A vegan diet takes more work to cover the nutrients a body needs. Several are harder to absorb from plants than from animal foods, and B12 is not available from plants at all. This page is the short list: what to check, and what to do about what you find.
If you still eat dairy and eggs, those are supplying B12 and iodine, so you can worry much less about both. If you eat neither, they are the ones to pay attention to. Iron, omega-3 and creatine apply either way, because dairy and eggs do not supply useful amounts of any of them.
Four things are worth measuring. One is worth taking whether you test or not. And one is not a blood test at all: it is what kind of salt is in your cupboard.
Last updated September 8, 2026
The one that is not optional. Bacteria make B12 and animals store it in their tissues, which is why it reaches us through meat, dairy and eggs and not through plants. A supplement is that same bacterial source with the animal left out. A long deficiency causes nerve damage that does not fully reverse [1], so test it, and read the section below before you trust the number.
Usually high on this diet. High folate corrects the anemia of B12 deficiency while the nerve damage carries on underneath [2], so a normal blood count is not reassurance if your folate is plentiful and your B12 is not.
The form of iron in plants is harder to absorb than the iron found in meat, so stores can run low. Low iron does eventually show up in a simple blood count, but ferritin shows it earlier [3], which is why it is worth checking on its own. Most relevant if you menstruate, since you are losing iron every month as well as absorbing less of it.
The second read on iron, and worth pairing with ferritin because ferritin rises with any inflammation and can look adequate when it is not.
Not a vegan problem specifically, since it is hard to get from food on any diet. Your skin makes it from sunlight, which is the free route and the better one in summer: regular time outdoors with arms and legs uncovered, no burning required. Latitude, season, skin tone, age and sunscreen all cut how much you make, which is why so many people run low through winter whatever they eat. If you supplement, D3 from lichen is the vegan form and D2 works less well. Momentous make one at 2,000 IU; note their 5,000 IU is lanolin-derived and is not vegan.
Measures the EPA and DHA in your red cells [4]. Most of what you eat on this diet is ALA, the omega-3 in flax, chia and walnuts, and only a small fraction of it converts into the EPA and DHA your body actually uses. That is why eating flax daily does not settle the question, and why an algae oil supplies them directly instead.
A complete read of the thyroid, paired with the most common non-thyroid causes of the very same symptoms. When you are tired, foggy, or cold, this panel separates a thyroid problem from being low on iron or B vitamins, which feels identical.
A closer fit than the name suggests. It carries B12 and folate together, plus ferritin and the iron workup, which is four of the six tests below. It also runs a full thyroid panel, and that matters more here than it would on most pages: iodine is the gap this diet most often leaves, and the thyroid is what iodine is for. Vitamin D and the Omega-3 Index are add-ons to it, as is MMA, the B12 tie-breaker described below. If the thyroid is not a question for you, ordering the six on their own is cheaper.
Want a different mix? Browse the full library, or tell us what you have noticed if you are not sure where to start.
A serum B12 measures all the B12 in your blood, including a large fraction bound to a protein that cannot deliver it to your cells. So the number can come back normal while the B12 that counts is short.
If your B12 comes back in the lower half of the range and you feel fine, that is usually fine. If it comes back lowish and you have symptoms, or you have been vegan for years without supplementing, the tie-breaker is MMA, a substance that accumulates when B12 is genuinely missing from the reaction it is needed for [5]. It is not cheap and it is not a first test. It is the test that settles an unclear one.
What a deficiency looks like is worth knowing, because the early signs are not where most people look. The mouth tends to show it first: a smooth, sore or unusually red tongue, cracks at the corners of the mouth, mouth ulcers that keep coming back. Paleness and tiredness are common but tell you nothing on their own. Tingling or numbness in the hands or feet means it has reached the nerves, and that is the point at which waiting stops being reasonable. There is no food craving that signals it, whatever you have read.
Only worth ordering if your B12 came back borderline and you have symptoms, or you have eaten this way for years without supplementing. It is the most expensive test on this page and most people never need it.
We earn a commission if you order through this link.
The practical shortcut: supplement B12 regardless of what your level says. It is cheap, taking more than you need does no harm because the excess is passed in urine, and a long deficiency causes damage that cannot be completely undone. Testing then tells you whether what you are taking is working, which is a better question than whether you need it.
Iodine is the one worth knowing about, because it is missing from almost every vegan supplement stack and from almost every list of tests like this one.
In the United States the iodine in most diets comes from dairy, eggs and iodized salt. A vegan diet removes the first two, and then the shift to sea salt, Himalayan salt and kosher salt removes the third without anyone noticing, because none of those are iodized. Measuring urinary iodine in Boston-area vegans found a median of 78 micrograms per litre, under the 100 the World Health Organization treats as sufficient. Vegetarians who still ate dairy and eggs came in at 147, comfortably clear [6]. So this is a vegan question rather than a plant-based one, and if eggs and cheese are still on your plate you can skip the rest of this section.
Overt thyroid problems were uncommon in that group, so this is a shortage rather than a crisis. And the fix costs nothing: use iodized salt for cooking. Keep the fancy salt for the table if you like it, since what matters is that some of your salt is iodized.
Seaweed is the other route, and for populations who eat it regularly it works well. The difficulty is predictability rather than safety: iodine content varies widely between species and between batches, so it is hard to know what a given packet is giving you. If seaweed is already part of how you eat, you are probably covered. If it is not, iodized salt will cover it.
The cholesterol markers on a baseline panel tend to look good on this diet, and that is a real effect rather than a coincidence. If you have moved to eating this way, a lipid panel is one of the places you are most likely to see it.
What the diet does not touch is anything inherited. Lp(a) is set by your genes, does not respond to what you eat, and about one adult in four or five carries a raised level [7]. Eating well does not exempt you from it, and it is measured once in your life. If you are ordering a baseline anyway, add it.
Once in your life, and then never again.
We earn a commission if you order through this link.
The same applies to the whole category of thing a diet cannot reach. A good diet lowers some risks a lot and others not at all, and knowing which is which is more useful than assuming it covers everything.
Creatine comes almost entirely from meat and fish, so this diet supplies very little of it and muscle stores sit lower as a result. That turns out to matter. Given creatine alongside resistance training, vegetarians gained more than meat eaters did, in both muscle content and work performed [8]. There is no blood test worth ordering for it, so this is one to take rather than measure.
Creatine monohydrate is the form with the evidence behind it, and five grams a day is the dose. Ignore anything sold as advanced, buffered or liquid: they cost more and none has beaten plain monohydrate.
It works alongside resistance training rather than instead of it. The trial above paired the two, and that is how the benefit was measured.
A few things here are not a self-ordered panel question.
Two of the things worth doing here are not tests at all: iodized salt in the cupboard, and a B12 tablet you take without asking whether you need it. The rest is a short list, checked once and acted on. If you have your numbers, seeing where each one sits against the range the evidence supports is the next thing worth doing.