Plant-based milk vs. dairy for health
A few weeks ago, we featured an article that looked at the different milk products available, and how they stand up in the environmental stakes. Today, we’re taking a different angle. Leah Dowling, a lecturer in dietetics at Swinburne University of Technology, explores the health pros and cons of milk and plant-based milk alternatives.
Spoilt for choice
A trip to the supermarket presents shoppers with an overwhelming number of milk choices. Far from just being the domain of the hipster, plant-based milk is going mainstream.
These alternatives may be suitable for people who are intolerant to dairy milk, or have ethical or other personal dietary preferences. They tend to be lower in saturated fats and energy than dairy milk. But they’re also lower in protein (except for soy) and calcium (unless it’s fortified). Some are also high in added sugars.
As to which milk is best, there’s no simple answer. Dairy milk tends to come out on top for nutrient quality, though soy is a good substitute from a nutrition perspective. And it should be noted these alternatives aren’t technically milks, as they’re not derived from mammals.
Nevertheless, the nutritional quality of the different plant-based milk alternatives varies considerably. So it’s important to take note of these when making your selection.
Milk provides us with important nutrients, including calcium, protein, vitamins B12, A and D, riboflavin (B2), zinc, phosphorus and iodine. The quantity and quality of cow’s milk proteins is high, with both whey and casein containing all nine essential amino acids. Milk plays an important role in bone health and is a particularly rich source of dietary calcium.
Research investigating the ability of the body to absorb and utilise calcium determined the best-absorbed calcium source is dairy milk and its derivatives.
Although dairy foods do contain some saturated fats, the fat in dairy doesn’t seem to be overly problematic for heart health. A large 2018 study featuring people from 21 countries found dairy consumption was associated with a lower risk of heart disease and death.
Although dairy milk has a high nutritional value, there’s no reason why people need to drink it if they choose not to. All of the nutrients in milk can be obtained elsewhere in the diet.
If you’re seeking a dairy-free alternative, then soy is a good choice. However, some people may be intolerant to soy. It’s made from ground soybeans or soy protein powder, water and vegetable oils. It’s also usually fortified with vitamins and minerals, including calcium.
A 2017 study found soy fared considerably better than other milk alternatives – including almond, rice and coconut varieties – in terms of nutritional profile.
Available in full-fat and low-fat, soy is a good source of plant protein, carbs and B vitamins. Most are also fortified with calcium, making them nutritionally comparable to dairy. The ability of the body to absorb and use the added calcium in soy milk is approaching that of dairy. One study indicated calcium from fortified soy milk was absorbed at 75 percent of the efficiency of calcium from dairy milk. However, there appears to be limited data on this.
Soy milk typically contains more protein than other plant-based milk alternatives. It also contains healthy unsaturated fats and fibre, and compounds called phytoestrogens. Phytoestrogens are natural plant compounds that imitate the body’s own natural oestrogen but to a lesser extent. There was initially some speculation based on earlier animal studies about potential adverse effects of phytoestrogens on the risk of breast cancer and hyperthyroidism. But studies conducted in humans don’t support this.
Conversely, there’s some evidence to suggest they may have a protective effect against some cancers. A study from 2019 found soy consumption is more beneficial than harmful. In a position statement on soy, phytoestrogens and cancer prevention, the Cancer Council of Australia supports the consumption of soy foods in the diet but doesn’t recommend high dose phytoestrogen supplementation, especially for women with existing breast cancer.
Nut milks such as almond consist mainly of ground nuts and water. Despite almonds being a good plant source of protein, almond drink is significantly lower in protein and calcium than dairy milk. Consumers who choose to drink almond milk need to ensure they get these essential nutrients elsewhere in their diet.
In a 2017 survey of widely available commercial almond milks, consumer group Choice found almond milk contained only two to 14 percent almonds, with water being the predominant ingredient. Almond milk tends to be low in energy and saturated fat. It contains some healthy unsaturated fats as well as vitamin E, manganese, zinc and potassium.
Almond milk often contains added sugars. Terms to keep an eye on include those indicating added sugars, such as organic rice syrup, agave syrup, organic evaporated cane juice, raw sugar or organic corn maltodextrin. It’s best to look for unsweetened varieties if you can.
Almond milk may be suitable for people who are intolerant to both dairy milk and soy. But it isn’t suitable for those with nut allergies.
If you’re using almond milk as an alternative to dairy milk and want similar nutritional benefits, look for one that’s fortified with calcium. Aim for as close to 115-120mg per 100ml (similar to dairy milk) as possible.
Oat milk is made by blending oats and water, then straining off the liquid. It’s a source of fibre, vitamin E, folate and riboflavin. It’s low in fat and is naturally sweet, containing double the carbs of cow’s milk, so it may not be suitable for people with diabetes. It tends to be low in both protein and calcium, so look for a fortified brand. It’s not suitable for people with a gluten intolerance, nor is it a nutritionally adequate substitute for young children.
Coconut milk is low in protein and carbohydrates, and high in saturated fat. Some brands have added sugars. Similar to nut drinks, it doesn’t naturally contain calcium and isn’t a suitable substitute for dairy milk nutritionally.
Rice milk is produced from milled rice and water. It’s naturally high in carbohydrates and sugars. It also has a high glycaemic index, which means that glucose enters the bloodstream quickly. This may mean it’s not suitable for people with diabetes. It’s also particularly low in protein and needs to be calcium fortified.
Rice is the least likely to trigger allergies of all of the milk alternatives. However, it’s not a suitable milk substitute, particularly for children, due to its low nutrient quality.
Ultimately, when deciding which plant-based milk to drink, you should choose fortified and preferably unsweetened varieties. Also, look for those with a calcium content as close to 115-120mg per 100ml (or 300mg per cup) as possible. This is similar to dairy milk.
Your choice should also take into account your individual nutrient requirements. This is especially important for children, teens, older adults and those on a restricted diet. Finally, factors such as flavour, taste, texture and mouthfeel are all important considerations.
Leah Dowling is a lecturer in dietetics in Swinburne University of Technology. This article originally appeared on The Conversation.