Seasonal changes in autumn and winter affect people both physically and mentally. Days become shorter, the weather turns colder, and the flu season begins. These factors weaken the immune system and make many people feel more tired than usual. To cope with tiredness and reduce vulnerability to infections, the body needs strong nutritional support. Vitamin B12 is one of the key nutrients that helps maintain energy levels and supports immunity during the colder months. Whether obtained from food or from supplements such as tablets, sprays or injections, Vitamin B12 can make a real difference in how the body responds to seasonal challenges.
Seasonal Changes and Their Impact on Energy and Immunity
During autumn and winter, several environmental factors combine to challenge the body’s natural defences. Less exposure to sunlight reduces vitamin D production, which plays a role in immune function and overall vitality. Shorter daylight hours can also disrupt sleep patterns and contribute to seasonal fatigue. Cold weather means people spend more time indoors, making it easier for viruses to circulate and intensifying the flu season in Ireland. For children at school and adults in busy workplaces, these conditions create greater risks of tiredness and frequent infections. Recognising the effect of seasonal changes on immunity highlights why nutrients such as Vitamin B12 are important for staying resilient.
The Role of Vitamin B12 in Supporting Energy Levels
Vitamin B12 plays a central role in the production of red blood cells and the functioning of the nervous system, both of which are essential for maintaining energy. When levels of Vitamin B12 are low, oxygen transport in the body becomes less efficient, and tiredness is one of the first symptoms to appear. Researchers writing in the Journal Nutrients explain that Vitamin B12 contributes to normal energy metabolism by supporting enzymatic reactions involved in the release of energy from food (O’Leary & Samman, 2010).
During autumn and winter, many people experience what is often described as seasonal fatigue. Shorter days and colder weather can intensify feelings of low energy, and insufficient Vitamin B12 may make this worse. According to WebMD, individuals with low Vitamin B12 levels are more likely to experience fatigue, weakness and difficulties with concentration. Adequate intake of Vitamin B12, through food sources or dietary supplements, is therefore an important step in maintaining vitality during the colder months.
Certain groups are at higher risk of low B12 status, including older adults, vegans, vegetarians and people with specific digestive conditions. For these individuals, the combined effect of seasonal changes and inadequate Vitamin B12 can be especially challenging. Choosing reliable sources of Vitamin B12, whether through diet or supplements such as tablets, sprays or methylcobalamin-based products, can help maintain consistent energy levels. Beyond reducing tiredness, supporting Vitamin B12 intake during autumn and winter also prepares the body for the increased risk of cold and flu.
Vitamin B12 and Immunity During the Cold Months
Vitamin B12 is essential not only for energy but also for the immune system. It contributes to the production of red blood cells, which transport oxygen to tissues and support the body’s natural defences. Without sufficient Vitamin B12, these processes become less efficient, and the immune system may be slower to respond to colds and flu.
Research published in Clinical and Experimental Immunology shows that Vitamin B12 is involved in the development and activity of immune cells, including white blood cells. This connection helps explain why low B12 status has been associated with reduced resistance to infections. During autumn and winter, when flu season in Ireland is at its peak, making sure you get enough Vitamin B12 from food or supplements can help support immunity in winter and keep the body more resilient against seasonal challenges.
Sources of Vitamin B12 for Autumn and Winter Wellness
Vitamin B12 is naturally present in a range of animal-based foods. Rich sources of Vitamin B12 include meat, fish, poultry, eggs and dairy products, all of which can contribute to daily intake. For many people, these foods provide enough of the vitamin to maintain energy and immunity during the colder months.
However, those following vegan or vegetarian diets are at greater risk of deficiency, since plant-based foods do not naturally contain Vitamin B12. In autumn and winter, when meal variety may decrease and comfort foods are more common, it can be even harder to meet daily needs without careful planning. Fortified foods such as plant-based milks or breakfast cereals can help, but they may not always provide enough.
For individuals who struggle to reach recommended levels through diet alone, Vitamin B12 dietary supplements are a reliable option. Tablets, sprays and other forms can support consistent intake and ensure that the body receives what it needs to stay resilient through autumn and winter.
Supplements and Practical Options for the Colder Season
When the daily diet does not provide enough Vitamin B12, supplements can play an important role. They offer a reliable way to maintain steady intake throughout the colder months, when tiredness and weaker immunity are more common.
Vitamin B12 supplements are available in different forms, making it easier to choose the option that suits individual needs. B12 tablets provide a convenient choice for daily use, while a B12 spray offers a quick and simple alternative. Some products contain natural methylcobalamin, the active enzyme form of Vitamin B12, which the body retains for longer.
Sona offers a range of options to support different needs. Sona Vitamin B12 Tablets – Methylcobalamin 1000 μg provide higher strength support, while the Sona Vitamin B12 Tablets – Methylcobalamin 500 μg offer a moderate daily dose. For those who prefer a simple alternative, the Sona B12 Oral Spray delivers Vitamin B12 in an easy-to-use oral spray. The best vitamin B12 supplement depends on individual preferences and circumstances. Older adults, vegans, vegetarians and people with certain digestive conditions may all benefit from adding a supplement to their routine. By selecting a format that fits their lifestyle, individuals can support both energy and immunity more consistently during winter.
Checking Your Levels with a B12 Blood Test
Despite eating well, some people may still find their Vitamin B12 levels are not where they should be. Symptoms such as persistent fatigue, weakness, dizziness or poor concentration can sometimes point to a Vitamin B12 deficiency. In certain cases, low B12 status may also contribute to mood changes or tingling sensations in the hands and feet.
A B12 blood test is the most reliable way to confirm whether levels are within the healthy range. Health professionals often recommend testing if symptoms continue or if someone belongs to a higher risk group, such as older adults, vegans or people with digestive conditions that affect nutrient absorption.
During autumn and winter, when tiredness and frequent colds are more common, a blood test can help identify if low Vitamin B12 is playing a role. Detecting a deficiency early means it can be corrected quickly with the right dietary changes or supplements, reducing the risk of longer-term side effects. In rare cases, very high doses of supplements may also cause minor vitamin B12 side effects, which is why medical guidance is recommended.
A B12 blood test is a simple procedure carried out by a healthcare professional, usually involving a small blood sample from the arm. If a deficiency is confirmed, treatment may vary depending on the severity. In mild cases, dietary supplements are often sufficient, while in more significant deficiencies, doctors may recommend Vitamin B12 injections. These are generally prescribed and administered under medical supervision to restore levels more quickly.
Final Thoughts
Seasonal changes in autumn and winter can bring lower energy, weaker immunity and a greater risk of colds and flu. Ensuring that Vitamin B12 levels are maintained is one way to support the body through these challenges. From its role in energy metabolism to its contribution to immune defence, the benefits of Vitamin B12 are well established.
While foods such as fish, meat, dairy and fortified products remain important sources, many people may need extra support from dietary supplements. Options such as tablets, capsules and sprays make it easier to keep levels steady throughout the colder months. By choosing the format that suits individual needs, it is possible to stay energised and support immunity in the colder months. This also helps people feel better prepared for the season ahead.
References;
O’Leary, F. & Samman, S., 2010. Vitamin B12 in health and disease. Nutrients, 2(3), pp.299–316.
WebMD, 2025. Vitamin B12: What to Know. Available at: https://www.webmd.com/diet/vitamin-b12-deficiency-symptoms-causes
Tamura, J., Kubota, K., Murakami, H., et al. (1999). Immunomodulation by vitamin B12: augmentation of CD8+ T lymphocytes and natural killer (NK) cell activity in vitamin B12-deficient patients by methyl-B12 treatment. Clinical and Experimental Immunology, 116(1), pp.28–32.