Veganuary and the importance of supplementation

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Researcher Network member, Dr Elizabeth Eveleigh, discusses the results of her recent research into the effects of short-term vegan diets on nutrient intake


The ‘Veganuary’ pledge is a globally recognised campaign that encourages people to embrace a vegan lifestyle for the month of January1. This initiative has gained considerable popularity with over 500,000 participants worldwide temporarily switching to a vegan diet in 20211. Veganuary may serve as a gateway to veganism for hesitant individuals to make a permanent commitment. During the month of Veganuary, participants may be introduced to vegan food products and substantially change their dietary habits. In some cases, individuals may potentially adopt long-lasting changes in their eating practices.

Motivations for embracing veganism vary2; health improvement is a predominant factor for those not fully committed, while ethical considerations drive permanent vegans. Despite the popularity of short-term veganism campaigns like Veganuary, exploration of motivations in scientific literature remains limited.

While well-planned vegan diets can meet nutritional needs3, nutritional planning is key, balancing the main food groups and making good use of fortified foods and selective supplementation4. As with any diet, there are potential nutritional shortfalls. Notably, vitamins B12, and D, along with minerals iodine, and selenium,  are nutrients deserving attention in vegan diets as they are less abundant in plant foods. Nutrient bioavailability is also an important consideration when it comes to nutritional planning, with food combinations, cooking, and preparation methods playing a key role in optimising absorption5. Fortified products are important for a well-balanced vegan diet. Some vegan foods, like dairy-free alternatives, have added vitamins B12, D, calcium, and iodine. However, not all brands fortify their products, and the level of fortification can differ within the same type of item. For example, fresh dairy-free options may be fortified, but UHT versions might not be6,7. Therefore, the intake of micronutrients may be influenced by the availability and choice of fortified products. The ability to plan diets effectively during temporary changes is uncertain, but enhanced nutrient knowledge may improve individuals' adaptability and food selection in such transitions.

As the popularity of these campaigns continues to grow, we were keen to understand the effects of short-term vegan diets on nutrient intake, micronutrient knowledge, and motivations for embracing a vegan lifestyle. To do this we aimed to evaluate the impact of 4-week vegan diet during Veganuary in a diverse group of UK adults aged 18–60.


Our study involved 154 participants, comprising vegetarians and omnivores committed to a 4-week vegan diet during Veganuary. Additionally, control groups were established, consisting of vegans and omnivores who did not transition to a vegan diet. We collected data before and after Veganuary in the years 2019 and 2020, employing Food Frequency Questionnaires (FFQs) to estimate dietary intake. In 2019, a comprehensive assessment of all micronutrients was conducted, while in 2020, the survey was streamlined to specifically focus on evaluating iodine intake, aiming to alleviate the burden amid the COVID-19 pandemic. While micronutrient knowledge and motivation were assessed through comprehensive questionnaires.


Our study revealed significant changes in nutrient intake among omnivores who adopted a short-term vegan diet as part of Veganuary. Notably, there was a decrease in the intake of iodine, B12, cholesterol, and saturated fatty acids (SFAs) before supplements were added to the analysis. While these reductions might align with the goals of a vegan diet (i.e., as a tool for weight loss), it raises concerns about potential nutrient deficiencies if veganism is continued into the longer-term, especially given the limited duration of the dietary shift. Our results also indicate that supplements could mitigate the impact of low dietary intake. For instance, before supplement inclusion, B12 intake was notably lower in vegans and vegetarians, with omnivores transitioning to a vegan diet experiencing a significant reduction. However, with the inclusion of supplements, B12 intake substantially improved in both vegan and omnivore groups.

Micronutrient knowledge emerged as a key area of concern, with participants demonstrating low levels of awareness about essential vitamins and minerals in foods in general. Participants demonstrated improved knowledge and awareness of vitamins B12 and D. This heightened awareness likely motivated individuals to choose supplements for these specific nutrients during their short-term engagement with veganism, potentially preventing declines in intake. Micronutrient knowledge gaps highlight the importance of educational initiatives to equip individuals with the information needed to maintain a balanced vegan diet during Veganuary.

Motivations for veganism varied within the participant groups. In both years, we found that vegetarians were motivated to try veganism by concerns about factory farming and animal welfare. Health was the primary motivator for omnivores in 2019, but in 2020, there was a notable shift towards prioritising climate and sustainability. Further research is warranted to explore how these motivations impact dietary patterns, potentially shaping the success and sustainability of vegan pledges.

Implications and Recommendations

The findings underscore the importance of providing nutritional guidance or supplementation for individuals undertaking short-term vegan diets such as during Veganuary. While the campaign serves as a possible entry point into veganism, ensuring the health and well-being of participants should be a priority.

Attention to UK micronutrient intake and knowledge is crucial for the promotion of sustainable and health-conscious vegan lifestyles. Researchers, health professionals, and campaign organisers can collaborate to develop targeted interventions that address knowledge gaps and support individuals in making informed dietary choices.


As global interest in veganism continues to rise, studies like ours contribute valuable insights into the short-term effects of vegan diets. However comprehensive studies are needed to evaluate the health impact of short-term veganism and to ensure that participants receive adequate support for nutritional changes.

If you are interested in finding out more, please read our published research article here:


1. Veganuary. Veganuary 2023. 2023. Available online: (accessed on 24 August 2022).

2. Fox, N.; Ward, K. Health, ethics and environment: A qualitative study of vegetarian motivations. Appetite. 2008, 50, 422–429

3. British Dietetic Association (BDA). British Dietetic Association Confirms Well-Planned Vegan Diets Can Support Healthy Living in People of All Ages. 2017. Available online: (accessed on 26 August 2022).

4. Neufingerl, N., & Eilander, A. Nutrient Intake and Status in Adults Consuming Plant-Based Diets Compared to Meat-Eaters: A Systematic Review. Nutrients. 2021, 14(1).

5. Platel, K.; Srinivasan, K. Bioavailability of Micronutrients from Plant Foods: An Update. Crit. Rev. Food Sci. Nutr. 2016, 56, 1608–1619.

6. Nicol, K.; Thomas, E.L.; Nugent, A.P.; Woodside, J.V.; Hart, K.H.; Bath, S.C. Iodine fortification of plant-based dairy and fish alternatives: The effect of substitution on iodine intake based on a market survey in the UK. Br. J. Nutr. 2023, 129, 832–842.

7. Alcorta, A.; Porta, A.; Tárrega, A.; Alvarez, M.D.; Vaquero, M.P. Foods for Plant-Based Diets: Challenges and Innovations. Foods. 2021, 10, 293.

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