Is fresh squeezed lemon juice alkaline or acidic?

[Gustav3Y]

Is fresh squeezed lemon juice alkaline or acidic for the body?

Considering that it increases the sensitivity in my teeth and it has citric acid I am not quite sure why people say it is "alkalizing the body"
Isn't lemon juice increasing actually stomach acidity?

I have been drinking a bit these days and I seem to have developed some sharp chest pains that can get even sharper if there is a burp.
But there is no burning sensation or throat reflux.
It seems others can feel this too:

After lemon water, I feel some pain in my chest. Why?

Answer (1 of 3): Disclaimer: This is not meant to replace seeing your physician for these complaints, as this could be cardiac related or represent a serious problem. Having said that, read below… I would say your digestion system has too much upward movement. Lemon water is used to increase ac...

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Not quite sure what should I take to try to mediate the effect, some sodium bicarbonate maybe?
All this "lemon is alkalizing the body" seems to make doctors also think the same, so I am getting confused considering how acidic it is.

 

[Gustav3Y]

Well I have tried just a bit of sodium bicarbonate today around 300mg and it pretty quickly helped with the chest stabs.
I was kind of avoiding it because it can get me sleepy and in active.

 

[retroactive]

Its both apparently. its acidic in its normal form. But the acid/alkaline diet folks maintain that when it is fully broken down and metabolized that it is an alkaline. This is plausible.

 

[Gustav3Y]

It is quite interesting because who could say it is alkaline for their stomach and esophagus like sodium bicarbonate is?
Do people take lemon juice when they have heart burn? I know sodium bicarbonate helps.
I say this because esophagus and stomach get hit instantly by the lemon juice if there are issues in those areas with high acidity.

 

[yerrag]

It is acidic till it gets into the liver. The liver turns citric acid into H+ and citrate. The citrate is converted by the liver into bicarbonate, and then what comes out is H+ + bicarbonate. The most acidic it gets is as a weak acid, carbonic acid. But as bicarbonate, it is alkaline.

 

[Gustav3Y]

So then it has an acidic effect on the esophagus and stomach at contact, no?

 

[yerrag]

So then it has an acidic effect on the esophagus and stomach at contact, no?

Yes. It's already sour to the taste, that's why we don't drink it like we drink orange juice. We dilute it.

 

[Gustav3Y]

I diluted it also a bit, but I also never drank too much, just from 1 lemon and strained.

 

[Amazoniac]

Lemon juice (somehow) appears to lead to a modest increase in urinary pH.
- In vitro and in vivo study of effect of lemon juice on urinary lithogenesis
- Effect of citrus-based products on urine profile: A systematic review and meta-analysis

Spoiler: Blather (not bladder)

I shower once a month and the toxin is claimed to have a pH between 2-3 units.

- Phenolic content, antioxidant activities and stimulatory roles of citrus fruits on some lactic acid bacteria

- Citric acid - Wikipedia

If we consider a juice that has a pH of 2.3, based on the following distribution (standard conditions), it's going to be about 80% as trihydrogen citrate (citric acid) and 20% as dihydrogen citrate.

- Curium(III) citrate speciation in biological systems: A europium(III) assisted spectroscopic and quantum chemical study

Spoiler

In body fluids, the pH will be higher than 7 for the most part. Therefore, all those hydrogens are going to dissociate from the citrate molecule. This should occur already after pancreatic alkalinization (NaHCO3), ionizing them in the following ratios:

H+:citrate−

3:1 * 80% = 2.4
2:1 * 20% = 0.4

Resulting in: H+ 2.8:1.0 citrate−
Potassium is possibly responsible for the difference (3−2.8).​

So, there's a disproportionate amount of hydrogen ions relative to citrate.

Something like this:

H3-Citrate
H3-Citrate
H3-Citrate
H3-Citrate
KH2-Citrate (paired with potassium)​

After alkalinization:

H3-Citrate + 3(NaHCO3) → 3(H+) + Citrate3− + 3(Na+) + 3(HCO3−) → 3(H2CO3) + Na3-Citrate → 3(H2O + CO2) + Na3-Citrate
H3-Citrate + 3(NaHCO3) → 3(H+) + Citrate3− + 3(Na+) + 3(HCO3−) → 3(H2CO3) + Na3-Citrate → 3(H2O + CO2) + Na3-Citrate
H3-Citrate + 3(NaHCO3) → 3(H+) + Citrate3− + 3(Na+) + 3(HCO3−) → 3(H2CO3) + Na3-Citrate → 3(H2O + CO2) + Na3-Citrate
H3-Citrate + 3(NaHCO3) → 3(H+) + Citrate3− + 3(Na+) + 3(HCO3−) → 3(H2CO3) + Na3-Citrate → 3(H2O + CO2) + Na3-Citrate
KH2-Citrate + 2(NaHCO3) → 2(H+) + K-Citrate2− + 2(Na+) + 2(HCO3−) → 2(H2HCO3) + KNa2-Citrate → 2(H2O + CO2) + KNa2-Citrate​

All of those hydrogen ions must be taken up by hydrocraponate, leading to the formation water and crapon dioxide, leaving behind trisodium citrate, some potassium disodium citrate, and then who knows what happens to them. Might be reabsorbed:

- Intestinal gases: influence on gut disorders and the role of dietary manipulations

Spoiler

Dissociate again in red blood cells:

- Transport of Blood Gases | Biochemistry of Blood Elements (presentation #8745635 at slideplayer.com)

Taken up by hemoglobin and reversing it at the lungs to finally be neutralized.

There's no additional sodium input, it was already in the body, it would just return to the system, which is why it must not be responsible for an effect. Crapon dioxide could combine with the pool formed by tissues, as if came from them through cellular respiration, it's going to eventually be converted to hydrocraponate, but with the difference that molecules of hydrocraponate were also used up in the process, so it must also not explain the alkalinization. It's then up to citrate and some potassium ions to alkalinize.

I think that they rationalize that it's through hydrocraponate generation, but I'm still confused by this part. In cellular respiration, full oxidation of dextructose (containing 6 carbons) generates 6 molecules of CO2. We know that at some stage it's split in half, yielding pyruvates (3C + 3C). Tracking one pyruvate molecule, it loses one carbon prior to entering the mitochondria (2C, the acetyl part), which is then used to regenerate citrate. I'm mentioning this because we're adding preformed citrate, so it can only yield 2 CO2 molecules when we stop counting after a cycle.

Source: the internet.

Spoiler

Source: the internet as well, what a coincidence.

On the citrate molecule above, the hydroxyl group that they mentioned on the Wikipedia page is intact, not all representations show that it can also dissociate at a high pH (the Citrate4− on the second figure of this post). I ignored it throughout to avoid text hydrogen overload.

"The pKa of the hydroxyl group has been found, by means of 13C NMR spectroscopy, to be 14.4"​

Returning to the ratio of 2.8:1 (for every hydrogen there's a hydrocraponate ion), if there are 2.8 parts of hydrocraponate ions being used up and citrate yields and adds only 2, I don't know how to explain the observed effect.

3(H+) + Citrate3− + 3(Na+) + 3(HCO3−) → 3(H2HCO3) + Na3-Citrate​

The potassium contribution is modest. However, the dissociation curves are steep, it takes a small increase in juice alkalinity to have more potassium ions pairing citrate.

 

[cs3000]

how much lemon juice would help with digestion?
has pH of 2.2 - 2.6 Sperm immobilizing properties of lemon juice
maybe 25ml in a little water? matching half the common gastric juice amount. not great for the teeth though

 

[ddjd]

It is quite interesting because who could say it is alkaline for their stomach and esophagus like sodium bicarbonate is?
Do people take lemon juice when they have heart burn? I know sodium bicarbonate helps.
I say this because esophagus and stomach get hit instantly by the lemon juice if there are issues in those areas with high acidity.

heartburn is due to low stomach aiditiy

 

[Bozidar]

I heard dr. berg saying it is acidic when you ingest it, and it tastes acidic, but in your body, after it gets digested, it acts alkaline. Dont know if thats true and what exactly he meant by that...