Environmental impacts of nutritional supplements

People eating a vegan diet are usually advised to take certain nutritional supplements, such as Vitamin B12. I am curious as to what the environmental impact is of obtaining micronutrients through supplements as opposed to food. A search for life cycle assessment of vitamins, minerals or nutritional supplements returns only a few results:

Do you know of any other relevant resources? Has anyone compared the impacts of obtaining particular nutrients from supplements versus from foods? Is it even possible to compare the two sources directly, since foods supply so many different nutrients at once?


This is something I have thought about before. I’ve always been a bit sceptical of the widespread taking of vitamins/supplements without particular (e.g. medical) cause and including nutrients that should be readily available from a normal diet for most people (e.g. vitamin C), partly on grounds of assumed environmental impacts of their production. So when I adopted a largely plant-based diet myself (primarily for environmental reasons) and found it necessary to rely on supplements/fortified foodstuffs for certain micronutrients, I began wondering quite what those impacts might be and how they compare to those of “natural” food sources.

So I fancied taking this on as a pet research project, but… confess I have not made much headway. Focussing on vitamin B12 for the time being, I’ve learned some general stuff about its production that offers vague impressions about relative sustainability (compared to other vitamins/production processes), but have not found any more concrete quantitative data that would enable direct comparisons with food sources. B12 is apparently one of the few vitamins to be produced primarily through biotechnological processes (microbial fermentation); this is generally lower-impact than chemical synthesis (which is not commercially viable in the case of B12 but is used for most B vitamins) as the latter often uses non-renewable resources and produces hazardous waste. However, downstream processing of the microbial products (conversion to the stable form cyanocobalamin) is considerably higher-impact. I would also point out that the authors of the main paper I am drawing on here (Acevedo-Rocha et al. 2019) have filed patents relating to B-vitamin fermentation processes so obviously had an interest in portraying these as the more sustainable option.

Berstenhorst et al. (2009) note that approx. 50% of industrially-produced vitamins go into animal feed. Therefore, supposing industrial production of vitamins does have significant environmental costs, perhaps these could be reduced through lower consumption of animal products. Counter-intuitive given the starting point of this discussion (the need for supplements/fortified foods in vegan diets), and echoes that old argument about vegans being responsible for destroying rainforests with all that soya they eat (when in fact vastly more goes into animal feed). Presumably if a “natural” food source of a given vitamin is animal-based (which basically all reliable B12 sources are), and if the animal from which it comes has been fed synthetic vitamin supplements, then taking the supplement directly cannot be any higher impact than opting for the “natural” source. The limitation here is not knowing how widespread the supplementation of specific vitamins is in livestock farming – could undermine this whole line of thought. To come back to B12 specifically, I know ruminants are able to access B12 produced by their own gut bacteria and think(?) vitamin supplementation is more common in intensive farming systems, so perhaps (as is often the case) we need to differentiate here between production methods (specifically how the animals have been fed) rather than just product types (“animal products”).

On learning that human waste is rich in B12 (apparently we have the right bacteria to synthesise it, but in the wrong place – they are found in the colon, so the resulting B12 is excreted rather than absorbed) I couldn’t help wondering whether it would be at all hypothetically possible to extract & purify it (obvious issues here around (a) safety and (b) squeamishness)… I found no literature on quite this subject, but did come across a study (Kumari et al. 2021) in which lactobacilli with extracellular B12 synthesising capabilities were extracted from human faecal samples and used for biofortification of soy milk with B12 via fermentation… environmental impacts are not discussed but direct fermentation of the food product suggests an interesting potential alternative to conventional B12 fortification processes…


Acevedo-Rocha et al. (2019): Microbial cell factories for the sustainable manufacturing of B vitamins - ScienceDirect

Berstenhorst et al. (2009): Vitamins and Vitamin-like Compounds: Microbial Production - ScienceDirect

Kumari et al. (2021): Vitamin B12 biofortification of soymilk through optimized fermentation with extracellular B12 producing Lactobacillus isolates of human fecal origin - ScienceDirect

1 Like

This is fascinating. I had no idea, and it changes the way I think about vitamin supplements!

As you say, not knowing the extent of livestock vitamin supplementation is an issue. I initially wondered whether a 50-50 split between human and livestock vitamin use would actually indicate a low prevalence of vitamin use in livestock farming, because I assumed that only a tiny percentage of people take vitamins (e.g. due to being on a vegan diet).

However, my assumption appears to be wrong, at least in some countries: this page suggests 86% of Americans take vitamins or supplements; this source suggests 58% of American adults used dietary supplements in the last month; this source suggests 65% of UK adults took a supplement in the year running up to the survey.

So perhaps a shift to lower meat consumption could actually lower overall vitamin use, if it is common in livestock rearing.

The framing that:

reminds me that when I started taking algae-based omega-3 supplements, I was surprised to notice that they had an almost fishy taste. I then realised after some googling that fish - usually framed as a good source of the EPA/DHA form of omega-3 - do not in fact synthesise EPA/DHA themselves, but get it from the algae they consume. So it possibly makes more sense to say that fish taste of algae, than to say that the algae-based supplements taste of fish (I’m happy to be corrected by any food scientists reading this!).

Of course, there are issues such as cost associated with the supplements - and it’s not as if the fish themselves are eating synthetic omega-3 supplements (unless farmed fish do). I’d like to know what the relative environmental impacts are of fish and bivalves vs these supplements.

Your mention of lactobacilli made me think of lacto-fermentation - the process used to make kimchi, among other products, that uses Lactobacillus bacteria. As you may well know, it’s a traditional process that has supposedly been used for thousands of years, and it’s really easy to do at home (I use this recipe for vegan kimchi, in case you’re interested!).

A quick search for information on whether lacto-fermented foods provide nutritionally significant amounts of B12 turns up mixed evidence:

The picture seems very unclear, and I’m happy to take a supplement to be certain of getting the right amount of B12.

1 Like

The prevalence of vitamin-taking does disturb me a little – I feel like people are easy prey to marketing for supplements (“buy this, it will make you healthy and long-lived”). Though I don’t want to sound patronising/judgemental here and acknowledge that many people have good reasons for taking them.

I too did a bit of googling about algal omega-3 supplements when I was considering taking them, and learned about algae being the original source of fish-based omega-3. I got into a bit of a quagmire trying to unpick the relative environmental impacts, though – a lot of the material I found was obviously heavily biased, by which I mean it was on websites that were trying to sell me either fish-based or algae-based omega-3 supplements! Though it’s a while since I looked into this, and had minimal access to academic journals at the time so was just googling. Might be worth returning to now that I have access to better resources. The issue is further complicated by lack of consensus on health benefits/importance of omega-3s generally and whether ALA (available from plant-based diet) is sufficient or whether a direct source of EPA/DHA (no vegan food sources, but can be produced in the body from ALA) is advisable. I’m glad you raised the issue of cost. I’m lucky enough to be able to afford algal omega-3 supplements at the moment, but very aware that they’re an awful lot more expensive than sardines…

I am not very familiar with kimchi and my previous efforts at fermenting things in jars have not been very successful (ahem), but I’ve had a look at that recipe and think I might summon up the courage to give it a go! In my earlier research on B12 I did come across various claims of plant-based food sources (e.g. tempeh) but the general consensus seemed to be that they only contain low and/or unreliable amounts. The unreliability makes sense to me particularly with regard to fermented foods which use indigenous microbes (as I think is the case with kimchi) rather than adding specific strains – I think not all lactobacilli produce B12 (?) and even if they do there might be a considerable variation between different strains in terms of how much. This page collates evidence relating to alleged plant-based food sources of B12:

Vitamin B12 in Plant Foods – Vegan Health
(Part of a very comprehensive guide on B12 generally in relation to vegan diets: Vitamin B12 – Vegan Health)

The studies they cite relating to Lactobacillus did show some effect in terms of reducing B12 deficiency, but they conclude that there is insufficient evidence to make it a reliable source. This is in line with their general conclusion that although there are some promising options for further research, it would not be wise to rely on any of these as one’s sole source of B12 at present.
So like you, Helen, I am also opting for the supplement. Although I would also like to point out as a (flippant) aside that B12 is one of many reasons to love marmite :wink:

A few other thoughts I’ve had since my previous post:

Organic certification (at least under UK Soil Association standards; other schemes may vary) basically prohibits fortification of foods beyond what is required by law. I personally think a little more leeway here could be useful. I imagine that quite a lot of people who eat vegan for environmental reasons are also drawn to organic foods (for similar reasons) and the lack of fortification of organic foods could therefore compound the difficulties of achieving a healthy vegan diet. Also if these hypothetical organic-leaning vegan consumers are then having to rely more heavily on supplements, could this be higher impact than obtaining (some of) the same micronutrients through fortified foods – just in terms of the extra resources etc. that go into producing & distributing a whole separate product as opposed to fortifying an existing one? Although the differences here are quite possibly minimal (as proportion of whole supply chain impacts) – maybe I am nit-picking. And it’s questionable whether increased fortification would lead to reduction in supplement-taking anyway.

Also wonder about biofortification (enhancing nutritional value of crops via agronomic interventions/breeding/biotech). Could this be a way of reducing the need for supplements, and therefore also whatever environmental impacts are associated with them? I do have some reservations about biofortification more generally (important not to regard it as a “silver bullet” solution and/or an alternative to ensuring that people have access to diverse & healthy diets, particularly in developing countries) but think it definitely worth investigating.

1 Like

Briefly, re B12, this 2020 article (doi:10.1002/14356007.t27_t03) says that “The feed sector accounts for ca. 30% of vitamin B12 sales” - but that’s just for “the pure substance” = cyanocobalamin. The authors also confirm that “Ruminants cover their requirements via the formation of B12 by rumen bacteria, but cobalt supplementation is required”. So in the case of ruminant livestock, B12 supplementation is given mostly in the form of cobalt. I don’t know whether there is any record of sales of cobalt, but there are plenty of mentions of it as a supplement, so for instance for the UK: https://www.gshepherdanimalhealth.co.uk/discovery-centre/cobalt-deficiency and Importance of Cobalt to Beef & Dairy Cattle | Agri-King, etc.

1 Like