1

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Diet Sodas cause Depression. Aspartame shown to lower Serotonin?

Answered on September 12, 2014
Created July 22, 2013 at 6:56 AM

truthstreammedia.com/food-for-thought-aspartame-and-ssris/

rense.com/general80/heath.htm

I know there's alot of negative things being tossed around about diet drinks, most of which don't seem to be extremely conclusive. However, I've been researching aspartame biochemistry and it turns out aspartame breaks down into phenylalanine (and methanol), which competes with tryptophan, the precursor for serotonin, for the same channel through the blood-brain barrier into the central nervous system. Excessive consumption of aspartame (isolated phenylalanine in big doses, unnaturally) is now being shown to reduce serotonin levels leading to depression, anxiety and sleep disorders (serotonin -> melatonin).

Anyone notice similar problems with diet soda consumption or after quitting? I used to be a 2L/day guy on Diet Cokes and sugar free sodas. I've dropped it recently in medical school and I seem to see improvement but I'll need a few weeks to re-confirm. Share your thoughts!

Also, reduced serotonin leads to carb/sugar binging and cravings. Do you that's why people who drink diet cokes tend to eat unhealthy foods? Maybe it's not simply because they think they can cheat more with a zero calorie drink

Edit: For a long time, I knew that aspartame breaks down into phenylalanine, and since Phe is an amino acid I figured its all-natural. Not so fast after I did some more digging. Phe competes with tryptophan through the same channel into the brain. However, it turns out that tryptophan (precursor to serotonin) is mostly bound by albumin proteins in the blood whereas the other 19 amino acids are more free in plasma. During a meal, insulin is secreted and drives the rest of the amino acids into body/muscle cells leaving tryptophan alone in the blood, because it remains bound to albumin. This selectively increases tryptophan delivery into the brain with no competition from other amino acids (being bound to albumin has no effect on tryptophan delivery into brain, unlike to muscle cells). Hence this is why we all know carbs to selectively raise serotonin levels: as other AA's are cleared from blood into muscle cells, tryptophan can cross the blood brain barrier more readily.

The problem with diet soda is you not only get a giant bolus of phenylalanine into the blood, but diet soda triggers little insulin secretion (if any), allowing large amounts of isolated phenylalanine to stay in the plasma instead of going to muscle cells. It now can out compete tryptophan through their common channel into the brain, and causing low serotonin.

72cf727474b8bf815fdc505e58cadfea

on July 23, 2013
at 08:59 PM

@DH In that study (on rats), reduced serotonin was found in the medium-dose group -- 133mg/kg/day, equivalent to a 130lb (60kg) human drinking 44 cans of soda every day for a month -- and the high-dose group, equivalent to 216 cans per day. A reduction was NOT found in the low-dose group (equivalent to 4 cans per day). In fact, that group showed an INCREASE in serotonin (not indicated whether it's significant or not).

Cc69a51b427eaad36251cce9dcca4d3a

(1074)

on July 23, 2013
at 08:53 PM

if u do a quick search of aspartame on pubmed you'll find a good # of studies regarding metabolic syndrome or about phenylalanine. the truth is this is all new research bc when FDA first approved of aspartame it didn't go thru human clinical trials, only mouse. its ironic that we basically accepted aspartame into our diets without rigorous clinical data, but now we won't give it up unless there's rigorous clinical data to the contrary

Cc69a51b427eaad36251cce9dcca4d3a

(1074)

on July 23, 2013
at 08:45 PM

@matt you happy now? http://www.ncbi.nlm.nih.gov/pubmed/2442082

72cf727474b8bf815fdc505e58cadfea

on July 23, 2013
at 03:41 PM

@dh Good point about the lack of competing amino acids. Still, I'm skeptical. Can you provide any citations you mentioned?

32f5749fa6cf7adbeb0b0b031ba82b46

(41757)

on July 23, 2013
at 12:23 PM

Always suspect when anti-aspartame folks claim there are Pubmed entries that support their position, but never link to any.

Cc69a51b427eaad36251cce9dcca4d3a

(1074)

on July 23, 2013
at 06:50 AM

i will also add that many of us doing Paleo or on PH are sick and come from imbalanced physiological backgrounds. if 1-2 cans of diet coke can tip the balance of serotonin negatively, it may be good reason to avoid it entirely as many of us have screwed up dopamine/serotonin levels to begin with hence our cravings and fatigue etc

Cc69a51b427eaad36251cce9dcca4d3a

(1074)

on July 23, 2013
at 06:47 AM

the problem is that its isolated Phe whereas natural protein sources i.e. meat have 20 AA's for Phe to compete with to get into the blood brain barrier. 90mg of Phe without any competing AA's can certainly tip the balance of brain serotonin, there are Pubmed studies to confirm this. not to mention many diet coke addicts drink 2-3L of this everyday, not 12oz

72cf727474b8bf815fdc505e58cadfea

on July 23, 2013
at 04:02 AM

I should add that there are some people who drink truly massive amounts of diet soda, and it's not impossible that they could be significantly increasing their phenylalanine intake. But I don't think it's an issue for most people.

Fab409ac4a30957e3ed508514f7bff02

(295)

on July 23, 2013
at 02:16 AM

Very interesting! Thanks for the info!

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4 Answers

4
72cf727474b8bf815fdc505e58cadfea

on July 22, 2013
at 11:01 PM

This seems very unlikely.

A can of diet soda contains about 180mg of aspartame. Aspartame is a phenylalanine/aspartic acid dipeptide, so it will yield around 90mg of phenylalanine. According to cronometer, yesterday I ate 116g of protein from animal and dairy sources, and got a total of 5.2g of phenylalanine. Unless you have PKU, the amount naturally occurring in your diet is many times higher than what's in a soda.

Even if we assume that the phenylalanine from aspartame is released into your system more quickly than it is from real food, it's still a tiny amount. There's as much phenylalanine in one bite of hamburger as in an entire can of diet soda. (back-of-envelope calculation; I used 15g of 80% lean meat).

Finally, phenylalanine contributes to the production of dopamine and norepinephrine. For people with some types of depression, increases in those neurotransmitters are more helpful than an increase in serotonin.

Cc69a51b427eaad36251cce9dcca4d3a

(1074)

on July 23, 2013
at 08:53 PM

if u do a quick search of aspartame on pubmed you'll find a good # of studies regarding metabolic syndrome or about phenylalanine. the truth is this is all new research bc when FDA first approved of aspartame it didn't go thru human clinical trials, only mouse. its ironic that we basically accepted aspartame into our diets without rigorous clinical data, but now we won't give it up unless there's rigorous clinical data to the contrary

32f5749fa6cf7adbeb0b0b031ba82b46

(41757)

on July 23, 2013
at 12:23 PM

Always suspect when anti-aspartame folks claim there are Pubmed entries that support their position, but never link to any.

72cf727474b8bf815fdc505e58cadfea

on July 23, 2013
at 04:02 AM

I should add that there are some people who drink truly massive amounts of diet soda, and it's not impossible that they could be significantly increasing their phenylalanine intake. But I don't think it's an issue for most people.

Cc69a51b427eaad36251cce9dcca4d3a

(1074)

on July 23, 2013
at 06:50 AM

i will also add that many of us doing Paleo or on PH are sick and come from imbalanced physiological backgrounds. if 1-2 cans of diet coke can tip the balance of serotonin negatively, it may be good reason to avoid it entirely as many of us have screwed up dopamine/serotonin levels to begin with hence our cravings and fatigue etc

Fab409ac4a30957e3ed508514f7bff02

(295)

on July 23, 2013
at 02:16 AM

Very interesting! Thanks for the info!

Cc69a51b427eaad36251cce9dcca4d3a

(1074)

on July 23, 2013
at 06:47 AM

the problem is that its isolated Phe whereas natural protein sources i.e. meat have 20 AA's for Phe to compete with to get into the blood brain barrier. 90mg of Phe without any competing AA's can certainly tip the balance of brain serotonin, there are Pubmed studies to confirm this. not to mention many diet coke addicts drink 2-3L of this everyday, not 12oz

72cf727474b8bf815fdc505e58cadfea

on July 23, 2013
at 03:41 PM

@dh Good point about the lack of competing amino acids. Still, I'm skeptical. Can you provide any citations you mentioned?

Cc69a51b427eaad36251cce9dcca4d3a

(1074)

on July 23, 2013
at 08:45 PM

@matt you happy now? http://www.ncbi.nlm.nih.gov/pubmed/2442082

72cf727474b8bf815fdc505e58cadfea

on July 23, 2013
at 08:59 PM

@DH In that study (on rats), reduced serotonin was found in the medium-dose group -- 133mg/kg/day, equivalent to a 130lb (60kg) human drinking 44 cans of soda every day for a month -- and the high-dose group, equivalent to 216 cans per day. A reduction was NOT found in the low-dose group (equivalent to 4 cans per day). In fact, that group showed an INCREASE in serotonin (not indicated whether it's significant or not).

2
96440612cf0fcf366bf5ad8f776fca84

(19413)

on July 22, 2013
at 10:31 AM

Sounds like a nice vicious cycle which causes the victims of these products to be addicted to them, not in the same sense that caffeine is addictive, but in fooling them to keep buying the very thing that depleted their serotonin levels in the first place.

0
A1b311ad17853e7d92151c5f59520677

on December 21, 2013
at 04:18 PM

My experience is anecdotal, but powerful, at least for me.

I suffered from severe depression for twelve years (1997 - 2005). The last six years I was on antidepressants. In order, I tried prozac, zoloft, lexapro, and finally wellbutrin, always looking for option that had the least side effects (especially on libido).

I've always exercised frequently and began to notice that my knees would hurt terribly after 30 minutes on the stair stepper. I also developed bones spurs on both elbows. I thought it was probably age. Then I read an article that described how the phosphoric acid in diet drinks leaches calcium out of your bones. Since I was drinking 3 cans of diet coke per day, I thought I'd give it up to see if it made a difference. So, I gave up the diet cokes cold turkey. I had none of the supposed addiction withdrawals that some people claim.

A few months after I gave up the diet coke, I noticed that my depression was lifting. Six months post diet coke, I was off my meds completely, and I have not taken any meds for seven years, now. Also, my joint pain did go away and I exercise much more comfortably.

I am an evangelist against all soft drinks, especially the diet varieties. When I read the 2013 stories about diet soft drinks and depression, I was already there.

0
0a050e0e95776a2878d364aa6e47a743

on July 23, 2013
at 02:32 PM

Would love to hear thoughts on aspartame and migraine. At the adivise of a doc in 1998, I quit all artificial sweeteners and have been migraine free ever since...except once after I had a mint with aspartame ONE TIME. I guess I am just on the low end of food/additive sensitive folks, tho.

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