6 replies to this topic

[resveratrol_guy]

I posted this thread a while back with the goal of determining what if anything about consuming large amounts of nuts was causing me heavy brain fog which took days to reverse. Manganese, omega-6, and subtle allergic reactions were prime suspects, based on the known science. However, in light of this fascinating discovery relating GLAST to tinnitus of neurological origin, it seemed to me that the main cause may come down to dietary glutamic acid and GLAST status.

It's not much of an exaggeration to say that the neurotransmitter glutamate (which is literally glutamic acid by another name) is the mother of all endogenous excitotoxins. While necessary for proper brain function, excessive amounts can destroy neurons. And before they do, the excitotoxicity itself likely causes sleep deprivation; for these reasons, I now think I have a better explanation for the nut mystery, along with a new strategy for avoiding dementia which costs nothing to implement and augments all the other good habits discussed here on the forum: avoid excessive dietary glutamic acid. This would be especially important for people with the GLAST mutations alluded to in the article. (Unfortunately I don't have specific SNPs, so post them if you do.)

Over many years, I found that the memory impairment capacity of various nuts is, worst to least: almonds, cashews, walnuts, and macadamias. As you can see below, that ranking correlates with their glutamic acid content (nutritiondata.com). I also wondered why swiss cheese would give me headaches, whereas I could tolerate more of other cheeses; the answer seems to be high glutamic acid. I stopped eating cheese several months ago when I discovered that cheese consumption, though associated with lower rates of cardiovascular failure, is associated with the highest dementia rates in the world (e.g. France and Scandanavia); this could be biased by longer lifespans, but the Japanese seem much better off in this regard, despite their long lives.

It would seem that changes in tinnitus level are a proxy for the amount of free glutamate in the brain, assuming that it's neurological as opposed to mechanical in origin. Note that salicylate tends to increase tinnitus, presumably due to GLAST suppression, despite the well established connection between aspirin consumption and reduced risk of dementia. In the absence of aspirin, then, I think the primary driver of tinnitus is dietary glutamic acid intake. There is no GLAST drug or gene therapy under development, which in practice means that controlling tinnitus comes down to dietary glutamic acid and aspirin intake. (I still think aspirin is helpful against dementia, but pausing intake for a while could allow one to calibrate glutamic acid effects.)

So I think the nut connection is: Eat nuts -> upregulate glutamate -> inihibit sleep -> kill neurons. This process would be amplified with mutations that inhibit GLAST from doing its job, which would seem to account for the bifurcation of the population between those who suffer the mental effects of eating nuts, and those who do not.

For those who would protest that nuts are nutritious, I would counter that the connection between eating a small handful of nuts per day, and living several years longer, comes down to selenium, zinc, and/or small ketogenic effects. There are other ways to achieve the same benefits without ingesting the glutamic acid and allergenic substances in nuts.

Below is the glutamic acid content in mg per 100g of various foods, which are raw or canned unless otherwise stated. Note how the Okinawans load up on sweet potatoes, while the French load up on cheese, in light of the difference in their dementia rates despite having similar lifespans. And for all those years, we thought it was the cholesterol!

soy beans, dry roasted 7668
almonds 6811
swiss cheese 5704
peanut 5391
pork 5642
cashew 4506
walnut 2816
chicken 2611
shiitake 2579
herring 2447
macadamia 2267
edamame (soy) 2165
whey 2096
pecan 1993
egg yolk 1970
chocolate, 100% dark 1870
egg white 1550
blackeye peas 897
peas 604
broccoli 542
brown rice 526
tomato 431
beet 428
butter 404
avocado 321
cucumber 196
sweet potato 155
watermelon 97
celery 90
olive oil 0
 

Don't get me wrong. Some foods, such as raw egg yolks loaded with DHA, are worth eating despite the glutamic acid content.

Edited by resveratrol_guy, 03 September 2016 - 07:40 PM.

[resveratrol_guy]

It also looks like zinc is intimately connected with glutamate metabolism in the brain (here and here). I've always wondered why 25 mg/d of zinc gluconate (not glutamate!), an organic salt, should have such a noticeable effect on my memory performance. A friend of mine tried several of my nootropic recommendations, each of which failed, only to find that zinc seemed to work well for him as well. There is such a thing as too much zinc, but this gives new insights into its mechanism of action in cognition, apart from its helpful competition with Cu(2+) in the gut.

 

There are plenty of other compounds which mitigate excitotoxicity, e.g. honokiol and Longvida, but diet and zinc intake would seem to be cheapest easiest place to attack this problem, if you suffer from it due to GLAST mutations.

Edited by resveratrol_guy, 03 September 2016 - 09:06 PM.

[ceridwen]

Zinc doesn't help me. Nor have I noticed a correlation between tinnitus and eating nuts. Must be triggered by something else in me.

[Darryl]

Glutamate is in all whole food proteins. Nuts aren't remotely close to the highest concentrations of glutamate, looking at equicaloric servings.

 

Nuts are consistently associated with better cognitive status.

 

Hart et al, 2013. Nutritional status of older adults with and without dementia. Proceedings of the Nutrition Society, 72(OCE4), p.E247.

Food-based analyses suggested that adults with dementia were less likely to consume fruit and nuts and seeds (p < 0.007) and more likely to consume sugars and snacks (p<0.001) than controls. These differences remained significant, with the exception of fruit, when analysed within healthy weight adults only (p < 0.005).

 

O'Brien et al, 2012. Long-term consumption of nuts in relation to cognitive function and decline in women. Alzheimer's & Dementia, 8(4), p.P314

Higher total nut intake over the long-term was associated with modestly better cognitive performance at older age across all cognitive outcomes (e.g., ptrend < 0.02 for global composite score combining all cognitive tests), after adjusting for multiple potential confounders.

 

Nooyens et al, 2011. Fruit and vegetable intake and cognitive decline in middle-aged men and women: the Doetinchem Cohort Study. Br J Nutr, 106(5), pp.752-761.

Higher intake of nuts was associated with better cognitive function at baseline in all domains (all P-trend > 0.01)

 

Note that glutamate is also the source of the primary inhibatory neurotransmitter GABA, via a 1-step catalysis by glutamate decarboxylase. Assuming one is replete in its cofactor B6, and doesn't gorge on MSG in processed foods, the body can handle whole food sources.

 

 

[aribadabar]

You can't seriously claim that eggs are healthier than nuts.

In all population studies, and particularly the large PREDIMED one, the regular nut consumption (in moderate doses) was positively correlated to better health outcomes.

[resveratrol_guy]

My point here is more about immoderate nut consumption. When I was eating nuts regularly (because I thought they were a "safe" ketogenic food), I would down anywhere from 100 g to 300 g per day. At night, my brain wouldn't shut down, and at best, I'd get an hour of actually decent sleep. But I never had this problem with meat, despite its comparably high glutamate content. This probably comes down to differences bioavailability, and the simple fact that most people find it more entertaining to stuff their faces with cashews, than meat. And more importantly, differences in GLAST status: if it's working properly, you can dispose of the excess glutamate and feel fine; if it's broken, you end up like me after eating a pound of almonds. I'm not making this up. The brain fog was obvious and lasted a few days after I stopped eating nuts.

Could it be something else in nuts that just happens to correlate with glutamate levels? Sure, but what? After a year, no one has offered a simpler explanation. It's not the fat causing ketogenic thermogenesis; I can drink lots of olive oil and sleep fine.

The whole point is that if you think you have this problem, then following a low-glutamate diet (read: low-bioavailable-glutamate diet) might result in substantial improvements. Based on experience, the difference should be obvious in less than a week. I've repeated this hundreds of times, not really understanding why it worked.

Having said that, it may be inaccurate to pin the blame on dietary glutamate, on account of bioavailability and other variances among foods, but the tinnitus study directly correlates excessive glutamate in the brain to excitotoxicity in a manner which is noninvasively measurable by an external observer. To me, that implies that targetting excess brain glutamate is a viable strategy against cognitive decline. The cheapest and easiest way to do that is via diet. The most efficient way would be via pharmaceutical drugs which have not yet been invented.

As to eggs, I do actually think that eggs are more nutritious than nuts, gram for gram. After all, they contain all the ingredients necessary to create a bird. They're also the #1 most common food among the longest lived people, which I could identify in the literature. But there are ways to obtain the nutrition in both foods via alternatives, so neither is vital to survival.

 

"Assuming one is replete in its cofactor B6, and doesn't gorge on MSG in processed foods, the body can handle whole food sources." -- OK, so are you saying that if I can supply enough cofactor B6, I should be able to cancel the glutamate explosion due to a nut binge? How would I ensure that supply? (Man, that would be great, but I'm not optimistic...)

Edited by resveratrol_guy, 04 September 2016 - 07:54 PM.

[ceridwen]

The thing that really seems to be making a difference at reducing my tinnitus is mega doses of Vitamin C.