by Jack Norris, RD
There is a concern that manganese intakes in vegan diets can be high. To date, manganese toxicity in vegans has not been studied, but manganese toxicity usually does not occur with amounts of manganese found in the diet. However, iron deficiency can cause an increase in manganese absorption and vegans with iron deficiency should make sure they eat vitamin C at meals so that iron is absorbed instead of manganese.
Manganese in Vegan Diets
Manganese is a mineral that is essential for humans. It is part of the antioxidant system in the mitochondria, and is also involved in metabolism, bone development, and the creation of collagen for wound healing. Manganese is found in a wide range of plant foods.
Although manganese is an essential nutrient, manganese toxicity has been relatively common in places where workers are accidentally exposed to large amounts of manganese. Manganese in drinking water is the biggest concern since manganese in food is not as easily absorbed.
Manganese toxicity symptoms tend to be neurological problems. Headaches, muscle cramps, fatigue, and aggressiveness are early signs of manganese toxicity, which can then proceed into Parkinson’s disease-like symptoms such as tremors (Aschner, 2009). People with manganese toxicity have more of a tendency to fall backwards than do those with Parkinson’s (Aschner, 2009). Studies have been mixed on whether chelation therapy, the only therapy currently available, is successful at treating overt manganese toxicity (Aschner, 2009).
According to the Linus Pauling Institute, “A single case of manganese toxicity was reported in a person who took large amounts of mineral supplements for years, while another case was reported as a result of a person taking a Chinese herbal supplement. Manganese toxicity resulting from foods alone has not been reported in humans, even though certain vegetarian diets could provide up to 20 mg/day of manganese.”
The DRI for manganese if 1.8 mg for adult women and 2.3 mg for men. One study has measured the manganese intakes in vegans and it found an average intake of 4.1 mg for women and 5.6 mg for men (not including supplements) (Haddad, 1999), though some vegans get much higher amounts. The upper tolerable limit for adults is 11 mg/day, although this level is considered “very conservative” by the Linus Pauling Institute.
Despite the fact that overt manganese toxicity from food rarely occurs, iron deficiency has been shown to increase the risk of manganese accumulation in the brain (Aschner, 2009). Because iron and manganese share similar absorption mechanisms, iron deficiency can increase manganese intake (from the body trying to increase iron absorption but getting manganese instead) and high manganese intakes can depress iron absorption (Kim, 2010; Finley, 1999). A study in miners whose drinking water was contaminated with manganese showed that manganese toxicity decreased iron status which returned to normal after the manganese was minimized in their environment (Boojar, 2002).
People with liver damage are also at risk for manganese deficiency (Aschner, 2009).
Manganese absorption is very low, from 1 to 5% (Finley, 1999). The phytic acid in a soy formula was shown to cut manganese absorption in half (from 1.6 to .7%) in adults (Davidsson, 1995). Phytic acid has a similar effect on iron absorption, but vitamin C can overcome phytic acid’s effect on iron, whereas it does not do so for manganese (Davidsson, 1995).
From this research, it seems possible that long-term iron deficiency (not necessarily anemia, but low iron stores) could increase manganese absorption on a vegan diet high enough to cause problems, though I have not heard of any long term vegans getting Parkinson’s-like symptoms or manganese toxicity.
Vegans with iron deficiency should make sure they eat vitamin C at meals so that iron is absorbed instead of manganese. Including some soy with meals for phytic acid might also be a good idea for such people.
Last updated: March 2013
Aschner, 2009. Aschner M, Erikson KM, Herrero Hernández E, Tjalkens R. Manganese and its role in Parkinson’s disease: from transport to neuropathology. Neuromolecular Med. 2009;11(4):252-66. doi: 10.1007/s12017-009-8083-0. Epub . Review. Erratum in: Neuromolecular Med. 2009;11(4):267.
Boojar, 2002. Boojar MM, Goodarzi F, Basedaghat MA. Long-term follow-up of workplace and well water manganese effects on iron status indexes in manganese miners. Arch Environ Health. 2002 Nov-Dec;57(6):519-28. (Abstract)
Davidsson, 1995. Davidsson L, Almgren A, Juillerat MA, Hurrell RF. Manganese absorption in humans: the effect of phytic acid and ascorbic acid in soy formula. Am J Clin Nutr. 1995 Nov;62(5):984-7.
Finley, 1999. Finley JW. Manganese absorption and retention by young women is associated with serum ferritin concentration. Am J Clin Nutr. 1999 Jul;70(1):37-43.
Haddad, 1999. 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.
Kim, 2010. Kim Y, Lee BK. Iron deficiency increases blood manganese level in the Korean general population according to KNHANES 2008. Neurotoxicology. 2011 Mar;32(2):247-54. doi: 10.1016/j.neuro.2010.12.006. Epub 2010 Dec 21.
10 thoughts on “Manganese”
I wish someone would market an ultra-low-dose vitatmin C that would be convenient to take with meals. I know it’s not that hard to eat something fresh with each meal, but in reality that doesn’t always happen, and a little extra C as backup wouldn’t hurt, I don’t think?
What about a small glass of orange juice?
I know this is a very old post, but I’m hoping for some advice.
While juggling certain foods within Cronometer, with the intention of hitting daily goals, I keep coming up against (and blowing through that 11g upper-limit). Seems that oats, potatoes and rice, chick-peas and tvp are causing issues. It’s not like they are in huge quantities, either.
Is there any cause for me to be worried when going over, and is there a safe figure I can change the limit to?
The entire article is an attempt to answer the question you’ve posed. This is probably the most relevant excerpt:
Manganese toxicity resulting from foods alone has not been reported in humans, even though certain vegetarian diets could provide up to 20 mg/day of manganese.
Thanks for taking the tine to reply. And yes, I did realise it was all covered. But I got to the end of the post and still didn’t feel very confident. It wasn’t so much in what you said, but in that Red Cronometer bar being set so low, and at ‘difficult’ levels for vegans (Surprises me that the average vegan would be getting so low, given common reliance on grains).
Do you think it’s ok to change the upper-limit, then? Also, would be curious to know what you and the vegans in your circle average at…if you feel happy to share.
I also just found this vide:
Pretty much agrees with you on major point, but still cautions keeping within the guidelines, as often as possible. Haha! What fun 😉
I’m not aware of any reliable measurements of the average intake of manganese for vegans, nor have I ever tried to measure my own. While it’s theoretically possible that high manganese intakes are having a negative impact on the health of some vegans, we don’t have any evidence of it. If you see that there are particular foods pushing your manganese intakes especially high, and you can conveniently replace such foods with others, then it might be worth doing, though I’m not convinced that it is. In other words, I wouldn’t worry about it.
“In other words, I wouldn’t worry about it.”
Thanks! I’m happy to go with that advice. I don’t often track with Cronometer anymore, but it was just something that stuck out. Have changed the upper-limit and will leave it there.
Thanks, again. All the best for ’22
Can I ask why copper is not mentioned on this website? Copper Toxicity is a major issue amongst many vegans and vegetarians. You have a great website with lots of info, could you please share the facts on copper and how to avoid copper toxicity as a vegan? (I’m a nutritionist and I always suggest 30mg zinc supplement daily with food in the form of chelate or picolinate), but also increasing molybdenum, vitamin C, and chromium.
Can you explain what evidence you have that copper toxicity is a major issue for vegans and vegetarians? Theoretically, I understand that vegans can have high copper intakes and that their low zinc intakes could contribute to higher copper absorption, but I’m not aware of any verified cases of copper toxicity in vegans.