(Note that I use the term “analogue” to refer to both active and inactive vitamin B12 analogues.)

There is a rumor going ’round that mushrooms are a good source of vitamin B12.

In June, a paper was published looking at the B12 analogue content of mushrooms in Australia (1). The authors used chromatography and mass spectrometry to determine whether the B12 was an active form, and they believed that it was.

The table at this link shows the B12 analogue content of the batches of each mushroom containing the most B12 and the batches containing the least. Assuming that the B12 is active analogue (an assumption that has not been confirmed by testing to see if it lowers MMA levels), it would take anywhere from 7 to 326 cups of mushrooms to meet the RDA.

As for the source of the B12, the authors were not sure, but they said:

“The high concentration of vitamin B12 in peel suggests that it was not synthesized within the mushrooms but was either absorbed directly from the compost or synthesized by bacteria on the mushroom surface. The latter is more likely because mushrooms have no root system to take up the vitamin in the compost as is the case with the uptake of vitamins by root plants from the soil containing fertilizers.”

The take home message: As with anything that has fecal contamination, these mushrooms might be a source of tiny amounts of vitamin B12. For many reasons, vegans should not rely on mushrooms for their B12.

1. Koyyalamudi SR, Jeong SC, Cho KY, Pang G. Vitamin B12 is the active corrinoid produced in cultivated white button mushrooms (Agaricus bisporus). J Agric Food Chem. 2009 Jul 22;57(14):6327-33. PubMed PMID: 19552428.

I always find it amusing when I’m reading nutrition propaganda from someone using outdated information and they say something like, “As far back as [date], we knew that…” And so it disappoints me to have to do the same thing right now: As far back as June, we knew that vegetarians had a lower cancer rate than regular meat-eaters; it’s just that it’s taken me until now to update VeganHealth.org and post about it.

And, why am I saying “regular meat-eaters” rather than just “meat-eaters”? Because, in this report from EPIC-Oxford (1), the people who ate no meat other than fish had an even lower cancer rate than the vegetarians, in comparison to the regular meat-eaters. Here are the rates as compared to regular meat-eaters:

Vegetarians .88 (.81, .96)
Fish-eaters .82 (.73, .93)

Now before anyone says that fish-eaters, therefore, had a lower cancer rate than the vegetarians, let me point out that a cursory glance at those confidence intervals indicates to me that there would not be a statistically significant difference if you compared the vegetarians to the fish-eaters; but the study did not report testing for that.

When breaking the cancers down into categories, in comparison to the regular meat-eaters, the vegetarians had lower rates of stomach (.36, .16-.78), bladder (.47, .25-.89), and lympthatic & hematopoietic tissue (.55, .39-.78) cancer. They had a higher rate of cervical cancer (2.08, 1.05-4.12).

In comparison to the regular meat-eaters, the fish-eaters had lower rates of colorectal (.77, .53-1.13), prostate (.57, .33-.99), and ovarian (.37, .18-.77) cancer. They didn’t have a higher rate of any cancer.

So, can we now say that vegetarians have a lower rate of cancer than meat-eaters? Well, fish-eaters are meat-eaters, so that might be kind of hard. We could say that vegetarians have a lower rate of cancer than chicken eaters.

To see more of the numbers and details, as well as results from other studies on vegetarians and cancer rates, click here.

Footnote

1. Key TJ, Appleby PN, Spencer EA, Travis RC, Allen NE, Thorogood M, Mann JI. Cancer incidence in British vegetarians. Br J Cancer. 2009 Jul 7;101(1):192-7. Epub 2009 Jun 16.

In July, the American Dietetic Association released a new position paper on vegetarian diets. You can click here to read it.

The information is not new, but it’s a good synopsis of all the pertinent research on vegetarian diets. It’s also a handy link to give to all the people out there who still do not think people can be healthy as vegetarians.

I just updated VeganHealth.org with information from an April 2009 review on soy infant formulas (link). Here is an excerpt from the paper:

“Even though soy isoflavones can bind and activate [estrogen receptors (ER)], they do not behave like typical estrogen agonists but rather as selective ER modulators and, in addition, have many other actions that are ER independent, eg, tyrosine kinase inhibition. It is unfortunate that soy isoflavones have been called “phytoestrogens,” because they are not estrogens and are not truly estrogenic at nutritionally relevant concentrations. The weak isoflavone potency for activating the ERs combined with competition with endogenous estrogens for the ERs make isoflavone-related ER activity minimal when fed in amounts similar to those found in [soy formula], even when fed during early development. Moreover, although some studies have shown similar gene expression profiles for genistein (the major soy isoflavone) and [estrogen] in some tissues in vitro and in vivo, ingestion of soy foods results in a complex mixture containing hundreds of phytochemicals and peptides being introduced to the gastrointestinal tract, many of which are absorbed and have biological actions. This situation is not unlike the mixture of phytochemicals found in a typical meal containing a mixed salad and vegetables.”

I just updated Another Internet Soy Article on VeganHealth.org with information on breast cancer. Link. It’s too much to reprint here but it is all good news, with decent evidence that eating soy in moderate amounts can actually decrease the risk of breast cancer. I wouldn’t go so far as to claim that we know it does, but at the very least we can conclude that it doesn’t increase the risk for breast cancer.

Ginny Messina has a blog post on a just-released study putting people on a vegan, Atkins-like diet.

The study is The Effect of a Plant-Based Low-Carbohydrate (“Eco-Atkins”) Diet on Body Weight and Blood Lipid Concentrations in Hyperlipidemic Subjects.

I just added the following to the VeganHealth.org article on disease markers of vegans, and thought it might be of some interest to readers:

Recent research has shown that a BMI of 22.5 to 25.0 is associated with the lowest mortality rate. It has been known for some time that a lower BMI has been associated with an increased risk of death, but that was thought to be due mostly to smoking-related diseases. A 2009 meta-analysis of 900,000 people found that even in those who never smoked, there is a slight increase in mortality below a BMI of 22.5. (1)

The excess mortality below 22.5 has not been explained. One theory is that the excess mortality might be due to lower fat-free mass, which would most likely be lower muscle mass (though could also technically be bones, or even some organs). (1, 2) Studies on BMI and mortality to date have not differentiated between fat and fat-free body mass.

1. Prospective Studies Collaboration, Whitlock G, Lewington S, Sherliker P, Clarke R, Emberson J, Halsey J, Qizilbash N, Collins R, Peto R. Body-mass index and cause-specific mortality in 900 000 adults: collaborative analyses of 57 prospective studies. Lancet. 2009 Mar 28;373(9669):1083-96.

2. Wändell PE, Carlsson AC, Theobald H. The association between BMI value and long-term mortality. Int J Obes (Lond). 2009 May;33(5):577-82.

Alpha-linolenic acid (ALA) is the main omega-3 fatty acid found in plant foods, and it is found in large amounts in flax seeds. A number of studies have found a link between ALA and prostate cancer, but others have not. Until recently, the best review of the literature claimed that ALA does not cause prostate cancer. I thought its logic was sound, but it came from the Flax Council of Canada.

Now a new meta-analysis says that ALA does not cause prostate cancer. The abstract states:

When examined by study type (ie, retrospective compared with prospective or dietary ALA compared with tissue concentration) or by decade of publication, only the 6 studies examining blood or tissue ALA concentrations revealed a statistically significant association. With the exception of these studies, there was significant heterogeneity and evidence of publication bias. After adjustment for publication bias, there was no association between ALA and prostate cancer (RR: 0.96; 95% CI: 0.79, 1.17).

I’ve updated the VeganHealth.org article Omega-3 Fatty Acid Recommendations for Vegetarians with this information.

Nothing major, but I just updated the vitamin D page of VeganHealth.org with results from a study on vitamin D supplementation in older people. It’s short, so I will just cut and paste it here.

Older People

As mentioned in the recommendations, elderly people need 30 minutes a day of direct sunlight in order to produce adequate vitamin D.

A 2009 study from Ireland showed that people aged 64 years or older needed 15 mcg (600 IU) per day to bring vitamin D levels from an average of 55 nmol/L to 74 nmol/L. The researchers estimated that it would take about 40 mcg (1600 IU) per day to raise 97.5% of the participants’ vitamin D levels to 80 nmol/L.

Although some researchers recommend maintaining vitamin D levels at 80 nmol/L, there is not enough evidence to know that there is much of a difference between 74 and 80 nmol/L. For this reason, the recommendation of 25 mcg (1,000 IU) should suffice for people aged 64 and older.

In April, a cross-sectional study was published looking at the bone mineral density (BMD) of vegan, Buddhist nuns in Vietnam:

Ho-Pham LT, Nguyen PL, Le TT, Doan TA, Tran NT, Le TA, Nguyen TV. Veganism, bone mineral density, and body composition: a study in Buddhist nuns. Osteoporos Int. 2009 Apr 7. [Epub ahead of print]

The nuns were lifelong and mostly vegan (some ate some dairy). They were matched with meat-eaters from the community. Participants were 50 to 85 years old. The nuns had the same BMD as the meat-eaters, while only eating about half the calcium: 330 mg per day vs. 682 mg for the meat-eaters. The researchers reported that the osteoporosis rates in these groups were about the same as in the greater population (approximately 20%).

Cross-sectional studies are very limited in their ability to determine cause-and-effect. We do not know if there were nuns who stopped being vegan after getting osteoporosis. It seems that the researchers could have made an effort to investigate this possibility, but they didn’t report that they did.

While this was good news for these nuns, it concerns me that the take home message is that vegans only need 300 mg/day of calcium.

A more relevant study – the most important to date on vegan bone health – is a 2007 analysis from EPIC-Oxford which found that vegans had higher rates of fracture than those in other diet groups. When they adjusted for calcium intake, they found that vegans who ate 525 mg of calcium per day had the same fracture rates as the other diet groups. This was a prospective study which means they followed vegans (and other diet groups) through time, which is a better way to find associations than are cross-sectional studies. It is the only prospective study ever done on vegan bone health.

To date, the best evidence shows that vegans should get at least 525 mg of calcium per day. I recommend at least 700 mg for adults and 1,000 mg for teens.

For more detailed information on vegans, calcium, and vitamin D click here.