What vitamin deficiency is a 15-year-old female, who recently transitioned to a vegan diet, at greatest risk for developing?

Medical Advisory BoardAll articles are reviewed for accuracy by our Medical Advisory Board
Educational purpose only • Exercise caution as content is pending human review
Article Review Status
Submitted
Under Review
Approved

Last updated: April 11, 2025View editorial policy

Personalize

Help us tailor your experience

Which best describes you? Your choice helps us use language that's most understandable for you.

From the Guidelines

The correct answer is D) Vitamin B12 (cobalamin). This 15-year-old female who recently transitioned to a vegan diet is at greatest risk for developing vitamin B12 deficiency, as supported by the latest guidelines from the BMJ in 2024 1. Vitamin B12 is primarily found in animal products such as meat, fish, eggs, and dairy products. Since a vegan diet excludes all animal-derived foods, individuals following this diet pattern without proper supplementation are at high risk for B12 deficiency.

Key Points to Consider

  • The body stores vitamin B12, so deficiency symptoms may not appear for several months or even years after adopting a vegan diet.
  • Vitamin B12 is essential for proper nerve function, DNA synthesis, and red blood cell formation.
  • Deficiency can lead to megaloblastic anemia, neurological problems, and fatigue.
  • While other vitamins like B2, B6, A, and C can be obtained from plant sources in adequate amounts, B12 is uniquely challenging to obtain on a strictly plant-based diet, making supplementation or consumption of B12-fortified foods necessary for vegans, as highlighted in the guidelines 1.

Risk Factors

  • A diet low in vitamin B12, such as a vegan diet, is a common risk factor for deficiency, as stated in the guidelines 1.
  • Not consuming food or drinks fortified with vitamin B12 also increases the risk.
  • The patient's recent transition to a vegan diet without mention of supplementation or fortified food consumption places her at significant risk for vitamin B12 deficiency.

From the FDA Drug Label

A vegetarian diet which contains no animal products (including milk products or eggs) does not supply any vitamin B12. Patients following such a diet, should be advised to take oral vitamin B12 regularly The patient is at greatest risk for developing a deficiency in Vitamin B12 (cobalamin), as she has transitioned to a vegan diet three months ago and this type of diet does not supply any vitamin B12 2.

From the Research

Patient Risk Assessment

The patient, a 15-year-old female who recently transitioned to a vegan diet, is at risk for developing a deficiency in a specific vitamin. The key factors to consider are:

  • Age: 15 years
  • Diet: Vegan
  • Health status: No history of serious illness, takes no medications, and does not use any substances

Vitamin Deficiency Risk

Based on the patient's vegan diet, the risk of deficiency is highest for vitamins that are primarily obtained from animal products. The options are:

  • Vitamin A
  • Vitamin B2 (riboflavin)
  • Vitamin B6 (pyridoxine)
  • Vitamin B12 (cobalamin)
  • Vitamin C

Relevant Studies

Studies have shown that vegetarians and vegans are more vulnerable to vitamin B12 deficiency, which can lead to severe health risks such as megaloblastic anemia, cognitive decline, neuropathy, and depression 3, 4, 5, 6, 7. Vitamin B12 is an essential cofactor for two metabolic pathways and is obtained principally from food of animal origin.

Conclusion of Risk

Given the patient's vegan diet and the importance of vitamin B12 in human health, the patient is at greatest risk for developing a deficiency in:

  • Vitamin B12 (cobalamin)

This is because vitamin B12 is primarily obtained from animal products, and a vegan diet may not provide sufficient amounts of this vitamin. The patient's risk of deficiency can be mitigated with proper supplementation or dietary planning.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Vitamin B12 deficiency.

Nature reviews. Disease primers, 2017

Research

Vitamin B12 deficiency: issues in nursing care.

Medsurg nursing : official journal of the Academy of Medical-Surgical Nurses, 2004

Research

Vitamin B12 deficiency.

Vitamins and hormones, 2022

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

Have a follow-up question?

Our Medical A.I. is used by practicing medical doctors at top research institutions around the world. Ask any follow up question and get world-class guideline-backed answers instantly.