Which vitamin is difficult to get? A look at D and B12 challenges

December 31, 2025 •

4 min read

According to the NIH, approximately one billion people worldwide are estimated to have a vitamin D deficiency, making it one of the most difficult vitamins to get. However, other factors like diet and age make certain vitamins, particularly B12, uniquely challenging to acquire.

Quick Summary

This article explores the vitamins most challenging to obtain, focusing on the unique difficulties with vitamin D synthesis and vitamin B12 absorption for certain populations, offering solutions.

Key Points

Vitamin D Synthesis: Your body's ability to produce Vitamin D from sunlight is affected by latitude, season, skin pigmentation, and age, making it a challenge for many.
Limited Food Sources: Few foods naturally contain high amounts of Vitamin D, with fortified products often being the primary dietary source.
B12 Absorption Issues: Vitamin B12 deficiency is often linked to malabsorption problems, especially in older adults and those with certain medical conditions, rather than purely dietary intake.
Vegan Diet Concerns: Vegans and vegetarians are at high risk for Vitamin B12 deficiency since it is not naturally found in plant foods.
Supplementation Necessity: For both vitamins D and B12, supplements are a necessary and recommended strategy for high-risk individuals when dietary or lifestyle changes are insufficient.
Age-Related Risk: Older adults are at increased risk for deficiencies in both vitamins D and B12 due to lower skin synthesis and compromised absorption.

The Vitamin Dilemma: Why Some Nutrients Are Hard to Get

While a balanced diet is crucial for health, certain vitamins present unique hurdles for the body to acquire, either through dietary sources or natural processes. This article focuses on two vitamins, D and B12, which are famously difficult to obtain and maintain in adequate levels for many people. Understanding these challenges is the first step toward overcoming them through informed lifestyle and diet choices.

The Case for Vitamin D: The Sunshine Vitamin Dilemma

Vitamin D is often called the "sunshine vitamin" because the body primarily produces it in the skin in response to sunlight. However, this natural production process is far from reliable for most people due to a variety of factors:

Limited sun exposure: For people living in northern latitudes, winter months offer insufficient UVB radiation for vitamin D synthesis. Similarly, those who spend most of their time indoors receive no benefit.
Skin pigmentation: The amount of melanin in the skin acts as a natural sunblock. People with darker skin tones require significantly more sun exposure than those with lighter skin to produce the same amount of vitamin D, increasing their risk of deficiency.
Sunscreen use: While essential for preventing skin cancer, sunscreen with an SPF of 8 or higher effectively blocks the UVB rays needed for vitamin D production.
Few natural food sources: Unlike many vitamins, vitamin D is not abundant in a wide variety of foods. Natural dietary sources are limited to fatty fish, fish liver oils, egg yolks, and certain mushrooms.
Fortified foods vary: Many common foods like milk, orange juice, and cereal are fortified with vitamin D. However, the amount varies by product and brand, and these sources alone are often insufficient to meet daily needs.

Vitamin B12: The Absorption and Dietary Challenge

Vitamin B12 is essential for nerve function, red blood cell formation, and DNA synthesis. Its difficulty lies not just in its sources but in its complex absorption process, which can be impaired by several factors, even when intake is adequate:

Animal product dependence: B12 is found almost exclusively in animal products like meat, fish, poultry, eggs, and dairy. This makes maintaining adequate intake a significant challenge for vegans and strict vegetarians who must rely on supplements or fortified foods.
Intrinsic factor issues: B12 absorption requires a protein called intrinsic factor, produced in the stomach. Conditions like pernicious anemia, an autoimmune disease that prevents intrinsic factor production, cause severe malabsorption.
Age-related decline: As people age, stomach acid production can decrease, which also impairs the release and absorption of B12 from food. This makes older adults a high-risk group for deficiency.
Gastrointestinal surgery: Procedures such as gastric bypass surgery, which reduce the size of the stomach or bypass parts of the small intestine, dramatically impair B12 absorption.

Other Nutritional Hurdles

While Vitamin D and B12 are the most prominent examples of difficult-to-obtain vitamins, other nutrients can also pose problems under specific circumstances:

Vitamin K: Though rare in healthy adults, deficiency can occur with conditions that cause fat malabsorption, since Vitamin K is fat-soluble. It is also a concern for newborns, who are given a standard injection to prevent deficiency bleeding.
Folate: While found in many plant foods, certain populations, such as pregnant women, have a higher requirement that is often not met by diet alone, necessitating supplementation.

Comparison Table: Difficult-to-Obtain Vitamins


Feature	Vitamin D	Vitamin B12
Primary Source	Sunlight exposure on skin	Animal-based foods (meat, dairy, eggs)
Natural Food Sources	Very few (fatty fish, cod liver oil)	Exclusively animal products (requires fortification for plants)
Main Challenge	Inconsistent sun exposure due to season, location, and skin tone	Complex absorption process and dietary restrictions (veganism)
Absorption Issues	Fat malabsorption conditions	Lack of intrinsic factor, reduced stomach acid (age-related), surgery
At-Risk Populations	Older adults, dark skin, limited sun exposure, obese individuals	Older adults, vegans/vegetarians, post-gastric surgery patients
Common Solution	Supplementation (especially in winter) and safe sun exposure	Supplements, fortified foods, or injections

Strategies for Ensuring Adequate Vitamin Intake

For those at risk of vitamin D or B12 deficiency, several proactive steps can be taken to ensure adequate intake:

Get safe sun exposure: For vitamin D, aim for a few minutes of unprotected sun exposure on your face, arms, and legs around midday during warmer months, but balance this with sun safety.
Prioritize key food sources: Incorporate fatty fish, eggs, and fortified dairy or plant-based milks into your diet. Vegans should regularly consume fortified cereals, plant-based milks, and nutritional yeast for B12.
Consider supplementation: A supplement is a reliable way to get enough of these vitamins, especially for at-risk groups. Vitamin D3 is often recommended as it may be more effective than D2. For B12, oral supplements or injections may be necessary.
Discuss with a healthcare provider: If you suspect a deficiency, a simple blood test can determine your levels. A doctor can help determine the right dose for supplements based on your needs and health history.

Conclusion: Proactive Steps for Nutritional Health

Identifying which vitamin is difficult to get and why is a crucial step for managing your health. For most, this means paying special attention to vitamin D and vitamin B12. While nature provides the building blocks, modern lifestyles, genetics, and dietary choices can create significant barriers. By being mindful of your diet, balancing sun exposure safely, and considering targeted supplementation, you can effectively counteract the challenges and ensure your body receives these vital nutrients. Consult a healthcare professional to determine if you are at risk and develop a personalized strategy.

For more detailed information on vitamin D, you can refer to the National Institutes of Health Office of Dietary Supplements website.

Frequently Asked Questions

Vitamin D is hard to get because its primary source is sunlight, which is inconsistent due to seasonal changes, geographical location, and skin pigmentation. Furthermore, few foods naturally contain significant amounts, making dietary intake challenging without fortified products.

Those most at risk for vitamin B12 deficiency include older adults (who have reduced absorption), vegans and vegetarians (who avoid animal products), and individuals with medical conditions affecting absorption, such as celiac disease or pernicious anemia.

While fortified foods like milk, cereals, and orange juice contribute to vitamin D intake, they are often not sufficient to meet daily needs, especially for those with risk factors like limited sun exposure or darker skin. Checking nutrition labels is essential.

You can get some vitamin D from safe sun exposure, but balancing this with skin cancer prevention is critical. Healthcare professionals recommend limiting unprotected exposure to brief periods and using sunscreen with an SPF of 15 or more when spending extended time outside.

There are virtually no natural, reliable plant-based sources of vitamin B12. Vegans and vegetarians must consume fortified foods, like fortified cereals and nutritional yeast, or take supplements to meet their needs.

Common symptoms of a B12 deficiency can include fatigue, weakness, numbness or tingling in the hands and feet, memory problems, and a general sense of not feeling well.

The most accurate way to check your vitamin D levels is through a blood test that measures the amount of 25-hydroxyvitamin D in your blood. Your doctor can order this test if they suspect a deficiency.