Most beer is built from just four things: water, malted grain, hops and yeast. But look past the label and there is often more going on, from the corn and rice in a mass-market lager to the fish-derived finings that stop some beers being vegan. Here is a plain, honest guide to what is actually in your beer, what each thing does, and what the label may not be telling you. Everything is sourced.
1. The four core ingredients
At heart, beer is an alcoholic drink made by brewing and fermenting the starches in cereal grain, most commonly malted barley[1]. Four ingredients do the heavy lifting:
- Water is the bulk of the drink and its mineral profile shapes the style.
- Malted grain, usually barley, provides the starch that becomes fermentable sugar, plus colour and body[1].
- Hops add bitterness and flavour and act as a natural preservative and stabiliser[1].
- Yeast ferments the sugar into alcohol and carbonation.
That is the whole recipe for a huge number of beers. If you want the step-by-step of how those four become a pint, see our how beer is made guide. From here, we look at everything else that can end up in the glass.
2. Adjuncts: corn, rice, oats and sugar
Barley is not the only grain in the tank. Brewers routinely use other fermentable sources, called adjuncts, to change a beer’s flavour, body, colour or strength[1]. Some are traditional craft choices; others are there to make big-brand lagers lighter and cheaper.
| Adjunct ↕ | What it does ↕ | Where you find it ↕ |
|---|---|---|
| Wheat | Vibrant flavour, better foam and head retention | Witbiers, lambics, wheat beers |
| Oats | Silky mouthfeel, extra creaminess and body | Oatmeal stouts and porters |
| Corn (maize) | Lightens body and flavour, cheaper base | Many mass-market American lagers |
| Rice | Very light, crisp, dry character | Big-brand pale lagers |
| Sugar | Boosts alcohol, adds dryness, tweaks colour | Belgian ales, strong ales |
Tap any column heading to sort.
Adjunct contributions per All About Beer and Wikipedia.
This is why two beers that both say lager can taste worlds apart. A rice or corn adjunct lager is deliberately light and neutral, while an all-malt lager tastes fuller and breadier[2].
3. Is beer vegan? The finings question
Since beer is usually made from barley malt, water, hops and yeast, it is often suitable for vegans and vegetarians[3]. The catch is clarification. To make a hazy beer clear and bright, some brewers add finings, and those can be plant-based or animal-based[3].
The short version: most beer is vegan, but a minority, especially cask ales cleared the old-fashioned way, is not. The only reliable way to know is to check.
4. What else gets added
Mass-market brewing can involve a supporting cast of processing aids and additives that never make it onto the front of the can. Reported examples include betaglucanase (an enzyme used to speed up brewing), propylene glycol alginate (added to stabilise the foam head), and ammonia caramel for colour[5].
None of these are dangerous; they are approved food additives[5]. The real issue is transparency: brewers in the UK and across much of the EU have not been legally required to list every ingredient on the bottle or can[5]. That is exactly why many smaller and craft brewers make a selling point of using only natural ingredients. If you want to know precisely what is in a beer, an independent craft brewery that publishes its recipe is your safest bet.
5. Calories, carbs and protein
Beer is essentially water, alcohol, carbohydrate and a trace of protein. A regular 12 fl oz (355 ml) beer typically lands around 140 to 150 calories with roughly 11 to 12 grams of carbohydrate, while light beers are engineered much lower, from about 64 up to 110 calories with far fewer carbs[4]. Protein is minimal, usually under a gram or so[4].
| Type (12 fl oz) ↕ | Calories ↕ | Carbs (g) ↕ |
|---|---|---|
| Regular lager / ale | 140 to 150 | 11 to 12 |
| Standard light beer | about 110 | about 6.6 |
| Low-carb light beer | about 96 | about 3.2 |
| Ultra-light beer | about 64 | about 2.4 |
Tap any column heading to sort.
Representative figures per Medical News Today’s survey of popular beers. Individual brands vary.
Most of a strong beer’s calories come from the alcohol itself, not the carbs, which is why a higher-ABV craft beer can be more calorific than its carb count suggests.
6. Beer and gluten
Because standard beer is brewed from barley, and sometimes wheat or rye, most beer contains gluten[4]. That matters for anyone with coeliac disease.
There is an important distinction here. A gluten-free beer is made from a naturally gluten-free base such as sorghum or rice, with records kept to prove the ingredients were gluten-free before fermentation[6]. A gluten-reduced or gluten-removed beer starts from barley and is treated to break the gluten down, but there is no reliable test to measure gluten in a fermented drink, so coeliac bodies do not recommend it for people with coeliac disease[6]. If you are coeliac, stick to certified gluten-free beers, not gluten-reduced ones.
Curious how ingredients translate into what you see and taste? Our beer colour guide shows how malt sets the colour, and the beer statistics page has the wider numbers.
7. Frequently asked questions
What are the ingredients in beer?
The four core ingredients are water, malted grain (usually barley), hops and yeast. Many beers also use adjuncts such as corn, rice, wheat, oats or sugar, and mass-market beers may contain approved processing additives. Malt provides sugar, hops add bitterness and preserve, and yeast makes the alcohol.
Why do some beers contain corn or rice?
Corn and rice are adjuncts used mainly in big-brand lagers to lighten the body and flavour and lower cost, giving that crisp, neutral, easy-drinking character. Craft brewers more often use wheat for foam and flavour or oats for a silky mouthfeel. An all-malt beer tends to taste fuller than a rice or corn lager.
Is beer vegan?
Most beer is vegan because it is made from barley malt, water, hops and yeast. However, some brewers clarify beer with finings that can be animal-derived, such as isinglass (from fish) or gelatin. Most modern beer is filtered without animal products, but if it matters, check the brewery’s vegan labelling.
What additives are in mass-market beer?
Reported additives in some mass-market beers include enzymes like betaglucanase to speed brewing, propylene glycol alginate to stabilise the foam, and ammonia caramel for colour. They are approved food additives, but UK and EU brewers have not been legally required to list every ingredient, which is why many craft brewers stress natural ingredients.
How many calories are in a beer?
A regular 12 fl oz beer is usually around 140 to 150 calories with about 11 to 12 grams of carbohydrate. Light beers are much lower, from roughly 64 to 110 calories. Most of a strong beer’s calories come from the alcohol itself rather than the carbs, so higher-ABV beers tend to be more calorific.
Does beer contain gluten?
Yes, most beer contains gluten because it is brewed from barley and sometimes wheat or rye. Certified gluten-free beers are made from naturally gluten-free bases like sorghum or rice. Gluten-reduced beers start from barley and are treated to break gluten down, but they are not recommended for people with coeliac disease because the gluten cannot be reliably measured.
Sources and references
- Wikipedia, Beer (ingredients and brewing)
- All About Beer, The Wide World of Adjuncts
- Wikipedia, Vegetarianism and beer (finings)
- Medical News Today, Carbs in beer: nutrition facts of popular beers
- BBC News, What exactly is in your beer? (additives and labelling)
- National Celiac Association, gluten-reduced or gluten-removed beer
General information, not dietary or medical advice. If you have coeliac disease or a food allergy, follow certified labelling and professional guidance. Please drink responsibly. Reviewed August 2026.
