2. Classification of Plant-Based Drinks
Plant-based drinks can be classified according to the raw materials used, such as almonds, oats, soy, walnuts, peanuts, coconuts, cashews, rice, hemp, and flax (
Table 1). Plant-based drinks can be broadly classified into six types based on raw materials: cereals (oats and rice), legumes (soybeans and peas), pseudo-cereals (quinoa), seeds (peanuts, sesame, and sunflower), nuts (walnuts and almonds), and high-protein or fatty fruits (coconut). Beverages made from plant-derived ingredients and plant proteins are also referred to as plant-based drinks
[7]. Plant-based drinks provide supplemental proteins, calcium, and various other nutrients. They can be consumed in pure form or used as a companion for coffee and tea, and can serve as an ingredient in processed foods (baked products and plant-based ice cream).
Table 1.
Plant-based drink classification by raw material source.
18]. Methionine and cysteine are the limiting amino acids in pea and soy tissue proteins, whereas lysine is the limiting amino acid in flax proteins and other cereal proteins, including rice
[19]. Due to the limited presence of these amino acids, plant proteins are generally considered to provide a lower nutritional value than animal proteins. Additionally, the presence of plant-derived anti-nutritional factors, including phytic acid and saponins, results in the lower digestibility of plant proteins relative to milk protein. Overall, the biological value (BV) and digestible indispensable amino acid scores (DIAASs) of plant proteins are slightly lower than those of milk proteins. For example, BV scores for milk protein and casein are 104 and 80, respectively, whereas BV scores for soy, pea, and flaxseed proteins are 74, 65, and 77.4, respectively. DLAASs for milk protein and casein are 115 and 111, respectively, whereas DLAASs for soy and pea proteins are 89 and 80, respectively
[16][19][16,19]. Besides protein, other compositions of plant-based drinks can be seen in
Table 2.
Table 2.
General composition of different plant-based drinks.
3.3. Fats and Fat-Soluble Ingredients
Plant-based drinks primarily contain unsaturated fatty acids with generally low levels of saturated fatty acids and no cholesterol. This composition is beneficial for lowering low-density lipoprotein and cholesterol levels, thus providing positive effects to individuals addressing high blood cholesterol and cardiovascular diseases
[36]. Polyunsaturated fatty acids (PUFAs), a subgroup of dietary fats encompassing omega-3 and omega-6 fatty acids, confer a spectrum of health benefits when judiciously incorporated into the diet. These benefits are underpinned by intricate biochemical mechanisms. Omega-3 PUFAs, notably found in fatty fish and flaxseeds, substantiate reduced risks of cardiovascular disease through the mitigation of triglyceride levels, blood pressure regulation, and anti-inflammatory actions. Furthermore, omega-3 PUFAs exhibit anti-arrhythmic properties, modulating heart rhythm and averting arrhythmias. In terms of cognitive well-being, these PUFAs, particularly docosahexaenoic acid (DHA), assume a pivotal role in brain development and function, enhancing cognitive faculties and conferring protection against neurodegenerative conditions, such as Alzheimer’s disease. Additionally, mood regulation is influenced by omega-3 PUFAs, which may ameliorate symptoms of depression and anxiety. Their robust anti-inflammatory attributes extend to the management of chronic inflammation, impacting the pathogenesis of prevalent ailments including cardiovascular disorders, arthritis, and certain cancers. Beyond these, omega-3 PUFAs underpin various other health benefits, including skin barrier fortification, immune system augmentation, eye health preservation, potential cancer risk reduction, appetite regulation for weight management, and vital contributions to pregnancy and child development. To optimize these benefits, maintaining an appropriate balance between omega-3 and omega-6 intake is pivotal, as excessive omega-6 and insufficient omega-3 consumption can contribute to inflammatory states and health complications. Consequently, a balanced diet integrating sources of both omega-3 and omega-6 PUFAs is advocated for comprehensive health promotion. Overall, higher proportions of PUFAs, especially n-3 PUFA, other bioactive essential fatty acids, and fat-soluble bioactive components, contribute to the prominent health benefits of plant-based drinks (
Table 3).
Table 3.
Main fatty acid components of plant-based drinks.
Table 5.
Main vitamin components of plant-based drinks.
3.4. Vitamins and Minerals
Most plant-based drinks are rich in minerals including calcium, magnesium, selenium, potassium, zinc, phosphorus, copper, and manganese (
Table 4). For example, the respective almond and soybean calcium contents are approximately 269 and 277 mg/100 g, whereas the respective magnesium contents are approximately 270 and 280 mg/100 g. The respective potassium contents are approximately 733 and 1797 mg/100 g. The endogenous calcium content of plant-based drinks varies widely among products, but when fortified with external sources of calcium, the calcium content in plant-based drinks is typically higher than that in cow’s milk
[43]. In general, the absorption rate of calcium carbonate used for calcium fortification of plant-based drinks is high, although calcium carbonate is prone to precipitation, which reduces calcium bioavailability in plant-based drinks
[44][45][44,45]. Cow’s milk is considered an excellent source of vitamins; however, it has a low vitamin D content and usually requires external supplementation for fortification (
Table 5). Plant-based drinks also tend to have low vitamin D content. Therefore, commercially available plant-based drink products are often fortified with vitamin D. Soy drinks and almond drinks also have an advantage over cow’s milk in vitamin E content, with levels reaching approximately 4.0 and 3.84 mg/100 mL, respectively. Coconut, almond, and cashew drinks have vitamin A contents exceeding 60 μg/100 mL, approximately twice the amount found in cow’s milk
[46]. Overall, plant-based drinks have an advantage over cow’s milk in terms of fat-soluble vitamin content, whereas water-soluble vitamins may require fortification.
Table 4.
Main mineral components of plant-based drinks.
3. Plant-Based Drink Nutrients
3.1. Protein
In the absence of added exogenous protein, soy-based plant drink has the highest protein content, similar to that of cow milk. Soy-based plant drinks are generally considered to be a complete protein source for adults, containing all essential amino acids. Other plant-based drinks have lower protein contents, with rice-based plant drinks having the lowest protein content
[16][17][16,17]. Compared to milk protein, plant-based drinks may exhibit slight quantitative deficiencies in some essential amino acids, such as methionine and lysine
[
3.2. Dietary Fiber
Dietary fiber refers to the non-digestible carbohydrates present in plant-based foods
[27]. It primarily exists in plant cell walls and includes cellulose, hemicellulose, and soluble fibers. Dietary fibers remain structurally intact as they pass through the digestive tract because they are not broken down by digestive enzymes in the human body
[28]. Dietary fibers offer various health benefits, including promoting gastrointestinal health, preventing constipation, controlling blood sugar and cholesterol levels, providing a feeling of fullness, and regulating body weight. Common sources of dietary fiber include whole grains, vegetables, fruits, legumes, nuts, and seeds. It is recommended that adults consume 25–30 g of dietary fiber per day to maintain good health
[29][30][31][32][29,30,31,32]. In plant-based drinks, various soluble or insoluble dietary fibers present in the cell walls of seeds, cereals, or fruit-based ingredients, such as flaxseed gum, almond polysaccharides, and soy polysaccharides, exhibit potential prebiotic characteristics that are beneficial to human health. This prebiotic function is not inherent to dairy milk. Prebiotics are compounds resistant to digestion in the small intestine, and select dietary fibers, such as inulin, oligofructose, and fructooligosaccharides (FOSs), fall into this category. They play a prominent role in regulating the gut microbiota and promoting gut ecosystem health
[33][34][33,34]. This microbial fermentation process generates short-chain fatty acids (SCFAs), notably butyrate, acetate, and propionate, which confer various health advantages, including trophic effects on colonic epithelial cells and the mitigation of inflammatory responses. Additionally, prebiotic fibers foster gut microbiome diversity by providing diverse nutritional substrates for a spectrum of bacterial strains. A balanced and diverse gut microbiome is associated with improved gastrointestinal function, enhanced immune responses, and potential implications for neurological health. More specifically, beta-glucan in oat drinks increases satiety and lowers blood glucose and cholesterol levels
[7]. Flaxseed drink contains flaxseed gum, which improves the gut microbiota, controls weight, enhances satiety, and protects gut and cardiovascular health. Soy drinks containing fiber can lower plasma cholesterol in animals or humans without affecting the absorption of essential mineral elements, including zinc and copper. It also helps maintain gut health and controls blood sugar and lipid levels
[35].
3.5. Bioactive Molecules
Plant-based drinks generally contain beneficial bioactive molecules, including flavonoids, phenolic acids, lignans, and phytosterols (
Table 6)
[47]. Plant polyphenols exhibit excellent antioxidant properties and provide significant health benefits, including anticancer effects, protection against radiation damage, antimicrobial activity against pathogenic bacteria, lipid-lowering effects, and the prevention of cardiovascular diseases. Resveratrol in peanut drinks reportedly possesses antioxidant, antibacterial, hepatoprotective, cardiovascular, radioprotective, and anti-HIV activities
[48]. Sesamol in sesame drinks has been reported to inhibit obesity and insulin resistance in mice fed a high-fat, high-fructose diet. It reduces hepatic fat synthesis, inhibits lipid accumulation and inflammatory responses in white adipose tissue, and decreases adipocyte size while promoting the conversion of white adipose tissue to brown adipose tissue by improving mitochondrial lipid metabolism
[49]. Lignans, such as enterolignans, are natural plant estrogens found in high amounts in flaxseed drinks. They can control the production of three types of estrogen, inhibit ovarian estrogen production, reduce the risk of breast cancer, and exhibit significant anti-colorectal cancer effects. Their antioxidant function primarily centers on the neutralization of free radicals, highly reactive molecules capable of inducing cellular damage, including DNA, protein, and lipid harm, potentially culminating in cancer and other chronic maladies. The mechanistic underpinnings of lignan-mediated anti-cancer effects encompass several facets: free radical scavenging via electron donation, the modulation of inflammatory processes, participation in estrogen metabolism pathways (particularly enterolignans), interference with key cellular signaling pathways implicated in tumorigenesis, the induction of apoptosis, and the regulation of angiogenesis. Moreover, lignans may enhance detoxification processes via the upregulation of detoxifying enzymes. Consequently, a growing body of research suggests that lignans may be associated with a diminished risk of specific cancer types, particularly hormone-related malignancies like breast, prostate, and ovarian cancers.
[50]. The role of flavonoids within plant-based drinks hinges upon their natural occurrence in constituent ingredients or their introduction during processing. Certain plant-based drink varieties, such as almond and soy drinks, may contain inherent flavonoids derived from their foundational ingredients, endowing these beverages with antioxidant capabilities. These flavonoids possess the capacity to mitigate oxidative stress and confer potential health benefits. However, it is important to note that flavonoid enrichment is not a prevailing practice in commercially available fortified plant-based drinks, which predominantly focus on the fortification of vitamins and minerals to replicate the nutritional profile of dairy milk. Therefore, individuals with specific health risks, such as those at a high risk of cardiovascular diseases, may experience enhanced benefits from consuming plant-based drinks.
Table 6.
Total phenolic compounds and phytosterol compositions of plant-based drinks.