What Affects the Nutritional Quality of Plant-Based Milk Substitutes?

Patient Presentation
A 12-month-old female came to clinic with her mother for her health supervision visit. The infant was breastfeeding and had a history of cow’s milk protein and soy allergies where the patient had bloody stools or hives. The family was vegetarian but ate some dairy products and eggs. She asked about using a pea-based milk substitute to wean the infant. The family had tried eggs and peanut products without any problems for the infant. They also had tried some yogurt and felt her stools were much looser but there was no obvious blood in them. The infant ate age-appropriate complimentary foods without difficulty. The past medical history was otherwise negative.

The pertinent physical exam showed a healthy female with weight in the 25-50% and height and head circumference in the 50-75%.
Her physical examination was normal.

The diagnosis of a healthy female with food allergy or sensitivities was made.
The pediatrician knew that there could be problems with plant-based milk substitutes for young children including protein and other nutrient insufficiencies depending on the product used.
“Let me do a little research and talk with the hospital dietician who works in our gastroenterology clinic. I’ll get back to you in a few days but in the meantime, just continue the formula,” he answered.

People today may be eating more plant-based products because of:

  • Allergen avoidance – lactose or cow’s milk allergy, 14% of people with cow’s milk allergy will also have soy allergy.
  • Cultural importance
  • Contamination avoidance e.g. growth hormone or antibiotic residues in cow’s milk production
  • Specific diseases, e.g. cholesterol/lipid issues
  • Environmental impact
  • Ethical or religious considerations
  • Improved nutrition

With population growth “[t]he demand for food is expected to grow by 70% until 2050….While the expected protein consumption is believed to grow by 80%.” Protein sources are also expected to come from more resource intense foods.

Plant-based milk substitutes (PBMS) look like cow’s milk but are water-based extracts of legumes, oil seeds and nuts, cereal or pseudocereals. Soy milk and other soy products are the most common globally.

Common commercial plants utilized include:

  • Soy
  • Almond
  • Coconut
  • Hemp
  • Kamut
  • Oat
  • Maize
  • Millet
  • Peanut
  • Quinoa
  • Rice
  • Rye
  • Sesame
  • Sorghum
  • Tiger-nut (actually a tuber) – used to make Horchata
  • Wheat

Some plant-based drink examples include:

  • Amazake – rice, from Japan
  • Atole, maize, from Mexico
  • Boza – wheat, rye, millet, maize, common in south eastern Europe
  • Bushera – sorghum or millet, from Uganda
  • Chicha – grains and fruits, common in the Andes mountains
  • Horchata or tiger-nut milk, from Spain
  • Sikhye – rice, malt and sugar from South Korea
  • Soy milk – soy, from Asia especially China

The basic PBMS production process involves:

  • Taking the plant, adding water and grinding into a slurry- the plant can have water added first then is wet-milled, or is dry-milled then water is added to the resulting flour
  • Separating the solid wastes by filtration, decanting, centrifugation, etc.
  • Product formulation including other treatments such as fermenting or adding oil, flavoring, sugars, stabilizers and nutritional fortifiers
  • Homogenization to keep the product in the water suspension otherwise the particles can separate out as these are emulsions or colloidal suspensions
  • Pasteurization or ultra high temperature treatment to prevent microbial contamination
  • Packaging

Product formulations are affected by many things including temperature, pH, treatment duration, and when in the process the treatment is done. These make various nutrients more or less available (especially protein and fat) and with different qualities (i.e. textures, tastes, that make the end product more desirable to consume and nutritionally preferable). Fermentation, using bacteria, fungi or yeasts, is often used to improve nutrition, taste, and shelf life.

Additions to the basic product are exceptionally diverse because of the diverse products being made. Stabilizers prevent product degradation and nutritional supplements may be needed because naturally occurring water-soluble vitamins and other nutrients were destroyed or lost in the processing. Even different calcium types, added to fortify the product and to stabilize it, and make the calcium partially or wholy bioavailable. Calcium is less bioavailable if calcium triphosphate is used but is 100% bioavailable if calcium carbonate is used. Additions can also include animal ingredients.

Consumers often expect PBMS or other plant products to taste like cow’s milk or animal products when they are not. Some consumers complain of a chalky or pasty feel or of a beany taste. “[A] good approach…would be to appreciate the taste of the plant ingredients.” Producers are trying to make products that are nutritious, tasty and affordable for consumers.

High quality data is limited to determine the impact of protein products on the environment but they may have an improved impact utilizing less land but the issue is complex. For example, almonds are a good source of PBMS. Almonds are grown mainly in California (80%) and they require a great deal of amount of water which is limited. They also do not wind-pollinate well and therefore require bees for pollination and unfortunately the bee populations are also dwindling. Environmental contaminants can also occur in plant-based products and not solely in animal based products.

Learning Point
“In reality the nutritional properties [of plant products] vary greatly, as they depend strongly on the raw material, processing, fortification, and the presence of other ingredients such as sweeteners and oil.”

In general however, plant-based products have:

  • Lower protein and the protein is of lower quality – the protein may be of lower quality because of limiting amino acids (legumes = methionine, cereals = lysine) however again it depends on the actual product.
  • Lower cholesterol and improved lipid profile
  • Calories are about the same as skin milk
  • May have lower calcium, iodine, iron, phosphorus, vitamin B12, riboflavin, zinc, etc.
  • More or less allergens

PBMS are often lower in protein and young children are potentially at risk for protein malnutrition if PBMS are used without an understanding of the differences between animal milk and PBMS. Not only protein may be insufficient for infants but other vitamins and minerals may be insufficient. Some PBMS do have higher protein levels such as peanut or cowpea products, but again it depends on the actual product.

Questions for Further Discussion
1. What types of foods should vegetarians eat to maintain their nutrition? A review can be found here
2. How much protein does someone need to eat? A review can be found here
3. What are indications for consultation with a dietician?

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for these topics: Vegetarian Diet and Nutrition.

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

Jeske S, Zannini E, Arendt EK. Past, present and future: The strength of plant-based dairy substitutes based on gluten-free raw materials. Food Res Int Ott Ont. 2018;110:42-51.

Makinen OE, Wanhalinna V, Zannini E, Arendt EK. Foods for Special Dietary Needs: Non-dairy Plant-based Milk Substitutes and Fermented Dairy-type Products. Crit Rev Food Sci Nutr. 2016;56(3):339-349.

Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa