Is homemade oat milk healthier than shop-bought?

In some ways. It has no enzyme-produced maltose, no phosphate additive, no added oil and no stabilisers, and you control the salt. But shop-bought cartons are fortified with calcium, iodine, vitamin B12, riboflavin and vitamin D, and homemade contains essentially none of those. Which is 'healthier' depends entirely on whether you are getting those nutrients elsewhere.

Why does oat milk have sugar in it if nothing is added?

Commercial oat drinks use enzymes — usually alpha-amylase — to break oat starch into simpler sugars, mostly maltose. That is what makes them taste sweet and pour creamy. The sugar is genuinely not added, but it is created during manufacture, which is why a carton can list around 4 g of sugars per 100 ml with no sugar on the ingredients list. Homemade oat milk skips this step.

Does homemade oat milk have fibre and beta-glucan?

Some, but not much — most of the beta-glucan stays behind in the pulp when you strain. Neither homemade nor shop-bought oat milk is a practical way to get the 3 g of oat beta-glucan a day associated with lowering cholesterol. Eat porridge for that, and use the leftover pulp rather than binning it.

Can children drink homemade oat milk?

Not as a replacement for fortified milk. UK guidance is that plant-based drinks given to children from age one should be unsweetened and fortified with calcium and iodine, and homemade oat milk is neither. Under one year old, plant drinks should not be a main drink at all. Speak to a health visitor or GP rather than working it out from a website.

Is the rapeseed oil in oat milk bad for you?

There is no good evidence that it is, at these amounts. A barista carton is about 3 g of fat per 100 ml, mostly unsaturated. The honest argument for leaving it out of homemade oat milk is calorie control and personal preference, not a proven health risk.

Is homemade oat milk healthier? The evidence

The health case for making your own oat milk usually gets made badly — either as a vague appeal to “no nasties”, or by people who have not looked at what is actually on the carton. It deserves better, because there is a real argument here, and there is also a real catch that most homemade-oat-milk content never mentions.

What is actually in the carton

Here is the full ingredients list of the UK’s benchmark barista oat drink:

Water, oats 10%, rapeseed oil, acidity regulator (dipotassium phosphate), minerals (calcium carbonate, potassium iodide), salt, vitamins (D2, riboflavin, B12).

That is not a frightening list, and nothing on it is there by accident:

Rapeseed oil gives fat for foam structure and mouthfeel. Oats have very little of their own.
Dipotassium phosphate is an acidity regulator. It buffers the milk so hot, acidic espresso does not curdle it — the reason barista milk exists.
Calcium carbonate, potassium iodide, D2, riboflavin, B12 are fortification, added to bring an oat drink somewhere closer to the nutritional job dairy was doing.
Oats 10%, and the thing the list does not show: the enzymes used during manufacture.

The nutrition, side by side

Per 100 ml	Barista carton	Homemade (80 g oats/L)
Energy	59 kcal	~25–35 kcal
Fat	3.0 g	~0.5 g (0.9 g with 1 tsp oil/L)
Carbohydrate	6.6 g	~5 g
— of which sugars	4.0 g	under 1 g
Fibre	0.8 g	~0.3–0.5 g
Protein	1.0 g	~0.5–1 g
Salt	0.10 g	whatever you add
Calcium	120 mg	none
Iodine	22.5 µg	none
Vitamin B12	0.38 µg	none
Riboflavin	0.21 mg	none
Vitamin D	1.1 µg	none

Carton figures are the manufacturer’s published values. The homemade column is an estimate, calculated from oat composition, and it varies considerably with how finely you strain — treat it as a shape, not a measurement.

Two rows do the work in that table. Sugars, where homemade wins. And the bottom five, where it loses badly.

Where homemade genuinely wins

1. Far lower free sugars

This is the most interesting one, and almost nobody knows about it.

Commercial oat drinks are made by treating an oat slurry with enzymes — typically alpha-amylase — which break the starch down into shorter chains and simple sugars, mostly maltose. That is what produces the sweetness and the creamy body people like. No sugar is added, which is why the ingredients list is clean, but around 4 g of sugars per 100 ml are created during manufacture.

Maltose is two glucose molecules, and it is absorbed fast. Oat drinks generally test in the medium-to-high range on the glycaemic index for this reason, and higher than the whole oats they came from.

Homemade oat milk skips the enzyme step entirely. Blend, strain, done — the starch stays largely starch. If you are managing blood glucose, or you simply do not want a sweet drink, that is a meaningful difference, and it applies to the two litres a week going through your coffee as much as anything else.

2. No phosphate additive

Dipotassium phosphate is safe for healthy kidneys, and we are not going to pretend otherwise. But there is a real, evidence-based caveat: inorganic phosphate additives are absorbed far more efficiently than the phosphorus naturally present in food, and renal dietitians routinely advise people with chronic kidney disease to limit them for exactly that reason.

If you have CKD, this is not a marginal point — it is the reason your dietitian tells you to read ingredient lists. Homemade oat milk has no phosphate additive at all.

3. No gums or emulsifiers

The benchmark barista carton does not contain gums, but plenty of oat drinks do — gellan gum being the common one. Research into dietary emulsifiers and the gut microbiome is genuinely interesting, and genuinely early: the strongest signals come from carboxymethylcellulose and polysorbate 80 in animal and laboratory models, while results for gellan gum specifically are mixed, with some studies finding it increases beneficial bacteria.

So the honest position is: this is a reason some people prefer to avoid them, not a demonstrated harm. We would not make it the reason you buy a machine.

4. You control the fat, salt and sweetness

A litre of barista oat milk contains about 30 g of rapeseed oil and a gram of salt. Neither is a problem in itself, and the oil is mostly unsaturated fat. But when you make your own, both are dials rather than fixed values: use oil when the milk is for coffee and skip it when it is for porridge, salt to taste, and sweeten nothing.

Homemade also lands at roughly half the calories of a barista carton, which for someone drinking 150 ml in each of three lattes a day is around 100 kcal a day of difference.

5. It is not an ultra-processed food

Homemade oat milk is oats, water and a blender. Whatever you make of the ultra-processed food literature — and the strongest evidence there is observational — a jug of blended oats sits outside the argument entirely.

Where the carton wins, decisively

Fortification. This is the part that gets left out of most “ditch the carton” content, and it is the most important thing on this page.

A fortified oat drink delivers calcium, iodine, vitamin B12, riboflavin and vitamin D. Homemade oat milk delivers none of them. If oat milk is genuinely replacing dairy in your diet, you have quietly removed a significant source of all five.

Iodine deserves particular attention in the UK, where dairy is one of the main dietary sources, and it matters most in pregnancy. Dietary modelling has found that replacing cow’s milk with unfortified plant drinks cuts intakes of calcium, riboflavin, B12 and iodine by roughly half in children — which is why UK and paediatric guidance is consistent that plant drinks given to children should be both unsweetened and fortified.

None of that rules out making your own. It means the nutrients need to come from somewhere you have actually thought about — a supplement, fortified foods, or keeping a carton for the children and making your own for your coffee.

The fibre question, honestly

Oats contain beta-glucan, a soluble fibre with one of the better-evidenced effects in nutrition: around 3 g a day is associated with lowering blood cholesterol, and that claim is authorised in EU and UK law rather than being marketing.

The catch is that oat milk is a poor delivery vehicle for it, homemade or otherwise. A barista carton carries 0.8 g of fibre per 100 ml, of which only part is beta-glucan; homemade carries less, because most of it stays in the pulp you strain out. Getting 3 g a day from oat milk would mean drinking several litres.

So do not make oat milk for the fibre. Eat porridge for the fibre — and use the pulp, which is where a good deal of it went. Stirred into porridge, flapjacks or banana bread, it is the cheapest health upgrade in this whole process, and most people bin it.

What we would actually tell you

Making your own oat milk is a good idea for reasons that are mostly not about health: it costs about a fifth as much, it tastes better fresh, and it removes a carton from your weekly shop.

The health story is narrower but real — substantially less sugar, no phosphate additive, no gums, and control over fat and salt. It is undermined entirely if you do not deal with the fortification gap, and it is oversold by anyone who tells you cartons are dangerous. They are not. They are a reasonably-designed processed food doing a specific job.

The setup that makes sense for most households is the boring one: make your own for everyday coffee, keep a fortified carton for the people and situations that need one, and get your calcium, iodine and B12 from a source you have chosen deliberately rather than from a drink you happened to stop buying.

If you want the practical side, start with why homemade oat milk goes slimy and which machine is worth it.

Sources

Nutrition figures for the carton are the manufacturer’s published UK values and were correct at the time of writing; check the pack, since formulations change.

Is homemade oat milk healthier? What the evidence actually says