The Most Helpful Blood Tests for Vegans

One of the biggest concerns for people following a vegan diet is whether or not they’re deficient in key nutrients, and a common method for determining this is through blood work. But which blood tests for vegans are the most helpful? We’ll discuss these below!

Should vegans get their blood tested?

While vegans and people on a whole food plant based diet can be at higher risk of deficiency for certain nutrients, this doesn’t mean that they automatically need to have their blood tested for every possible nutrient deficiency just because they’re vegan or plant-based.

What’s most important for vegans is to focus on eating enough foods rich in key nutrients and by taking supplements if getting enough from food isn’t feasible.

Blood tests may be recommended by a healthcare professional if you’re experiencing signs or symptoms of nutrient deficiency or toxicity, or as part of a yearly wellness checkup. Of course, some vegans prefer having the peace of mind that comes with a normal blood test result and may wish to have their blood tested for additional nutrients.

Blood tests for vegans

While there are blood tests generally ordered for everyone regardless of diet (such as a complete blood count, or “CBC”), some tests are more relevant to vegans and are recommended more often.

Vitamin B12

It’s often recommended for vegans to have their serum vitamin B12 levels checked since plant-based foods providing reliable amounts of this vitamin are not common. Vegans can get enough vitamin B12 by consuming fortified foods like non-dairy milks, nutritional yeast, and breakfast cereals which have had vitamin B12 added to them or by taking a supplement.

Our bodies store enough vitamin B12 to last for a few years, but after this period of time vegans are at very high risk for developing a vitamin B12 deficiency if they don’t eat fortified foods and don’t supplement. A deficiency in this vitamin can lead to serious health complications including anemia and damage to the brain and nerves.

Low levels of vitamin B12 may mean that you have a vitamin B12 deficiency from not consuming enough foods or supplements with vitamin B12. It could also indicate pernicious anemia, which results from poor absorption of vitamin B12 in the small intestine. A physician will be able to determine whether your vitamin B12 levels are low due to low dietary consumption or poor absorption.

Two additional blood tests related to vitamin B12 deficiency include:

• Methylmalonic acid (MMA) – this test can help your doctor in diagnosing a vitamin B12 deficiency. When the body doesn’t have enough vitamin B12, it will produce excess MMA, so a high MMA test result may indicate a vitamin B12 deficiency.
• Homocysteine – vitamin B12 helps break this amino acid down in the body to be used in various biochemical reactions. When vitamin B12 is lacking, homocysteine levels will rise. Therefore, a high homocysteine test result may indicate a vitamin B12 deficiency or even a subclinical deficiency, which occurs when vitamin B12 levels are low but the person lacks any tell-tale symptoms.

Bottom line: Your doctor may recommend getting a vitamin B12 test if they suspect that you’re deficient. Getting tested soon after going vegan likely isn’t necessary since the body’s stores of B12 can last for a few years. Vegans who eat enough vitamin B12-fortified foods and/or take a supplement should have adequate levels of this vitamin in their blood, except for rare cases where vitamin B12 isn’t absorbed properly. Having your vitamin B12 levels tested is largely a matter of personal preference.

Vitamin D

Vitamin D levels are often a big concern, which makes sense considering how prevalent vitamin D deficiency is. In the United States, it’s estimated that about 24% of people¹ have a vitamin D deficiency. Vitamin D plays a key role in bone health, but is regular vitamin D testing helpful?

The U.S. Preventive Services Task Force² actually doesn’t recommend regular vitamin D testing for people who don’t have signs or symptoms of a deficiency. Experts currently don’t agree on what levels of vitamin D in the body are optimal or what levels indicate a deficiency. The research on vitamin D is also somewhat conflicting, with the reported prevalence of vitamin D deficiency varying drastically between studies. 

However, considering that plant-based foods high in vitamin D are lacking (apart from fortified non-dairy milks and irradiated mushrooms), it’s likely wise for vegans to have their vitamin D levels tested every few years or so. This is especially true for vegans who do not take a supplement, who don’t spend much time in the sun, who have darker skin, or who live in regions without much sunlight. 

Something to keep in mind is that vitamin D levels may not be as directly related to bone health outcomes for some people. For example, Black Americans with low levels of vitamin D in their blood tend to have fewer bone fractures³ and osteopenia and higher bone mineral density than Caucasians with similar vitamin D levels. That being said, it’s still important for Black vegans to get enough vitamin D considering how important it is for reducing the risk of many chronic diseases⁴.

Bottom line: Vegans may wish to get their vitamin D levels tested every few years or so, especially those who live in cold areas, who have darker skin, who don’t consume fortified foods or supplements, and who don’t spend time outdoors without sunscreen.

Iron (serum ferritin)

Contrary to popular belief, vegans are not at higher risk of iron deficiency than the general population despite having lower iron stores. However, it is wise for vegans (especially pre-menopausal women) to have their iron levels checked regularly since iron deficiency is fairly common overall.

The blood test for iron checks your levels of ferritin, a protein that stores iron in the body. Ferritin is a good marker of long-term iron consumption. A low ferritin test result may mean that you have low iron stores.

Two additional blood tests related to iron include:

• Hemoglobin – hemoglobin is a protein in red blood cells. If hemoglobin levels are low, it can mean that you don’t have enough red blood cells in your blood. Since iron is required for red blood cell production, being deficient in iron can lead to low red blood cell production and, in turn, low hemoglobin levels. It can help your physician in diagnosing iron-deficiency anemia.
• Total Iron Binding Capacity (TIBC) – this test measures how much transferrin (a protein) is attached to iron in the blood. Iron can’t move through the bloodstream by itself and needs transferrin for assistance. If your TIBC test result is high, it means that there is a lot of free transferrin not attached to any iron molecules. This can help indicate that your iron levels are low.

Bottom line: It can be helpful for vegans to regularly have their iron levels checked, especially those who are pre-menopausal or who are experiencing fatigue.

Omega-3 fatty acids

While not commonly assessed in bloodwork, omega-3 fatty acids play an important role in cardiovascular health, brain health, and reducing inflammation in the body.

There are three types of omega-3 fatty acids: 

• Alpha-linolenic acid (ALA), found in some plant-based foods like flax seeds, chia seeds, walnuts, canola oil, and hemp seeds
• Docosahexaenoic acid (DHA), found in fatty fish and algae
• Eicosapentaenoic acid (EPA), also found in fatty fish and algae

While all three provide important health benefits, most of the research on omega-3s for cardiovascular health have focused on DHA and EPA, which are much more difficult to get on a vegan diet without an algae-based DHA/EPA supplement. Fortunately, the body can convert ALA from plant-based foods to DHA and EPA. Unfortunately, the rate at which this happens is quite low. Therefore, it’s recommended that vegans get even more ALA than omnivores to make up for the low conversion rate. 

Since the rate for converting ALA to DHA and EPA is low and not well understood, some vegans may wish to test the levels of omega-3s in their blood just to be safe. The Omega-3 Index is currently one of the best options for assessing omega-3 status, since it reflects long-term consumption and isn’t as influenced by recent meals⁵ as serum or plasma levels are. 

The Omega-3 Index is a blood test that measures the number of fatty acids in the membranes of your red blood cells, including DHA and EPA. Results are given as a percentage, specifically what percent of the total fatty acids in your blood cells are DHA and EPA. This percentage will inform you about your risk for heart disease based on the amount of DHA and EPA in your blood.

Bottom line: This test is likely most useful for vegans who don’t take an algae-based DHA/EPA supplement and who prefer to get their omega-3s from food, since it will give you an idea of whether the conversion of ALA to DHA and EPA is adequate. It can be a helpful tool when working with a registered dietitian to determine whether more ALA-rich foods are needed in the diet and whether a vegan DHA/EPA supplement is warranted.

Is albumin a helpful blood test for vegans?

Albumin is included as part of a comprehensive metabolic panel (CMP) test, which is often checked yearly for most people. 

Some vegans may worry that a low serum albumin result means that they are protein deficient. They may even be told that they are protein deficient by their physician and encouraged to start including more animal protein. But are albumin levels really indicative of not getting enough protein? To understand this, let’s learn a little more about albumin.

Albumin is a protein made in the liver and which circulates in the bloodstream, helping to maintain oncotic pressure in the vessels and prevent fluid from leaking out. It also helps transport molecules in the bloodstream, such as some vitamins, enzymes, fatty acids, and medications. 

Albumin is not a very helpful marker for determining a person’s long-term nutrition status or whether they’re getting enough protein in their diet. In fact, the link between serum albumin and nutritional intake⁶ is quite weak.

So if your albumin results come back low, it’s probably not because your diet is too low in protein. Of course, it’s possible that you may have a low albumin result and not have been eating enough protein if you’ve been ill and not eating much, but the albumin result itself can’t tell us much about protein intake. According to the Cleveland Clinic⁷, low albumin is more directly related to:

• Fluid overload (having too much fluid in the body, as can happen with congestive heart failure, liver disease, and kidney disease requiring dialysis)
• Infection
• Physiologic stress resulting from disease
• Hypothyroidism
• Wound healing
• Malnutrition (due to low calories overall, not just low protein)
• Inflammation
• Pregnancy
• Cancer
• Nephrotic syndrome

Summary

While there’s no need for vegans to get every blood test known to man, some tests can be helpful for catching nutrient deficiencies before they begin to cause problems. 

You can have your vitamin B12 levels tested for peace of mind, but your main focus for vitamin B12 should be getting enough from fortified foods and/or a supplement. Having vitamin D, iron, and the Omega-3 Index checked is a good idea for most vegans.

It’s crucial that vegans get enough of these nutrients from food, supplements, or a combination of both for optimal health. If you aren’t sure whether you’re getting enough of these nutrients or if you need help finding ways to increase your intake, a registered dietitian (like myself) can help!

References

1. Amrein K, Scherkl M, Hoffmann M, Neuwersch-Sommeregger S, Köstenberger M, Tmava Berisha A, Martucci G, Pilz S, Malle O. Vitamin D deficiency 2.0: an update on the current status worldwide. Eur J Clin Nutr. 2020 Nov;74(11):1498-1513. doi: 10.1038/s41430-020-0558-y. Epub 2020 Jan 20. PMID: 31959942; PMCID: PMC7091696.
2. LeFevre ML; U.S. Preventive Services Task Force. Screening for vitamin D deficiency in adults: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med. 2015 Jan 20;162(2):133-40. doi: 10.7326/M14-2450. PMID: 25419853.
3. Brown LL, Cohen B, Tabor D, Zappalà G, Maruvada P, Coates PM. The vitamin D paradox in Black Americans: a systems-based approach to investigating clinical practice, research, and public health – expert panel meeting report. BMC Proc. 2018 May 9;12(Suppl 6):6. doi: 10.1186/s12919-018-0102-4. PMID: 30044889; PMCID: PMC5954269.
4. Harris SS. Vitamin D and African Americans. J Nutr. 2006 Apr;136(4):1126-9. doi: 10.1093/jn/136.4.1126. PMID: 16549493.
5. National Institutes of Health Office of Dietary Supplements. Omega-3 Fatty Acids Health Professional Fact Sheet. https://ods.od.nih.gov/factsheets/Omega3FattyAcids-HealthProfessional/. Accessed May 16, 2023.
6. Soeters PB, Wolfe RR, Shenkin A. Hypoalbuminemia: Pathogenesis and Clinical Significance. JPEN J Parenter Enteral Nutr. 2019 Feb;43(2):181-193. doi: 10.1002/jpen.1451. Epub 2018 Oct 4. PMID: 30288759; PMCID: PMC7379941.
7. Cleveland Clinic. Hypoalbuminemia. https://my.clevelandclinic.org/health/diseases/22529-hypoalbuminemia. Accessed May 2015, 2023.