The further a society drifts from the truth, the more it will hate those who speak it. ... In a time of deceit, telling the truth is a revolutionary act. George Orwell

Tuesday, October 19, 2010

Alzheimer's, B12 and homocysteine - vegans beware!


This is based on the newly published Scandinavian study:
Homocysteine and holotranscobalamin and the risk of Alzheimer disease


Results: The odds ratios (ORs) (95% confidence interval [CI]) for AD were 1.16 (1.04–1.31) per increase of 1 µmol/L of tHcy at baseline and 0.980 (0.965–0.995) for each increase of 1 pmol/L baseline holoTC.

Notice how did the authors skillfully manage to conceal the impact (really huge!) - by not putting the risk ratio over the full range in the abstract. Instead they mitigated their grant-loosing risk by showing only an incremental change per 1umol/L or per 1pmol/L of the intependent varaibles. (Note: tHcy=homocysteine, holoTC=B12, AD=Alzheimer's Disease).

The impact seems to be huge indeed, based on some quick-and-dirty calculations of the typical tHcy and B12 variability among some populations. Taking two other studies (see [1] and [2] below) giving the average difference between vegetarians and non-vegetarians for tHcy and B12 ( 2.6 to 12.3 umol/L and -94 to -195 pmol/L respectively),   applying the above incremental ratios of (1.16 and 0.980 respectively) one obtains the estimated ralative risk ratio for AD for vegetarians versus non-vegetarians of: 1.5 to 6.2 based on the homocysteine, and 6.7 to 51 based on the B12 data.

(Disclaimer: risk ratio estimates that are based on statistical data do not prove nor disprove causuation.)

My conclusion: the study indicates that the B12 defficiency as well as (independently) high homocysteine seem to be very strong predictors of Alzheimer's disease risk. The overal risk estimate is also much stronger than the washed-out figures presented in the paper's abstract. This should be of utmost importance for vegans and vegetarians!

See also:

1. Effect of Vegetarian Diet on Homocysteine Levels

2. Plasma Homocysteine Levels in Taiwanese Vegetarians Are Higher than Those of Omnivores

3. BBC Health News: Vitamin B12 link to Alzheimer's backed by study

4. BBC Health News: Vitamin B 'puts off Alzheimer's'



Mike said...

"Instead they mitigated their grant-loosing risk by showing only an incremental change per 1umol/L or per 1pmol/L of the independent variables."

Ha! I actually laughed out loud at this comment. Great post and excellent observation, Stan!

pontia said...

but vegan diet is able to lower homocysteine level by itself, without B vitamin supplementing:

Alzheimer - is meateater's desease, then - BEWARE:))

Stan (Heretic) said...

Hi pontia,

I doubt it! The study you quoted was only 1 week long, while other studies (see ref 1 and 2 plus many other generally show that vegetarians and vegans have higher levels of homocycteine and I came of one report of higher rate of degenerative brain disease.

Another factor is a direct neuroprotective effect of ketone bodies (see for example this). Ketone bodies require effective fatty metabolism and their production is suppressed during high carbohydrate meals and some time thereafter. Best way of maintaing high ketone bodies is NOT to consume a high carb diet including most vegetarian diet.

There is also a series of reports such as this linking Alzheimer's with diebetes, as being a form of insulin resistance.

Insulin resistance becomes less relevant when ketone bodies are provided as a fuel to the neural cells just as glucose becomes less relevant to diabetic if he consumes more fat and simultaneously much less glucose.

Once body metabolism switches to using mostly fat (fat means also ketone bodies) for energy then the malfunction of insulin production (dm type 1) or insulin effectiveness (dm type 2 or hypothetically Alzheimers = type 3) become less relevant and allow a patient to improve. I think, the similar benefit of fat/ketone bodies (contra-indicating a high carb diet) one observes in case of epileptic patients.


slanted said...

This discussion makes no sense whatsoever. Alzheimer's rates have gone through the roof in the past 70 years - and guess what, so has meat & sugar consumption. People are eating less of a vegetarian diet, not more. That being said, vegans still need to watch their B-12, but a deficiency in that vitamin is certainly not the primary cause of Alzheimer's.

Stan (Heretic) said...

Hi slanted,

Those risk estimates are statistical correlations, not a proof of the cause and effect. Still it's worth considering a possibility that there may be a causual connection. There is a possibility, for example, that adding even a small amount of fish or eggs to a vegetarian diet may turn out to completely alleviate the risk!

There indeed may be more factors (such as DHA and EPA defficiency) contributing to vegetarians having higher risk for neuro-degenerative diseases. More on this subject: ALS article or Dr.Fuhrman's warning about Parkinson's.

Anonymous said...

Stan, sorry but you just look like "stupid false intelligent people".

Here is some link that explain the exact inverse that you re saying:
Indian village may hold key to beating dementia

Etc etc…

definitely, go for vegan if you want to keep the small brain you still have ;)

Stan (Heretic) said...

The Times Of India article you quoted says: "Too much of an amino acid typically found in red meats, fish, beans, eggs, garlic, lentils, onions, yogurt and seeds can increase the risk of Alzheimer's disease, says a new study."

So, no beans, lentils, onions and no seeds either! To bad it is all garbage.


Thank you for posting the links promoting vegan blogs giving me an opportunity to express my disagreement! 8-:)

veggiedude said...

This topic is covered in this Dr Greger lecture from 2003:

Bottom line: this can easily be avoided by taking 2,000 mcg of B12 once a week.

Meat eaters (over age 50) would be wise to take 1,000 mcg once a week.

Anonymous said...

Alzheimer disease is a meat eaters disease. I have never heard of a vegan getting it.