Among plant-based options, soy milk remains the closest nutritional match to cow’s milk.

“Regular soy milk is the most comparable to cow’s milk when it comes to energy, protein and fat content; if it’s fortified with calcium, it’s even closer,” says registered dietitian Lily Henderson.

Protein is where many alternatives fall short. Almond, oat, coconut and rice milks are typically much lower in protein, which affects satiety and overall intake, particularly for children, teenagers and older adults.

Oat milk’s sugar surprise

Oat milk often wears a health halo, but it behaves differently from other alternatives.

“Oat milk is particularly interesting because its production process breaks down oat starch into simpler sugars like maltose,” says Sekula. “This means oat milk typically has a higher carbohydrate and sugar content than other plant-based milks.”

That sugar isn’t added in the traditional sense, but it still counts metabolically. For people managing blood sugar levels, or those using oat milk several times a day in coffee and cereal, this distinction is easy to miss.

Oat milk does offer one advantage: it contains beta-glucan, a soluble fibre not found in most other milk alternatives. However, it is generally low in protein and many oat milks are not suitable for people who must follow a strict gluten-free diet, unless they are specifically certified gluten-free.

Almond milk is lighter than many realise

Almond milk’s popularity rests largely on perception. Commercial versions can contain as little as 2% almonds, which explains their low energy and protein content.

Some newer “high-protein” almond milks boost numbers by adding soy protein, something many shoppers may not realise.

“If you’re using almond milk regularly, you need to make sure protein and calcium are coming from elsewhere in the diet,” Henderson says.

Coconut milk’s trade-offs

Coconut milk tends to be lower in protein than other plant-based milks and higher in saturated fat. It is also commonly lacking calcium.

If it’s used occasionally in cooking, that’s not a concern, but as a daily milk replacement it can leave nutritional gaps unless fortified.

Rice milk and allergy-friendly options

Rice milk plays an important role for people with multiple food allergies, but nutritionally it is low in protein, relatively high in carbohydrates, and its overall energy content is mostly from starch‑derived sugars rather than protein or fat.

As with several other alternatives, it works best when complemented with other protein-rich foods. Emerging options such as pea and hemp milks are appearing more often, but Henderson says the same rules apply.

“As with all other plant-based milks, it’s still important to check the label carefully for protein, calcium and other added nutrients.”

Calcium is not optional

Both dietitians stress that calcium fortification is essential, not a bonus.

“Choosing a calcium-fortified plant-based milk is essential because dairy products are a major dietary source of calcium,” says Sekula.

The benchmark to look for is clear. “Look for a plant-based milk that provides at least 120mg of calcium per 100ml, listed in the Nutrition Information Panel,” she says.

Added vitamin D is also useful, as it supports calcium absorption and many New Zealanders don’t get enough year-round.

Should we worry about oils and additives?

Many plant-based milks include small amounts of vegetable oils, such as rapeseed or sunflower oil, to improve texture. Barista-style milks often contain additional thickeners to help foam hold.

Despite online concern, Henderson says the evidence doesn’t warrant alarm.

“The vegetable oils are present in small amounts, and there is no strong evidence from systematic reviews or meta-analysis to suggest that these ingredients are harmful to our health.”

Because of how these products are made, added ingredients are difficult to avoid entirely. For those who prefer less processing, shorter ingredient lists can be a useful guide.

Homemade milks fall short

Homemade nut and seed milks may feel cleaner, but nutritionally they don’t compare.

“Homemade plant-based milks are not fortified, so they do not provide enough calcium to replace cow’s milk,” says Sekula. “For this reason, they are not recommended as a substitute for cow’s milk and should not be used for children.”

What parents need to know

One detail many families miss is labelling around protein content.

“Plant-based milks that contain less protein than cow’s milk are required to carry a label advising that they are not suitable as a complete milk replacement for children under 5 years old,” Henderson says.

For children avoiding dairy, both dietitians recommend working with a health professional to ensure energy and protein needs are met during growth and development.

Milk alternatives can absolutely have a place in a healthy diet, but they’re not interchangeable. Choosing a calcium-fortified option with adequate protein, understanding how different milks are made, and matching the product to how it’s actually used will do far more than assuming plant-based automatically means healthier.

Five plant-based milks that stack up nutritionally

Based on protein content, calcium fortification and overall nutritional balance, dietitians say these options come closest to doing the job of milk rather than just tasting like it.

Vitasoy Soy Milk Calci Plus Regular

Provides 3.2g protein and 160mg calcium per 100ml, and is fortified with vitamins B12 and D. A strong all-round option for people using plant-based milk daily.

Vitasoy Soy Milk Protein Plus

Higher protein at 4.2g per 100ml, with low sugar and 120mg calcium. Noted for its relatively simple ingredients list.

Sanitarium So Good Regular Soy Milk

Similar protein and calcium levels to cow’s milk, with added vitamins B12 and D, though with a longer ingredients list than some alternatives.

So Good Almond Milk High Protein

Enriched with soy protein, delivering 4.1g protein and 120mg calcium per 100ml. A better option for those who prefer almond milk but want more nutritional substance.

Macro Organic Oat Milk Unsweetened

Higher protein than most oat milks at 1.5g per 100ml, with 120mg calcium and no vegetable oil. Not fortified with additional vitamins, but notable for a short ingredients list.

Five options dietitians suggest minimising

These products fall short on protein, calcium or both, and are less suitable as regular milk replacements. They are options dietitians suggest minimising as everyday milk replacements (especially for children or people relying on them as a main protein and calcium source).

Macro Organic Almond Milk

Very low in protein at 0.4g per 100ml and provides only 33mg calcium, well below recommended levels.

Sanitarium So Good Almond Milk Vanilla

Low protein and added sugar, with sugar listed as the second ingredient, despite calcium fortification.

Real Foods Organic Oat Barista

Low protein and provides slightly under the recommended calcium benchmark at 100mg per 100ml.

Sanitarium So Good Coconut Milk Unsweetened

Extremely low in protein and calcium, making it a poor nutritional substitute if used regularly.

Pure Harvest Coconut Milk Coco Quench

A coconut and rice blend that is low in protein and not fortified with calcium or other key nutrients.

Herald contributor Nikki Birrell has worked in food and travel publishing for nearly 20 years. From managing your kitchen to cutting costs, she’s shared some helpful advice recently, including how to prep your barbecue for summer grilling, gourmet hacks for elevating budget ingredients and what toppings to choose for different crackers.