Dairy products are crucial nutrient sources globally, particularly in Western and some Asian countries, providing significant amounts of calcium, fat, and protein. However, milk consumption is declining in the West, partially replaced by plant-based beverages (PBBs). These PBBs are often marketed as healthy alternatives, but studies indicate they may be of lower nutritional quality. The term "milk" is often misused in PBB marketing, leading to consumer misguidance. The rise of PBBs is driven by lactose intolerance, milk allergies, veganism, animal welfare concerns, and perceived environmental benefits. Nutritional content in PBBs varies significantly based on plant source, fortification, and processing. Previous research suggests PBBs are often deficient in minerals, especially iodine, a critical element for thyroid hormone synthesis and neurological development. To address micronutrient deficiencies, many PBBs are fortified with minerals and vitamins, but declared nutrient content doesn't always match actual levels. This study aimed to quantify the composition (amino acids, fatty acids, minerals) of various PBBs and animal milks, and to comparatively analyze which PBB types approximate the nutritional profile of animal milk.

Existing literature highlights the importance of dairy in global nutrition, particularly its contribution to calcium, fat, and protein intake. Studies have shown a decline in milk consumption in Europe and the US, with a corresponding increase in PBB consumption. However, the nutritional profile of PBBs is often considered inferior to that of animal milk, particularly regarding mineral content and protein quality. The misuse of the term "milk" in PBB marketing is a concern, and studies comparing the nutritional value of PBBs to cow's milk have yielded varying results depending on factors such as fortification and processing methods. There's also discussion around the bioavailability of nutrients in PBBs, influenced by the presence of antinutrients. Methods for evaluating protein quality, such as PDCAAS and DIAAS, have been employed to compare protein sources, highlighting the superior quality of animal milk compared to most plant-based alternatives. Previous research is often limited to declared nutritional content rather than actual compositional analysis, which has been shown to be inaccurate.

Sixty PBB samples (twelve each of rice, oat, soy, almond, and coconut, with some removed due to incomplete data), eight UHT whole cow milk products, and eight UHT whole goat milk products were purchased from the Vicenza province in Northern Italy between February and March 2022. Only unfortified products were selected. Samples were analyzed for dry matter (%), gross composition (%), fatty acid profile (g/100 g), amino acid (mg/100 g beverage), mineral (mg/kg beverage), and iodine (µg/kg beverage) content in certified laboratories. Gross composition analysis included dry matter determination (freeze-drying), ash content (muffle oven at 550°C), crude protein (Kjeldahl method), and crude lipid content (Soxhlet extraction). Fructose, glucose, and lactose were quantified using HPLC. Amino acid analysis involved hydrolysis (different methods based on amino acid type), pre-column derivatization, and HPLC separation. Fatty acid analysis involved extraction with hexane:isopropanol, esterification, and GC analysis. Mineral and iodine content were determined via ICP-OES and ICP-MS after microwave acid digestion. Data analysis using R software included the Mann-Whitney U test for median comparisons, calculation of coefficient of variation (CV), principal component analysis (PCA), and linear discriminant analysis (LDA) to assess variability and discriminatory power of composition traits.

Soy-based beverages had the highest protein content (3.47%), followed by cow (3.42%) and goat milk (3.25%). Animal milks had higher levels of all essential amino acids except phenylalanine compared to soy PBBs. PBB groups differed significantly in individual amino acid content. Milk protein content and amino acid profiles were less variable than in PBBs, indicating inconsistent PBB production. DIAAS and PDCAAS scores showed that cow's milk had superior protein quality compared to the PBBs, with soy being the exception. Cow and goat milk had significantly higher lipid content (3.55% and 3.72%, respectively) than PBBs, with the lowest lipid content found in oat-based beverages (0.37%). Animal milk had a much higher proportion of saturated fatty acids (SFA) compared to PBBs (except coconut). PBBs had significantly higher unsaturated fatty acids (USFA), particularly polyunsaturated fatty acids (PUFA). Rice-based beverages had the highest carbohydrate content, while only cow and goat milk contained lactose. Many PBBs contained added sugar and salt, which may negate some of the perceived health benefits. Iodine was only detected in cow and goat milk. All minerals were generally higher in animal milk except magnesium. Soy PBBs had the highest mineral content among the PBBs. PCA and LDA analyses revealed distinct clustering of animal milk and PBBs, with soy PBBs differing most from other PBBs. Saturated fatty acid groups, C18:1n9, C16:0, and glutamic acid were identified as key discriminatory traits between milk and PBBs.

The findings demonstrate significant nutritional differences between animal milk and PBBs, except for soy-based beverages which showed comparable protein levels. However, even soy PBBs were inferior in iodine, calcium, and phosphorus content and differed in their fatty acid profiles. The lower bioavailability of nutrients in some PBBs due to antinutrients raises concerns about nutritional adequacy, particularly for vulnerable populations. The high variability in the composition of PBBs indicates a lack of standardization in manufacturing processes, making informed consumer choices challenging. The presence of added sugars and salts in many PBBs may negate any potential health benefits related to reduced saturated fats. Future research should focus on improving the nutrient density and bioavailability of PBBs while minimizing the environmental impact of their production.

This study highlights the significant nutritional discrepancies between animal milk and most plant-based beverages. While soy-based beverages show promise as a protein source, they lack the complete nutrient profile of animal milk. The low mineral content, high carbohydrate levels, and presence of antinutrients in many PBBs necessitate careful consideration, especially for vulnerable populations. Further research is needed to optimize the nutritional profile of PBBs while maintaining their sustainability.

The study was limited to a specific geographical region, and the results may not be generalizable to all markets. The number of samples per brand was relatively small, although sufficient for the statistical analysis. Not all fatty acids were individually identified and quantified due to limitations in the analytical techniques. Some PBBs contained additives that might influence the nutritional value but that were difficult to evaluate completely. Further research with a larger sample size and a broader range of brands and geographical locations is recommended.