first - this can worsen neurological damage in B12-deficient patients 3, 4, 5
2. Do not rely solely on blood count values - neurological and hematological manifestations may be inversely proportional 5
3. Recognize that vitamin B12 deficiency in younger adults is usually due to dietary restriction (veganism) or malabsorption, not pernicious anemia 8
4. Monitor patients periodically while taking vitamin supplements to prevent adverse interactions 5