Milk vs. Plant-Based Drinks – How Do They Compare?
Today, there is a growing trend toward drinking plant-based beverages.
In a recent survey, almost half of the people cited ‘nutritional value’ as the primary reason for making the switch, particularly amongst parents feeding their children.(1)
Are plant-based beverages really more nutritious than milk? Are they even equally as nutritious?
The most common plant-based beverages available include almond, rice, oat, soy and coconut (amongst a few others).
Let’s review the available evidence on the macro- and micronutrient status for milk and plant-based beverages.
#1 Macronutrients – Protein, Carbs & Fats
Protein is an essential building block for life; all your cells, enzymes, muscles and hormones need protein.
With regards to protein, there are two important factors to consider; protein total and protein quality.
Protein total is the amount of protein you consume in a day and milk provides 8-9g of high quality protein per cup. Comparably, plant-based beverages are not a good source of protein, providing only 1-2g per cup, with the exception of soy which nets 7-8g (see Table 1 below).
The recommended dietary allowance (RDA) for protein is set at 0.8g/kg/day, however what often goes unnoticed is that the RDA assumes you’re eating 50% of your protein intake from some animal sources (e.g. egg and dairy).(2)
This is an important consideration because vegetarians may be consuming as little as 20% of their protein from eggs and dairy (and vegans obviously zero percent).(3)
Why is this potentially a problem?
Protein quality.
Vegetable proteins generally have a lower ‘digestibility’ and inferior amino acid profile (building blocks of proteins) compared to animal-based proteins consumed by omnivores.
The essential amino acid leucine, found in higher concentrations in milk and animal-based proteins, is crucial for triggering protein synthesis in the body to rebuild your cells, muscles, hormones, and body.(4,5)
Does this mean vegetarians cannot achieve the desired leucine intake?
Of course not, but it does mean vegetarians need to consume a higher amount of protein to offset this fact.
Currently, the most advanced method for assessing protein quality is called the Digestible Indispensable Amino Acid Score (DIAAS), providing a more ‘real-world’ ranking system of how well your body can actually use the proteins you eat.
Here is how the DIAAS scoring system work;
- Greater than 100 = ‘excellent’ quality protein
- 75-99 = ‘good’ quality protein
- Less than 75 = ‘poor’ quality protein
A DIAAS score of 100 or more, such as that found in milk, reflects the fact that all the amino acids required for human health are present in the meal.(6,7,8)
Generally, plant proteins and cereal grains have DIAAS values that are less than 75.(6-11)
The DIAAS scores for common protein sources are listed below;
· Milk – 122
· Meat - 99
· Soy – 90
· Oats – 75
· Peas – 64
· Rice - 60
· Wheat - 54
On a day to day basis, what does mean for you?
For example, you would have to consume more than double the amount of pea protein (DIAAS of 64) compared to milk (DIAAS of 122) to meet the same amino acid requirements.(12)
It’s a nuance often missed by plant-based eaters and the major reason why it’s important for vegetarians to combine protein sources at meals.
[It’s important to note much of the research on protein quality is performed to combat undernutrition and protein malnutrition around the world which affects over 800 million people and 1 in 4 children under the age of five].(13)
With respect to carbohydrates, plant-based beverages like almond and coconut are typically lower in carbohydrates, while oat and rice contain much more at 16.5g and 26.0g per cup, respectively. This is an important consideration for anyone following a low-carb or keto diet.
The fat content of plant-based beverages is also typically lower than 2% and 3.25% milk, yet comparable to 1% milk. Skim milk has the lowest fat content.
Table 1 – The macronutrient breakdown of milk and common non-dairy drinks.
To Sum Up
Plant-based beverages are significantly lower in total protein content and have a markedly inferior protein quality compared to milk.
If you’re looking to add a splash of a plant-based beverage to your coffee or tea, it’s not a problem; but if you’re consuming plant-based beverages to upgrade your protein intake, they’re a very poor choice.
#2 Micronutrients
The general public appears to believe, as mentioned above, that plant-based beverages are just as good (if not superior) to milk with respect to nutrient-density.
While the macronutrient breakdown of plant-based beverages (discussed above) is fairly consistent from drink to drink, the micronutrient content of plant-based beverages vary dramatically from brand to brand and is scarcely available in the research.(14)
How do milk and plant-based beverages stack up when it comes to micronutrient status?
Let’s review.
Calcium
Calcium is essential for human health. It supports healthy bones, teeth, muscle contraction, nervous system function, amongst many other vital physiological function.(15)
Cow’s milk contains 300mg of calcium per cup and most plant-based beverages are fortified with similar concentrations of calcium. (See Table 2 below) However, it’s important to note that the addition of fortified calcium doesn’t guarantee nutritional equivalence.
The bioavailability of calcium among fortified plant-based beverages actually varies dramatically from one to another.
For example, some brands use a form of calcium called tricalcium phosphate, which is poorly absorbed, rather than calcium carbonate. The fortified calcium in plant-based beverages can also form a residue at the bottom of cartoons, further reducing bioavailability.
In short, fortified calcium in plant-based beverages is not equivalent to that found in milk.(16)
In young children, this is especially important.
A glass of milk provides half of the RDA of calcium for young children, a crucial time in growth and development, and the lactose and casein in milk actually enhances calcium absorption.(17,18)
Magnesium
Magnesium is involved in hundreds of diverse biochemical reactions in the body that support health and vitality. Milk provides approximately 25mg of magnesium per cup, whereas rice and soy provide a little more at 40mg per cup (and almond milk a little less).
Once again, bioavailability is the concern; milk and plant-based beverages are not considered equal in the research.
Why?
For example, the higher phytate content in soy impairs both calcium and magnesium absorption unless manufacturers supplement plant-based beverages with phosphorus and calcium, or phosphorus, calcium and the amino acid methionine.(19)
It’s not clear on plant-based beverage labels, or in the research, if this is done.
Zinc
Zinc is another key mineral fulfilling essential roles in the body. Zinc is essential for DNA repair, supports cellular health and protein metabolism, is vital for immune system function, thyroid and testosterone health, amongst many other crucial roles.(18)
Milk is a good zinc source, providing 1mg per cup, whereas plant-based beverages range from 0-0.25mg. Once again, the zinc from milk is more bioavailable than plant-based sources.(18)
Table 2 – Micronutrient Profiles of Milk and Plant-Based Beverages
Vitamin A
In nature, vitamin A is actually a group of compounds called retinoids found in animal foods, whereas plants contain carotenoids, most notably beta-carotene which is a precursor to vitamin A.
Beta-carotene from the vegetables we eat must therefore must be converted into vitamin A – via series of biochemical steps.
Milk is fortified with vitamin A, palmitate or retinol palmitate, as these are the most stables forms of vitamin A and emulsify well in milk. Plant-based beverages are also fortified with vitamin A, although the form and quantity varies by brand.
Vitamin D
Cow’s milk, like plant-based beverages, is also fortified with vitamin D. This is particularly important in early childhood, where deficiency can lead to bone and skeletal disorders.
A recent study in a leading pediatric medical journal warned replacing cow’s milk with plant-based beverages could possibly place children at unnecessary risk of complications from low dietary vitamin D.(20)
In Canada and other countries, pediatricians are seeing a resurgence in the number of cases of severe rickets in children who did not drink cow’s milk.(21)
A recent survey of Canadian pediatricians uncovered 149 cases of children with severe vitamin D deficiency in the past year, which included 48 cases of rickets, and tragically two deaths.(22)
To Sum Up
While plant-based beverages contain significant levels of specific micronutrients, they lack the full spectrum found in milk and micronutrient bioavailability remains a concern.
For this reason, plant-based beverages are actually not listed as part of Canada’s Food Guide (with the exception of soy).(23)
This is even more important to remember for kids, as the substitution of cow’s milk for plant-based beverages has been repeatedly shown to lead to nutrient deficiencies.(20,24)
The Bottomline – Milk vs. Plant-Based Drinks
The popular opinion that plant-based beverages are healthier than milk is not supported by scientific evidence.
If you struggle with a true milk allergy, plant-based beverages can be helpful to add in your coffee or tea as an alternative.
However, from a nutrition standpoint the research clearly shows milk has a superior protein quality and micronutrient profile compared to plant-based beverages.
If you’re a parent, consider the following quote from a leading European pediatric journal…
“Non-dairy beverages vary in their nutritional profiles. These should not be considered nutritional substitutes for milk until the nutrient quality and bioavailability are established.”(22)
Nutrition is deeply complex, the diet you follow doesn’t have to be.
Milk is an ‘easy win’ to support better health, body composition, longevity in adults and growth and maturation for kids.
Dr. Marc Bubbs ND, MSc, CISSN, CSCS
p.s. What role do cows play in our health and the health of the planet? Listen to my recent interview with Diana Rodgers, RD, MS about her new book (and film) Sacred Cow - The Case for (Better) Meat.
References
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