Is Vitamin B12 or D the Hardest Vitamin to Get Naturally?

November 16, 2025 •

2 min read

According to the National Institutes of Health, approximately 12.5% of adults aged 19 and older have a Vitamin B12 insufficiency, while Vitamin D deficiency is also widespread globally. This raises the question: what is the hardest vitamin to get naturally, and what factors make it so elusive?

Quick Summary

The title of the hardest vitamin to get naturally is often debated between Vitamin B12 and Vitamin D, with different populations facing unique challenges in obtaining sufficient amounts from diet and sunlight.

Key Points

Vitamin B12 is hardest for specific diets: Vegans and vegetarians face the biggest challenge, as it is found almost exclusively in animal products.
Vitamin D is most affected by environment: Its synthesis depends heavily on sun exposure, which is influenced by geography, season, and skin tone.
Absorption issues affect B12 intake: Age, GI disorders like Crohn's, and certain medications can prevent the body from properly absorbing B12 from food.
Lifestyle impacts Vitamin D levels: Limited sun exposure due to living in northern latitudes or staying indoors increases the risk of deficiency.
Fortified foods help bridge gaps: For both vitamins, fortified cereals, milk, and plant-based milks offer an alternative source for those with dietary restrictions or insufficient sun exposure.
Professional guidance is key: To properly diagnose and treat deficiencies, it is crucial to consult a healthcare provider, who may recommend supplements or other interventions.

The Case for Vitamin B12

Vitamin B12, crucial for nerve function, DNA synthesis, and red blood cell formation, is primarily found in animal products. This poses a significant challenge for vegans and vegetarians. While some plant-based foods are fortified, relying solely on them requires careful planning.

Challenges with Absorption

Proper B12 absorption requires intrinsic factor, a protein produced in the stomach. Several factors can hinder this process:

Pernicious anemia, an autoimmune condition.
Reduced stomach acid with aging.
Gastrointestinal disorders like Crohn's and celiac disease.
Certain medications, including PPIs and metformin.

The Case for Vitamin D

Vitamin D, essential for bone health and immune function, is mainly synthesized in the skin through sun exposure. This dependence on sunlight creates challenges for many.

Obstacles to Sun Synthesis

Factors affecting Vitamin D production from the sun include:

Geographic location and season.
Time of day.
Skin pigmentation.
Use of sunscreen and protective clothing.
Spending limited time outdoors.

Natural food sources of Vitamin D are scarce, including fatty fish, fish liver oils, egg yolks, and beef liver, along with some fortified foods.

Comparison: Vitamin B12 vs. Vitamin D


Feature	Vitamin B12	Vitamin D
Primary Natural Source	Animal products (meat, dairy, eggs)	Sunlight (UVB rays)
Dietary Sources	Abundant in animal foods; almost non-existent in plants	Very limited in nature; mainly fatty fish and fortified foods
Primary Obstacle	Limited food sources for specific diets and complex absorption process affected by age and health	Dependence on environmental factors (sunlight) and lifestyle choices
At-Risk Groups	Vegans/vegetarians, older adults, people with pernicious anemia or GI disorders	People in northern latitudes, those with darker skin, elderly, indoor workers

Conclusion: So, What is the Hardest Vitamin to Get Naturally?

Determining the hardest vitamin depends on individual circumstances. For vegans and vegetarians, B12 is particularly challenging due to its absence in plant foods. For a broader population, Vitamin D is arguably harder to obtain naturally due to its reliance on variable environmental factors like sunlight. B12 absorption issues also affect many individuals. Both highlight the importance of assessing personal risk and considering supplementation. You can learn more about Vitamin D from the Harvard T.H. Chan School of Public Health(https://nutritionsource.hsph.harvard.edu/vitamin-d/).

The Risks of Deficiency

Deficiencies in both B12 and D carry health risks. B12 deficiency can cause anemia and neurological problems, while Vitamin D deficiency is linked to poor bone health. Maintaining adequate levels is vital for health.

Lifestyle Adjustments

To improve Vitamin D levels naturally, moderate sun exposure and dietary sources like fatty fish can help. Vegans can get B12 from fortified foods or supplements. Those with absorption issues should consult a doctor.

The Role of Fortified Foods

Fortified foods are important for both B12 (especially for vegans) and Vitamin D. However, they may not be sufficient, and understanding individual needs is crucial.

The Importance of Professional Guidance

Consulting a healthcare professional or dietitian is essential before making significant dietary or supplement changes. They can provide personalized advice and arrange testing to check vitamin levels.

Frequently Asked Questions

For vegans, Vitamin B12 is the hardest to get naturally, as it is only found naturally in animal products. Vegans must rely on fortified foods or supplements to meet their B12 needs.

Vitamin D is hard to get naturally because its main source is sun exposure, which is affected by geography, season, time of day, skin tone, and lifestyle factors like spending time indoors.

While a lacto-ovo vegetarian diet includes dairy and eggs, which contain B12, the levels may not be sufficient for everyone. Many vegetarians still have low B12 levels and may need fortified foods or supplements.

Medical conditions that can cause B12 malabsorption include pernicious anemia, atrophic gastritis, Crohn's disease, and celiac disease.

To increase Vitamin D levels naturally, aim for moderate sun exposure during peak seasons and incorporate fatty fish, eggs, and fortified foods into your diet.

For individuals with severe deficiency or malabsorption, B12 injections are often the fastest treatment. High-dose oral supplements can also be effective.

While fortified foods like milk, cereals, and juices contribute to Vitamin D intake, they may not provide enough to compensate for limited sun exposure. Many people require supplements.