by Jack Norris, RD
Depending on the laboratory, a normal range for white blood cell count (WBC) is about 3.5 to 12.5 billion per liter. One cross-sectional study showed vegans have a lower WBC than omnivores, though in the normal range at 5.8 (2). It appears that many vegans, however, have a lower than normal WBC. We don’t really know why this is, but it appears to be rather common and not indicative of any obvious problem.
If you have a WBC below normal, you should talk to your doctor about whether to be concerned.
White Blood Cells in Vegans
White blood cells are needed to fight foreign invaders, including bacteria, viruses, and cancerous cells. During infections, they typically increase in number. A concise explanation of the various white blood cells, along with some interesting pictures, can be found on Wikipedia (link). One type of white blood cells, eosinophils, can increase during allergic reactions (link), though from what I could find, not enough to significantly effect the total white blood cell count.
An apparently healthy, active, vegan, middle-aged woman contacted me saying that she has a low WBC of 2.8 billion per liter. Normal is about 3.5 to 10.5 (1), although this can vary depending on the laboratory.
Knowing that I also usually have a low white blood cell count (that my doctors have never been very worried about), I got out my old lab reports and here is the history (reference range in parentheses):
1999 – 6.3 (4.0-10.5)
2001 – 2.9 (3.5-12.5)
2002 – 3.2 (3.5-12.5)
2005 – 5.0 (3.5-12.5)
2007 – 3.3 (3.5-12.5)
2008 – 3.3 (4.0-10.5)
2013 – 3.6 (4.3-11.0)
I went vegan in 1988, so the initial, higher number in 1999 was not because I had recently been eating animal products.
The reader who wrote me included a March 2006 article from the Vegetarian Society of Hawaii’s Quarterly Newsletter by William Harris, MD, “Low” WBC counts in vegans (PDF). In the article, Dr. Harris explains that his white blood cell count has been as low as 3.0. He says that Agatha Thrash, MD and Michael Klaper, MD told him that they see many vegans with low white blood cell counts. And if you poke around online, you will find that many vegans have low white blood cells.
Dr. Harris also points out a small amount of research on the topic and I’m afraid there hasn’t been much since then.
The main paper we have to go on is Hadded et al., 1999 (2) who found vegans to have an average of 5.0 compared to omnivores who had a count of 5.8 (the difference was statistically significant). As you can see, the vegans’ average white blood cell count of 5.0 falls into the normal range. After considering other immune-related parameters, the authors concluded, “It is not possible to determine from these findings whether the immune status of vegans is compromised or enhanced compared with other groups.”
Dr. Harris goes on to say that “A previous study, Malter M, et al. (3) concluded that ‘Cytotoxic activity…was significantly higher in vegetarians than in their omnivorous controls by a factor of 2. The enhanced natural cytotoxicity may be one of the factors contributing to the lower cancer risk shown by vegetarians.'” That’s good news, but it may not be relevant to those of us with low white blood cells because the abstract points out that in that study, the white blood cells didn’t differ between the vegetarians and non-vegetarians.
A 2007 abstract of an article in Polish found low white blood cells in a group of vegetarians (4), and a 2002 paper in Medical Hypotheses by Mark F. McCarty (5) says there are several reports that link vegan diets to substantial reductions in white blood cells. He cites Haddad et al. (2) and also a number of other papers, but the only one I could get a copy of was of a clinical trial using a vegetarian diet at a health spa in Norway to treat rheumatoid arthritis (6):
At the beginning of the Norway study, the vegetarian group already had a lower white blood cell count than the control group (about 7.0 vs. 7.5). They fasted on vegetable juice for a week and then ate a gluten-free, vegan diet for 3.5 months after the fast. During the vegan diet, foods higher in protein (seeds and lentils) were added at a rate of one new item every couple days. They then ate a vegetarian diet and were allowed to include dairy products and gluten if they chose. After one month, their white blood cells went down to about 5.5 after which they gradually went back up to 6, where they stayed for the remainder of the year. In this case, a relatively low-protein, vegan diet did not cause white blood cells to drop below the normal range.
The other trials cited by McCarty are listed in footnote (7).
There is a 2010 clinical trial from the University of Memphis where mostly healthy and some vegetarian subjects went on a “Daniel Fast” for 21 days, eating no processed or packaged food and only plants, and their WBC went from an average of 5.7 to 5.0 (9).
So why do vegans have lower white blood cell counts than omnivores?
One hypothesis is that we have less of a bacteria, viral, or other toxin load from not eating animal products and, therefore, show lower white blood cells (which typically increase during infections). That seems possible.
The authors of the Daniel Fast study say, “It has been suggested that ingestion of food additives and preservatives can increase white blood cell count by triggering an immune response due to a sensing of invading pathogens from the food stuff; however, we are unaware of any scientific reports that confirm this hypothesis.” But perhaps vegans generally eat less food additives and preservatives and this could be contributing to low WBC.
Another theory is one put forth by MaCarty who says that IGF-1 plays an important role in the production of white blood cells and that since vegans have lower levels of IGF-1, we have lower levels of white blood cells (5).
A third possibility is that low levels of vitamin A could be contributing to low WBC count in vegans. The Linus Pauling Institute says, “Vitamin A and retinoic acid (RA) play a central role in the development and differentiation of white blood cells, such as lymphocytes, which play critical roles in the immune response (8).” Unlike omnivores, vegans do not have a direct, dietary source of vitamin A, but rather get it indirectly via carotenoids (mainly beta-carotene). Beta-carotene is also fat-soluble. It seems theoretically, possible then, that a low intake of carotenoids or fat could contribute to lower vitamin A status and WBC. This is purely hypothetical; to my knowledge vitamin A levels have not been measured in vegans and other signs of low vitamin A status have not been a noted problem. (Anecdotally, I had been eating plenty of beta-carotene and fat at the last measurement of my WBC.)
There are two things to be concerned about with low white blood cells. The first is infections. If you are a vegan with a low WBC, you know whether you are getting infections easily. Anecdotally, I’ve only had one cold in going on 2.5 years, and it was mild. I attribute this to my daily zinc supplementation, but even before I supplemented with zinc, I only got about one cold per year.
The second concern for those of us with white blood cells lower than normal is the possibility of getting cancer. If our white blood cells are low due to lower IGF-1, then our risk of cancer is also possibly lower due to IGF-1 (although the research between IGF-1 and cancer is inconclusive the last I checked). It may be of some solace to know that the only study reporting cancer rates of vegans (for practical purposes), found vegans to have a lower risk (see Take Three: Direct Evidence that Vegans have Lower Cancer Rates).
In summary, we don’t really know why some vegans have lower-than-normal white blood cells, though it does appear to be rather common and not indicative of any obvious problem. If you have a white blood cell count below normal, you should talk to your doctor about whether to be concerned.
Last updated May 2013
2. Haddad EH, Berk LS, Kettering JD, Hubbard RW, Peters WR. Dietary intake and biochemical, hematologic, and immune status of vegans compared with nonvegetarians. Am J Clin Nutr. 1999 Sep;70(3 Suppl):586S-593S.
Schmidt T, Wijga A, Von Zur Mühlen A, Brabant G, Wagner TO. Changes in cardiovascular risk factors and hormones during a comprehensive residential three month kriya yoga training and vegetarian nutrition. Acta Physiol Scand Suppl. 1997;640:158-62. Could not find online.
McCarty also listed the study below (which is the same trial described in Kjeldsen-Kragh et al.’s 1999 paper) saying “see comments”, but I looked up the comments and found nothing about white blood cells.
Kjeldsen-Kragh J, Haugen M, Borchgrevink CF, Laerum E, Eek M, Mowinkel P, Hovi K, Førre O. Controlled trial of fasting and one-year vegetarian diet in rheumatoid arthritis. Lancet. 1991 Oct 12;338(8772):899-902.
9. Bloomer RJ, Kabir MM, Canale RE, Trepanowski JF, Marshall KE, Farney TM, Hammond KG. Effect of a 21 day Daniel Fast on metabolic and cardiovascular disease risk factors in men and women. Lipids Health Dis. 2010 Sep 3;9:94.