A glass of wine with dinner, a beer with friends, a toast with sparkling wine: alcohol is part of many everyday situations. Less well known is that regular drinking affects the balance of several B vitamins. What happens to vitamin B1, vitamin B12 and folate – and when does it become relevant?
At a glance
- What it's about: A glass of wine, a beer with friends – what does regular drinking do to vitamin B1, vitamin B12 and folate?
- Possible causes: Alcohol inhibits absorption in the gut, alters storage in the liver and can increase excretion; a one-sided diet often adds to this. Amount and duration are what matter.
- What you can do: Have tingling or persistent tiredness checked by a doctor; sudden confusion, an unsteady gait or disturbed eye movements are an emergency. If you want to drink less, counselling services and your GP practice can help.
- What can be measured: Folate and vitamin B12 from capillary blood; vitamin B1 is measured in whole blood by your doctor, often together with a blood count and liver values – as building blocks, not a diagnosis.
What alcohol does to B vitamins in the body
B vitamins are water-soluble. The body absorbs them through specific transporters in the small intestine, stores some only to a limited extent and excretes excess via the kidneys. Alcohol can interfere at several of these points: it inhibits transport pathways in the intestinal lining, alters storage in the liver and can increase excretion (PubMed 37049411) (PubMed 21749321).
Diet adds to this: alcohol supplies energy but hardly any vitamins or protein. People who drink a lot often eat less or less varied food. A review therefore describes isolated nutrient gaps such as vitamin B1 or zinc as typical with sustained heavy drinking (PubMed 38193343). With occasional, light drinking and a balanced diet these effects play a much smaller role.
Alcohol and vitamin B1: why alcohol-related B1 deficiency is taken so seriously
The body needs vitamin B1 (thiamine) to turn carbohydrates into energy – nerve cells and the heart depend on it in particular. Alcohol reduces thiamine absorption in the gut, and the liver stores it less well and converts it less well into its active form (PubMed 37049411) (PubMed 30281514). Because the body only has small reserves, sustained heavy drinking combined with a poor diet can lead to vitamin B1 deficiency.
The most serious consequence is Wernicke's encephalopathy, an acute brain disorder. According to autopsy studies it is often missed because symptoms do not always appear typically (PubMed 17434099). Classic signs are confusion, an unsteady gait and abnormal eye movements – but often only some of them are present. Untreated, it can progress to a lasting memory disorder (Korsakoff syndrome) (PubMed 30281514). If such signs appear suddenly, it is an emergency: call 112 (the European emergency number). Treatment is a medical matter, not something to try on your own.
Does alcohol deplete vitamin B12? What studies show
Vitamin B12 is stored in the liver for years, so a deficiency usually develops slowly. A controlled study in 53 postmenopausal women shows that even moderate drinking can affect B12: at 30 grams of alcohol per day – roughly two small glasses of wine – serum B12 fell by an average of 5 percent after eight weeks compared with the alcohol-free phase (PubMed 15138463). A small effect, but an indication that alcohol and B12 are linked.
With long-term heavy drinking, further factors come into play, such as changes in the stomach lining, a one-sided diet and liver disease (PubMed 38193343). Alcohol-related B12 deficiency is therefore mainly a consideration with sustained high intake.
Alcohol and folate: absorption, storage, excretion
Folate is important for cell division and blood formation. The link between alcohol and folate is particularly well studied: chronic drinking inhibits the folate transporter in the gut, reduces uptake into the liver and increases excretion via the kidneys (PubMed 12163694). Together with a low-folate diet, this can lead to folate deficiency. In the eight-week study of moderate drinking, however, folate levels remained unchanged (PubMed 15138463) – here too, amount and duration matter.
Alcohol-related vitamin deficiency: how it may show and why measuring helps
B-vitamin deficiencies often appear late and non-specifically. Textbook knowledge includes:
- Vitamin B1: non-specific at first, later abnormal sensations or numbness in the feet; in severe cases the neurological signs described above (PubMed 30281514).
- Vitamin B12 and folate: anaemia with enlarged red blood cells, visible as a raised MCV in the blood count. Alcohol itself can, however, enlarge red blood cells – so an abnormal blood count alone does not tell you the cause (PubMed 19202968).
Tiredness or tingling have many possible causes. Such complaints should be checked by a doctor; only blood values show whether a deficiency is present. Which values are worth considering is covered in the overview Which blood tests should I get?
Measure instead of guessing: The Vitamin Check Basic measures folate and vitamin B12 – plus vitamin D, vitamin E and coenzyme Q10 – from a few drops of capillary blood that you collect at home. Vitamin B1 is not included. If your main concern regarding alcohol is vitamin B1, talk to your doctor: thiamine is measured in whole blood, often together with a blood count and liver values.
When alcohol becomes difficult: finding support and talking to professionals
Sometimes the question about vitamins leads to a bigger one: how much do I actually drink, and how easy is it for me to go without? If you would like to talk about it – for yourself or for someone close to you – there are anonymous and confidential services:
- German addiction and drug hotline (Sucht & Drogen Hotline): 01806 313031 (daily 8 am to midnight, €0.20 per call from landline and mobile; German-language service)
- TelefonSeelsorge (crisis line, Germany): 0800 111 0 111 or 0800 111 0 222 (free, around the clock)
- Local addiction counselling services and your GP practice
If you regularly drink larger amounts and want to cut down or stop, have this supported by a doctor. Topics to discuss with professionals include:
- How much and how often do I drink, and what does my diet look like?
- Does it make sense to measure vitamin B1, B12, folate, blood count and liver values?
- How should abnormal values be interpreted when alcohol itself can change lab results?
- What kind of support suits me if I want to drink less?
You can talk to your doctor, a naturopathic practitioner or the ORY expert team.
In brief
- Alcohol can affect the absorption, storage and excretion of vitamin B1, B12 and folate.
- Marked deficiency mainly affects people with sustained heavy drinking and a poor diet.
- Severe vitamin B1 deficiency can lead to a neurological emergency – sudden confusion or unsteadiness need immediate medical care.
- Even moderate drinking slightly lowered B12 levels in one study; folate was unchanged there.
- Folate and B12 can be measured; vitamin B1 is measured by your doctor.
Frequently asked questions
Can alcohol cause vitamin B1 deficiency?
Yes, mainly with sustained heavy drinking. Alcohol reduces thiamine absorption in the gut and storage in the liver, and dietary intake is often low as well (PubMed 37049411) (PubMed 38193343).
Does alcohol deplete vitamin B12?
Alcohol does not "remove" B12 directly, but it can lower levels. In a controlled study, B12 fell slightly after eight weeks at 30 grams of alcohol a day (PubMed 15138463). With long-term heavy drinking, diet, stomach and liver add to this (PubMed 38193343).
How are alcohol and folate linked?
Chronic drinking inhibits folate absorption in the gut and liver and increases excretion via the kidneys (PubMed 12163694). Folate deficiency mainly develops with heavy drinking combined with a low-folate diet.
How can you tell if you have an alcohol-related vitamin deficiency?
Only from blood values. Complaints such as tiredness or tingling are non-specific, and alcohol can itself change the blood count (PubMed 19202968). That is why assessment belongs with a doctor.
What is Wernicke's encephalopathy?
An acute brain disorder caused by vitamin B1 deficiency. Possible signs are confusion, unsteady gait and abnormal eye movements, often not all at once (PubMed 17434099). With such signs: call 112.
Can I have vitamin B12 and folate measured myself?
Yes. The Vitamin Check Basic covers folate and vitamin B12 from capillary blood. Vitamin B1 is not included; your doctor can measure it.
Where can I find help if I want to drink less?
From the German addiction and drug hotline (Sucht & Drogen Hotline): 01806 313031 (daily 8 am to midnight, €0.20 per call from landline and mobile; German-language service), local addiction counselling services and your GP practice. Conversations are confidential.
Important note: This article does not replace medical advice, diagnosis or treatment. It is for general information only. If your symptoms are persistent or severe, please contact your doctor. Do not stop a prescribed medication without talking to your doctor first.
Sources
- Butts M et al. The influence of alcohol consumption on intestinal nutrient absorption: a comprehensive review. Nutrients. 2023. PubMed 37049411
- Said HM. Intestinal absorption of water-soluble vitamins in health and disease. Biochem J. 2011. PubMed 21749321
- Jophlin L, Liu TY, McClain CJ. Nutritional deficiencies in alcohol use disorder/alcohol-associated liver disease. Curr Opin Gastroenterol. 2024. PubMed 38193343
- Chandrakumar A, Bhardwaj A, 't Jong GW. Review of thiamine deficiency disorders: Wernicke encephalopathy and Korsakoff psychosis. J Basic Clin Physiol Pharmacol. 2018. PubMed 30281514
- Sechi G, Serra A. Wernicke's encephalopathy: new clinical settings and recent advances in diagnosis and management. Lancet Neurol. 2007. PubMed 17434099
- Laufer EM et al. Effects of moderate alcohol consumption on folate and vitamin B12 status in postmenopausal women. Eur J Clin Nutr. 2004. PubMed 15138463
- Halsted CH et al. Metabolic interactions of alcohol and folate. J Nutr. 2002. PubMed 12163694
- Kaferle J, Strzoda CE. Evaluation of macrocytosis. Am Fam Physician. 2009. PubMed 19202968
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