Ensuring Adequate Zinc Status in Vegans
Stewart D Rose and Amanda J Strombom*
Plant-Based Diets in Medicine, USAPlant-Based Diets in Medicine, USA
Submission:November 22, 2019; Published: December 18, 2019
*Corresponding author:Amanda Strombom, Plant-Based Diets in Medicine, 12819 SE 38th St, #427, Bellevue, WA 98006, USA
How to cite this article: Stewart D Rose, Amanda J Strombom. Ensuring Adequate Zinc Status in Vegans and Vegetarians. Adv Res Gastroentero
Hepatol, 2019; 14(3): 555887. DOI:10.19080/ARGH.2019.14.555887.
Zinc is an essential mineral that is naturally present in some foods, added to others, and available as a dietary supplement. It is involved in numerous aspects of cellular metabolism, and also supports normal growth and development. Frequent intake of zinc is required to maintain a steady state because the body has no specialized zinc storage system. Zinc is available from many plant foods. Protein increases zinc absorption. Because of this, foods high in protein and zinc, such as legumes and nuts, are good choices. Zinc deficiency is characterized by growth retardation, loss of appetite, and impaired immune function.
Zinc nutritional status is difficult to measure adequately using laboratory tests. Clinical effects of zinc deficiency can be present in the absence of abnormal laboratory indices. Adverse health effects have not been commonly demonstrated with varied, plant-based diets consumed in developed countries. Supplements are an option for those with potential deficiencies. Both zinc gluconate and zinc citrate are well-absorbed. However, zinc supplements have the potential to interact with several types of medications.
Keywords:Nutritional status; Zinc; Zinc gluconate; Zinc citrate; Medications; Plant foods; Cellular metabolism; Immune function; Protein synthesis; Lactic dehydrogenase; Protein; Growth retardation; Loss of appetite; Impaired immune function
Zinc is an essential mineral that is naturally present in some foods, added to others, and available as a dietary supplement. Zinc is involved in numerous aspects of cellular metabolism. It is required for the catalytic activity of approximately 100 enzymes [1,2] and it plays a role in immune function [3,4], protein synthesis , wound healing , DNA synthesis [2,4], and cell division .
Zinc also supports normal growth and development during pregnancy, childhood, and adolescence [6-9] and is required for proper sense of taste and smell . Importantly, Zinc is an integral part of carbonic anhydrase and lactic dehydrogenase .
A frequent intake of zinc is required to maintain a steady state because the body has no specialized zinc storage system  (Table 1).
(Table 2) Protein increases zinc absorption. Because of this, foods high in protein and zinc, such as legumes and nuts, are good choices . If a food doesn’t have much protein, it can still be accompanied by one that does in order to enhance absorption.
Zinc deficiency is characterized by growth retardation, loss
of appetite, and impaired immune function. In more severe
cases, zinc deficiency causes hair loss, diarrhea, delayed sexual
maturation, impotence, hypogonadism in males, and eye and skin
lesions [2,8,13,14].Weight loss, delayed healing of wounds, taste
abnormalities, and mental lethargy can also occur [8,5,15-19].
Many of these symptoms are non-specific and often associated
with other health conditions; therefore, a medical examination
is necessary to ascertain whether a zinc deficiency is present.
Zinc nutritional status is difficult to measure adequately using
laboratory tests [2,20,21] due to its distribution throughout the
body as a component of various proteins and nucleic acids 
Plasma or serum zinc levels are the most commonly used indices
for evaluating zinc deficiency, but these levels do not necessarily
reflect cellular zinc status due to tight homeostatic control
mechanisms . Clinical effects of zinc deficiency can be present
in the absence of abnormal laboratory indices .
The zinc deficiencies commonly associated with plant-based
diets in impoverished nations are not associated with vegetarian
diets in wealthier countries . Adverse health effects have not
been demonstrated with varied, plant-based diets consumed in
developed countries .
Well-planned vegetarian diets can provide adequate
amounts of zinc from plant sources. Vegetarians appear to adapt
to lower zinc intakes by increased absorption and retention
of zinc. Studies show vegetarians have similar serum zinc
concentrations to, and no greater risk of zinc deficiency than,
non-vegetarians despite differences in zinc intake .
A meta study showed that zinc intake by vegetarians was only
slightly lower than their omnivorous counterparts. It showed
vegans to have only a slightly lower serum zinc level than nonvegetarians,
a difference of 1.17 ± 0.45 μmol/l . Average
serum zinc levels are from 10 to 15 μmol/l . Therefore the
clinical relevance may be minimal. Existing data indicate no
differences in serum zinc or growth between young vegetarian
and omnivorous children .
Pregnant women are vulnerable to a low zinc status due
to the additional zinc demands associated with pregnancy and
fetal development. A meta study found the pregnant vegetarian
women consume on average, about 1.4mg per day less than
their omnivorous pregnant women . Supplements may
be necessary for pregnant women. Although vegans have
lower zinc intake than omnivores, they do not differ from the
nonvegetarians in functional immunocompetence as assessed
by natural killer cell cytotoxic activity . It appears that
there may be facilitators of zinc absorption and compensatory
mechanisms to help vegetarians adapt to a lower intake of zinc
There has long been a theoretical concern about the larger
intake of phytates in plant foods inhibiting mineral absorption
of some minerals, such as zinc, in those following a vegetarian
diet. However, there was little evidence of deficiency commonly
occurring in practice. Part of the answer lies in the microbiota
of the vegetarian. It turns out that their flora act to degrade
phytate, thus allowing for good absorption of minerals. One
recent study concludes that, “it was the vegetarians’ microbiota
that particularly degraded up to 100% phytate to myo-inositol
phosphate products.” A diet rich in phytate increases the
potential of intestinal microbiota to degrade phytate. The cooperation
of both aerobic and anaerobic bacteria is essential for
the complete phytate degradation .
The vegetarian diet compared with a meat-based diets
resulted in lower amounts of absorbed Zn due to a higher
content of Zn in the meat diets, but no difference was observed
in the fractional absorption of zinc despite a high intake of
phytates . The presence of garlic and onion very significantly
increased the bioavailability of zinc from grains .
Both zinc gluconate and zinc citrate are well-absorbed .
Zinc picolinate is also thought to well absorbed . However,
zinc oxide, which is used in many supplements because it’s
cheaper, may not be well absorbed by some people . Note
that in the case of zinc, the Supplement Facts panel on the
supplement container is required to list the elemental zinc
content, as opposed to the compound.
Zinc supplements have the potential to interact with several
types of medications
Antibiotics: Both quinolone antibiotics (such as Cipro®) and
tetracycline antibiotics (such as Achromycin® and Sumycin®) interact with zinc in the gastrointestinal tract, inhibiting the
absorption of both zinc and the antibiotic [36,37]. Taking the
antibiotic at least 2 hours before or 4–6 hours after taking a zinc
supplement minimizes this interaction .
Penicillamine: Zinc can reduce the absorption and action
of penicillamine, a drug used to treat rheumatoid arthritis
. To minimize this interaction, individuals should take zinc
supplements at least 2 hours before or after taking penicillamine
Diuretics: Thiazide diuretics such as chlorthalidone
(Hygroton®) and hydrochlorothiazide (Esidrix® and
HydroDIURIL®) increase urinary zinc excretion by as much as
60% . Prolonged use of thiazide diuretics could deplete zinc
tissue levels, so clinicians should monitor zinc status in patients
taking these medications.
Institute of Medicine (US) Panel on Micronutrients. (2001) Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington DC: National Academies Press (US).