Hi Carolina, thank you for the response, looking forward to your more thorough response! 
 

Dear Vasco,
Dear Team of Veganuary,

I want to thank you both for your input/contributions here as I think it is incredibly important to properly verify the actual effectiveness of any possible intervention to help animals. I have followed Veganuary’s success for many year and am a long-time donor, and have previously tried to estimate your actual impact, for example here.

Reasons I am positive about the impact of Veganuary:

I think there are some incredibly promising metrics about Veganuary’s success, for examnple this 2019 survey on why people go Vegan in which 12800 people participated, out of them 369 (a little under 3%) said that Veganuary was the first thing that seriously made them consider going Vegan. If we assume this metric is accurate and still holds true today, and that roughly 1% of the people in Europe and North America are Vegan (or very roughly 10 milllion people out of 1 billion people), as many as 280 000 people might be Vegan today because of Veganuary. If we further assume each Vegan person saves on average one animal’s live a day, that would be 100 000 000 (100 million) animals spared each year due to Veganuary. 
(I know I am making a lot of big assumptions here and some of those number are almost certainly too optimistic, for example an online poll like the one I linked will almost certainly overrepresent a primarily online campaign like Veganaury. I also don’t know how to convert that number to the metric of SAD’s used here)

Reasons I think Veganuary might be less impactful than it used to be:

I also think there are some worrying signs about the success of Veganuary, specifically in the last three years.

1) My biggest reason for this is that the actual search interest in Veganuary is decreasing since 2022, google trends show that there there was only 57% as much search interest in Veganaury in January 2025 as there was in 2020 and 2022 (The two years with the highest search interest):
 

2) My second reason is that the amount of people who sign up to the core of your Veganaury Campaing – the 31 daily Emails – seems to be decreasing:

2022 Here is Veganaury’s 2022 report: https://veganuary.com/wp-content/uploads/2022/03/Veganuary-2022-End-Of-Campaign-Report.pdf where you reported 629 000 people signing up / 19,6 million emails sent (31,16 Emails per signup, so checks out pretty closely with 31 days in January)

2024 Heres the 2024 report: 
https://veganuary.com/wp-content/uploads/2024/03/Campaign-Report-2024-UK.pdf in which you no longer posted a direct amount of people who had signed up by Email, but you sent 17,5 million Emails. Assuming again 31,16 Emails per participant, that is around 560000 signups, a clear decrease from the 700k you reported in 2023. (https://veganuary.com/wp-content/uploads/2023/12/Veganuary-2023-EoC-Report-UK.pdf) – If I am correct here, last year was the first time your campaign significantly decreased compared to the year before in the amount of Email signups. I hope you will once again share the number of Email signups for Veganaury 2025 so we have a better comparison. 

I know you say your campaign has spread to other channels instead of just Email like YouTube, podcasts, etc. - But every single Veganuary website (All individual country campaigns) I visit still asks me only to sign up by Email, so I strongly believe that this is still the core of your campaign and the best indicator of your campaigns actual success. I also believe if your campaign in 2025 was much bigger than 2022 due to people using many other channels compared to just Email, we would see search interest increasing on Google trends instead of decreasing.
 

Suggestions how I think you can better verify your actual impact:

Besides continuing to share the number of Email signups, here are some ways how I think you could increase / confirm the accuracy of the YouGov survey:

1 – Run a similar YouGov Survey about a completely made up campaign similar to Veganaury and see if results are different. For example ask participants if they have participated in „Plantober“ – A challenge for people to eat plant based for the month of October – which does of course not exist, so we would expect that 0% respond that they participated in such a poll if it is accurate. If the number is above 0 but below the YouGov numbers for Veganuary, that might be a good indicator to how much the YouGov survey overestimates participation. If the results are similar to the YouGov poll about Veganaury, we should probably not trust these polls at all anymore. 

2 – Make the poll have 2 parts and do not direcly bring up Veganuary in it. For example:
Question 1 – Have you decreased your consumption of any specific type of product in the month of January?
Question 2 – Asked to anyone who answers „animal products“ / „meat“ or similar in question 1 – What was your primary motivation to do so? And then report the amount of people who say they decreased animal product consumption because of Veganuary. 
This would not only reduce social desirability as a factor since people would have to say what they reduced themselves, but also show what percentage of people who say they did decrease their animal product consumption did so because of Veganuary.

Finally, I want to thank you for the incredible work you are doing and your openness to respond to criticism! I might sound overly negative in my response here, but I am genuinely a great fan and longtime supporter of Veganuary and I do think that Vasco is definitely underestimating your impact. 

Edit: Spelling and small changes for clarity. 

Thanks, yeah this seems like a reasonable approach. Hoping from a statement from ACE or Sinergia.

Thanks, very interesting indeed!