Vegan For Life
by Jack Norris, RD &
Ginny Messina, MPH, RD
by Jack Norris, RD | Last updated: June 2013
|Table 1. Zinc Dietary Reference Intake (mg)4|
|0 - 6 mos||2||2|
|7 - 12 mos||3||3|
|1 - 3 yrs||3||3|
|4 - 8 yrs||5||5|
|9 - 13 yrs||8||8|
|14 - 18 yrs||11||9||13||14|
Zinc is not found in large amounts in plant foods, but as far as can be detected, vegetarians have similar zinc status to non-vegetarians (6). The best, common plant sources of zinc are legumes, nuts, seeds, and oatmeal. Table 2 shows the zinc content of selected plant foods.
Symptoms of zinc deficiency include poor growth and delayed sexual maturation in children, poor wound healing, hair loss, impaired immune function, and dermatitis (especially around body orifices) (1).
Phytates, which are commonly found in plant foods, can reduce zinc absorption, and some researchers have suggested that this increases the zinc needs of vegetarians by up to 50% (5).
Despite the lower absorption from plant foods, a 2013 meta-analysis showed vegans to have only a slightly lower serum zinc level than non-vegetarians, a difference of 1.17 ± 0.45 µmol/l (6). For vegetarians in developed countries, the difference was even smaller at .76 ± .27 µmol/l. Absolute values for serum zinc were not given in the analysis. Average serum zinc levels are around 20 µmol/l with a range of about 9 to 30 µmol/l (7), so it's doubtful that the differences are meaningful. One caveat is that serum zinc levels are not necessarily indicative of the zinc levels in cells (8).
Protein increases zinc absorption. Because of this, foods high in protein and zinc, such as legumes and nuts, are good choices (2). The leavening of bread (most bread is leavened) and fermenting of soyfoods (tempeh and miso) also enhances zinc absorption (2).
A modest zinc supplement of 50 to 100% of the RDA should be safe for those who are concerned or having symptoms of zinc deficiency.
|Table 2. Zinc in Plant Foods3|
|Tofu||firm, raw||1/2 cup||2.0|
|Garbanzo beans||boiled||1/2 cup||1.3|
|Pinto beans||boiled||1/2 cup||0.8|
|Kidney beans||boiled||1/2 cup||1.0|
|Peanut butter||2 tbsp||0.9|
|Sunflower seeds||roasted||1/4 cup||1.7|
|Corn||yellow, boiled||1 cup||0.9|
|Cashews||dry roasted||1/4 cup||1.9|
|Chia seeds||dried||1 oz||1.0|
|Broccoli||boiled, chopped||1/2 cup||0.4|
3. USDA National Nutrient Database for Standard Reference. (Link)
4. Dietary Supplement Fact Sheet: Zinc. Office of Dietary Supplements. National Institutes of Health. Accessed 12/15/2010. (Link)
5. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc (2001) Food and Nutrition Board, Institute of Medicine. Accessed 12/28/2010. (Link)
6. Foster M, Chu A, Petocz P, Samman S. Effect of vegetarian diets on zinc status: a systematic review and meta-analysis of studies in humans. J Sci Food Agric. 2013 Apr 17. | link
7. Ghasemi A, Zahediasl S, Hosseini-Esfahani F, Azizi F. Reference values for serum zinc concentration and prevalence of zinc deficiency in adult Iranian subjects. Biol Trace Elem Res. 2012 Dec;149(3):307-14. (Abstract only) | link
8. Dietary Supplement Fact Sheet: Zinc. Office of Dietary Supplements. National Institutes of Health. Last reviewed: June 05, 2013 | link