Advice, All About Me, Biology

Not Making That Mistake Again: A Quick Dive Into Vegetarian Nutrition

[Content Note: Discussion of diet]

The first time I tried vegetarianism, I ended up deficient in B12. Since then, I’ve realized just how bad vitamin B12 deficiency is (hint: it can cause irreversible neural damage) and resolved to get it right this time.

I’m currently eating no meat, very little milk, almost no eggs, and a fair amount of cheese. I consider clams, oysters, and mussels to be morally (if not taxonomically) vegetables, but am too lazy to eat them regularly. To figure out what this diet put me at risk for, I trolled PubMed [1] until I found a recent article arguing for a vegan diet, then independently checked their nutritional recommendations.

Based on this, I’ve made a number of changes to my diet. I now take two vitamins in the morning and a slew of supplements in sugar-free fruit juice when I get home from work [2]. I hope the combined effect of this will be to protect me from any nutritional problems.

Pictured: the slew. Next: The science!

Once I went to all the work of collecting information and reading through paper abstracts, I realized that other people the same situation might find this research helpful. I’ve chosen to present everything as my diet, not my recommendations. This is what is currently working for me, not necessarily what is “correct” or what would work for anyone else. Diet is very personal and I’m no expert, so I’ve taken great pains to avoid the word “should” here.

That caveat out of the way, let’s get into the details!


Eating cheese gives a relatively easy (and low suffering) source of complete protein, but I didn’t want all of my protein to come from cheese. Therefore, it was heartening to find there are many easy ways to get complete protein from plants. These include combinations (like hummus + pitas or rice + beans) or quinoa.

I try to make some of my lunches revolve around these sources, rather than just cheese.

I’ve decided to supplement my protein intake with protein powder, because I found it hard to get enough protein (I’m aiming for 1g/kg daily, to be on the safe side, estimates of the minimum daily requirements range from at least 0.83g/kg/d to 0.93kg/day and I’m rather more active than the average North American, especially in the summer) with my limited appetite even when I was eating meat. I first tried whey, but found this incredibly hard on my stomach, so I’ve shifted to an unflavoured multiple source vegetable protein that I find not at all unpleasant when mixed with fruit juice.


It seems to be kind of hard to become iron deficient; the closer anyone gets to deficiency, the more effective their body becomes at pulling in iron and holding onto what it already has. This is good for vegetarians, because iron from plants is generally not very bioavailable and it’s harder to get iron when consuming significant calcium at the same time (e.g. a spinach salad with cheese or tofu isn’t that great a source of iron, until your body gets desperate for it).

Even better than this is the fact that iron is one of the rare things that is actually subject to “one weird trick”, namely, iron absorption is greatly aided by vitamin C, even in the presence of calcium. I expect to meet my iron needs via a combination of leafy greens salads + orange slices, protein powder + fruit juice, and oatmeal.

Vitamin B12

As far as I can tell, my diet doesn’t include adequate B12 on its own, so I’m supplementing with 1000mcg sublingually each morning. If I did more of my own cooking, I’d consider nutritional yeast grown in B12 rich media, which seem to be effective in small scale trials and anecdotally among people I know. I can’t figure out if probiotics work or not; the study above says no. Another study I found said yes, but they were giving out the probiotics in yoghurt, which is naturally a good source of vitamin B12. This baffling decision makes me consider the study hopelessly confounded and has me overall pessimistic about probiotics.

I was frightened when I learned that folic acid fortification is very effective at preventing B12 deficiency driven anemia, but not effective against B12 deficiency driven neural damage (so the neural damage can sneak up with no warning). The NIH recommends keeping folic acid consumption below 1g/day, which can be difficult to do when many fortified foods contain much more folic acid than they claim to. If I was eating more breads or cereals I’d be worried about this. For now, I’m just filing it away as a thing to remember; if I ever start eating more bread and cereal, I’m going to want to be very careful to ensure I’m consuming enough B12.

I take B12 especially seriously because I take proton pump inhibitors, which have been associated with an increased risk of B12 deficiency.


Calcium is a mess.

Here are studies I’ve found about calcium:

One explanation for this is that the meta-analysis that finds no significant relationship between fracture risk and calcium intake didn’t find anyone with calcium levels low enough to observe significant effects. That would mean that the study that found vegans broke bones more often found the effect because the vegans they studied were so low on calcium.

Except that study is barely significant (the relative risk lower bound includes 1.02). Barely significant study + meta-analysis that turns up nothing points pretty strongly at “this was only significant because of P-hacking”.

Since yoghurt is apparently an ideal protein source for cycling recovery and three small containers of yoghurt provides an ideal amount of protein for cycling recovery (and Walmart gives a deal if you buy three cases of 4 of these, which makes it cheap to mix and match flavours), I will probably continue to have significant amounts of yoghurt (and therefore lots of extra calcium) whenever I’m cycling. This will make me feel a bit better about my mountain biking related fracture risk. Otherwise, I’m not going to worry about calcium intake (remember: I am eating plenty of cheese).

I am glad I looked into calcium though, because I found something really cool: Chinese vegetables (like Bok Choi, Chinese cabbage flower leaves, Chinese mustard greens, and Chinese spinach) provide calcium that is much more bioavailable than many western vegetables. I wonder if this is related to prevalence of milk drinking across cultures?

Vitamin D

Vitamin D is important for increasing absorption of calcium. Since Vitamin D is synthesized in the skin in response to light and I live in Canada, I’m pretty likely to be deficient in it, at least in the winter (something like 1 in 35 Canadians are). There was a story going around that the government wouldn’t pay for most vitamin D testing because Canadians are assumed to be deficient in it, but according to the Toronto Star article above, the real reason is that so many charlatans have claimed it can do everything under the sun that demand for tests was becoming a wasteful drain on funds.

My plan is to take a D3 supplement in the months where I don’t regularly wear shorts and a t-shirt. Given that I cycle to work and frequently walk around town, I expect to get more than enough D3 when my skin is actually being exposed to sunlight.

Omega-3 Fatty Acids

From what I read, the absolute level of these is less important that the ratio of Omega-3 fatty acids to Omega-6 fatty acids. An ideal ratio is close to 1:1. The average westerner has a ratio closer to 16:1. While it is clear that this isn’t just a vegetarian problem, it seems like omnivores who eat a lot of fish have a healthier ratio. Given that a good ratio is associated with pretty much every good thing under the sun (is this why Japan has such high life expectancies?), I’m pretty motivated to get my ratio to the sweet spot.

As far as I could tell, there was once controversy as to whether non-animal sources of Omega-3 fatty acids could be adequate, but that looks to be cleared up in favour of the vegetarian sources. This is good, because it means that I can follow the recommendations in this paper and consume about 6g of unheated flaxseed oil daily to meet my Omega-3 needs. This goes pretty easily into my fruit juice mixture with my protein powder and creatine.


There’s some evidence (although no meta-analyses that I could find) that creatine improves cognitive performance in vegetarians (although not in omnivores, probably because it is present in meat [3]). I’ve decided to take 5g a day because it seems to be largely risk free and it also makes exercise feel somewhat easier.

That’s everything I was able to dig up in a few hours of research. If I’ve made any horrible mistakes, I’d very much like to hear about them.


[1] I like PubMed because it doesn’t index journals unless they meet certain standards of quality. This doesn’t ensure anything, but it does mean I don’t have to constantly check the impact factor and editorial board of anything I read. ^

[2] The timing is based on convenience, not science. The fruit juice is actually important, because the vitamin C in it makes the iron in my protein powder more bio-available. It also makes the whole mixture palatable, which is what I originally chose it for. ^

[3] Although people I know have also speculated that this might just be the effect of poor diet. That is to say, if you’re studying university vegetarians, you might be primarily studying people who recently adopted vegetarianism and (like I was the first time I tried it) are deficient in a few important things because they’re restricting what already tends to be a somewhat poor student diet. A definitive mechanism will probably have to wait for many more studies. ^

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