1. On p. 8 of the Executive Summary for their 2010 Dietary Reference Intakes for Calcium and Vitamin D, the Institute of Medicine says that they are basing their recommendations on a vitamin D level of 16 to 20 ng/ml of 25(OH)D. I have been using that as the level to indicate adequate vitamin D. But later in the document (p. 14), they talk about ideal levels some more and conclude that less than 20 ng/dl might be potentially too low for some people and therefore they recommend at least 20 ng/ml.
I have changed the levels in my calcium and vitamin D articles to reflect this. (Thanks, Brandon!)
2. In the table of calcium in plant foods, I had listed the wrong amount of calcium in a 1/2 cup serving of “Mustard greens – frozen, cooked, boiled, drained, chopped” as 107 mg. It is actually 76 mg.
I do not take this lightly. A 7-year-old vegan boy from San Diego was found to have vitamin B12 deficiency severe enough to cause neurological problems (1).
In the months before he was admitted, he would engage in obsessive–compulsive behavior, including lining up his toys, repetitive stair climbing, and difficulty concentrating. Eventually he developed a widened gait (i.e., he couldn’t walk normally) and was taken to the hospital. His vitamin B12 level was 109 pg/ml (normal range is above 250 pg/ml).
Luckily, the child made an almost full neurological recovery after two months of vitamin B12 treatment.
The boy was also somewhat malnourished and had previously had teeth extracted due to “poor dentition.”
So where is the progress?
The progress is in the sensitive write-up performed by the researchers who did not disparage the vegan diet for children or try to convince the parents to feed the child animal products. Rather, they pointed out some benefits of a vegan diet for children, while cautioning that it needs fortification with vitamin B12.
Let’s hope this child makes a 100% recovery in both his neurological development and his teeth.
1. Crawford JR, Say D. Vitamin B12 deficiency presenting as acute ataxia. BMJ Case Rep. 2013 Mar 26;2013. | link
She has been told to get 1,200 mg of calcium per day. But if the calcium from greens in only absorbed at less than 50%, does that mean she needs to get a higher amount of calcium in her diet so that she absorbs a full 1,200 mg?
The answer is that dietary recommendations are made knowing that a nutrient is only partially absorbed from the diet. It depends on the nutrient and recommendations are made for each nutrient based on its typical absorption rate.
In extreme cases, such as the calcium from spinach that is absorbed at only about 5%, you would need to make modifications to rely only on spinach or foods with a similar absorption rate. But the recommendations for calcium assume that only about 1/3 is going to be absorbed from the best sources (not sure the exact number the Institute of Medicine uses).
But this is a reason why I never mention getting one’s calcium from legumes or nuts and seeds – when you combine their relatively low amounts of calcium and their low absorption rates, you cannot rely on them for the bulk of your calcium needs. They will supply some, but not nearly enough.
Focus on the greens with higher amounts of calcium that is moderate to highly absorbable, calcium-set tofu, and fortified foods or supplements.
Based on some comments by a reader and their finding a chart of oxalate content of various greens published by the USDA (thanks, dimqua!), I decided to more rigorously document the calcium absorption from greens. What I came up with is shown in Table 5 of the (newly renamed) article on bones on VeganHealth.org, Calcium and Vitamin D.
Here is a summary of the findings:
• Studies have shown that calcium in fortified soymilk, bok choy, kale, and mustard greens is absorbed well.
• Based on oxalate levels, the calcium in turnip greens should also be absorbed well.
• Based on oxalate levels, the calcium in collards, broccoli, and watercress should be absorbed moderately well.
• Studies have shown that the calcium in spinach and rhubarb is not absorbed well.
• Based on oxalate levels, the calcium in beet greens should not be absorbed well.
For those of you with infants or thinking about infants, it could be a good resource not only for your own information, but to share with family, friends, doctors, and alternative medicine practitioners.
I just read a very helpful article on kidney stones that I thought I’d pass on. (Thanks, Jeff!) It was written in 2002 but to my knowledge it is still valid. It also had some information on calcium supplements and kidney stones suggesting that calcium supplements taken with meals could reduce the risk of kidney stone formation whereas taken without meals could increase the risk (in genetically predisposed people).
I modified my calcium recommendations to reflect this, and also added a page on kidney stones to VeganHealth.org and am reproducing here:
The article, Diet and Kidney Stones, by James J. Kenney, PhD, RD, FACN is an excellent resource for treating kidney stones with diet.
A quick summary is that people with calcium-oxalate stones, the most common type, should avoid high-oxalate foods (listed in the chart in the article), limit sodium to less than 1,500 mg per day, do not take vitamin C supplements, limit animal protein, and only take calcium supplements with meals.
Drinking as much as 2 to 3 quarts (1.9 to 2.8 liters) a day may help flush out your urinary system. Unless your doctor tells you otherwise, drink enough fluid – mostly water – to produce clear or nearly clear urine.
I received an interesting question from a vegan who is concerned that her manganese intake on a vegan diet is 4 times the DRI of 1.8 mg for women. I thought this was going to be an easy question to answer – probably in 10 minutes or less. Seven solid hours later, I have added a new page to VeganHealth.org, Manganese. It is reproduced here:
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.
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 (6). People with manganese toxicity have more of a tendency to fall backwards than do those with Parkinson’s (6). Studies have been mixed on whether chelation therapy, the only therapy currently available, is successful at treating overt manganese toxicity (6).
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) (1), 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 (6). 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 (3, 4). 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 (2).
People with liver damage are also at risk for manganese deficiency (6).
Manganese absorption is very low, from 1 to 5% (4). The phytic acid in a soy formula was shown to cut manganese absorption in half (from 1.6 to .7%) in adults (5). 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 (5).
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.
1. 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. | link
2. 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) | link
3. 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. | link
4. 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. | link
5. 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. | link
6. 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. | link