Betaine hcl is a metabolite of choline, and is also known as trimethylglycine or TMG. It has three methyl groups. DMG has two methyl groups. Betaine works by donating methyl  (CH3) groups and has the ability to convert homocysteine to methionine.
   A methyl donor is simply any substance that can transfer a methyl group, a carbon atom attached to three hydrogen atoms, to another substance. Many important biochemical processes rely on methylation, including the metabolism of lipids, neurotransmitters, and DNA. Scientists suspect that adequate methylation of DNA can prevent the expression of harmful genes, such as cancer genes. It’s quite likely that our body’s ability to methylate declines with age, potentially contributing to the aging process, and therefore supplementation is an interesting potential in terms of health benefits.

Source Naturals - Buy Betaine HC1, 650 mg, 180 Tablets

According to the manufacturer: In the stomach, hydrochloric acid converts pepsinogen to pepsin, an enzyme that breaks down protein. Pepsin breaks down proteins into smaller, more easily absorbed substances. As people age, hydrochloric acid secretion may be reduced, which can result in decreased levels of pepsin. Without proper pepsin levels, the body has a difficult time digesting food. Betaine hydrochloride is used as a supplemental source of hydrochloric acid, which can be utilized by the stomach to produce pepsin. The combination of betaine hydrochloride and pepsin provide an excellent stomach tonic.

Supplement Facts
Betaine Hydrochloride - 650 mg each pill
Pepsin 1: 3000 - 165 mg
You can buy Betaine hcl at health food stores.

Research indicates
Betaine lowers homocysteine levels.
Betaine hydrochloride has been found to protect liver cells from toxins.
It is a safe nutrient that leads to a significant biochemical and histological improvement in patients with nonalcoholic steatohepatitis (NASH).

Alzheimer's disease
An open-label, 24-week pilot study of the methyl donor betaine in Alzheimer disease patients.
Alzheimer Dis Assoc Disord. 2001.
We investigated the safety and tolerability of betaine in patients with Alzheimer disease. The rationale was to decrease serum homocysteine levels and to increase brain methionone and S-adenosylmethionine, both of which might delay disease progression. Eight patients with probable mild AD received oral betaine (3 g twice daily) for 24 weeks. All patients were on donepezil 10 mg/day for at least 3 months before entry and throughout the study. One patient suffered a myocardial infarction and withdrew after 6 weeks. Another patient, who completed the trial, experienced diarrhea and prostatitis. Four of the 7 patients who completed the trial were rated on the Clinician's Global Impression of Change as worse after 24 weeks.
   Comments: Here's an example of lack of understanding of proper nutrient dosage by researchers. They used 6 grams of betaine a day which can make any condition ,or anyone who is healthy, worse off due to overstimulation. Researchers should first take supplements themselves at different dosages before doing a study and wasting everyone's time, money, and coming up with unhelpful data.

Homocysteine
Low dose betaine supplementation leads to immediate and long term lowering of plasma homocysteine in healthy men and women.
J Nutr. 2003.
Wageningen Centre for Food Sciences and Wageningen University, Wageningen, the Netherlands.
High plasma homocysteine is a risk for cardiovascular disease and can be lowered through supplementation with 6 g/d of betaine. However, dietary intake of betaine is approximately 0.5-2 g/d. Therefore, we investigated whether betaine supplementation in the range of dietary intake lowers plasma homocysteine concentrations in healthy adults. Doses in the range of dietary intake reduce fasting and postmethionine loading plasma homocysteine concentrations. A betaine-rich diet might therefore lower cardiovascular disease risk.

Liver disease
How long does it take after starting betaine supplement use before noticing liver benefits?
    There are a number of different liver conditions, and each with its own severity, so it is not easy to know or make predictions.

Libido enhancement
Does betaine hcl enhance sexual libido effects as does tongkat ali herbal extract?
    We have not seen any mention in research papers of it having this effect.

Would it be safe to use yohimbe herb bark along with betaine?
    We have not seen studies with these pills together with herbs used for erectile enhancement but low doses should be acceptable.

Side effects, danger
When I take betaine hcl supplements, I get a headache and tighter shoulders. I know my liver is very congested, inflammation. I read this info on betaine. "A dosage of 2,000 - 4,000 mg (2 - 4 grams) per day of the Trimethylglycine (TMG) form is commonly recommended for people with pre-existing Liver Disease. Orally-administered Betaine is rapidly absorbed. Peak concentrations are reached in less than one hour after its oral ingestion. The elimination half-life of orally-administered pills is approximately 14 hours after a single dose. This half-life increases to 41 hours after five days of daily doses. Following its ingestion, it is converted to Dimethyl Glycine (DMG) within the Liver. Plasma DMG levels increase significantly after betaine ingestion. Approximately 4% is excreted unchanged via the Kidneys (indicating that the remaining 96% is metabolized within the body to form other compounds such as DMG)."
     Often the side effects of supplements, such as betaine, are due to the high dosages used. Taking a portion of the amount normally taken can eliminate or minimize the side effects.

Content in food
Do you have any idea how much anhydrous betaine can be found in beet root powder?
    Good question. We don't know.

Different forms
Would you happen to know if a betaine glucuronate supplement is sold in the United States? I've only been able to locate the hydrochloride which, unfortunately, irritates my stomach.
    We have not seen betaine glucuronate supplement for sale.

Dosage
I have had candida for very long time and it has been causing chronic inflammation in my liver, stomach, intestines, I have not been able to recover and have tried many candida treatments in the last 10 years. I recently discovered that I have a gastroparesis obviously a result from the long-term gastritis caused by it. But every time I do treatment or the candida I just get worse and never get past the die off. In fact treating the candida just makes my gastroparesis symptoms worse. I'm pretty sure my gastroparesis is accompanied by low stomach acid. When I take betaine hydrochloride even at six tablets I still don't get any heartburn. In fact I haven't had heartburn for a few years now as my condition got worse. What is a safe dosage for the teen hydrochloride when doing a challenge? I'm pretty sure I have a severe stomach acid deficiency but what is the maximum dose of hydrochloride a person can take? I would like to keep increasing until I get heartburn so I can back off one and take the required amount. The tablets are 600 mg, I don't experience any warming sensation or heartburn even at six pills. One other question I have is if taking betaine hydrochloride would it affect your blood pH if you're trying to keep or raise it in alkalinity?
    We have not seen any safety studies with betaine hcl in terms of maximum dosage and how it influences blood pH.

Combination with other dietary products
Can a bilberry supplement be taken with betaine hcl? What about bacopa herb that works for mental improvement?
    If the dosages are low, yes.