Plant-Based Milks Show Stronger Antioxidant Balance Than Cow Milk, Study Finds

A comparative laboratory analysis of dairy and plant-based milks sold in the Turkish market has found that cow milk leads decisively on protein content, while several plant-based alternatives display higher catalase activity and markedly lower oxidative stress indices. The findings are reported in Frontiers in Nutrition, in the journal's food chemistry section. The research team analyzed pasteurized and UHT cow milk together with commercially available soy, almond, hazelnut, oat, and coconut milks, profiling each beverage for basic composition, antioxidant capacity, and markers of oxidative balance.

The researchers measured acidity, protein, fat, and ash contents as the physicochemical backbone of the comparison. Oxidative balance was evaluated using total oxidant status (TOS) and the oxidative stress index (OSI), which relates oxidant load to antioxidant capacity. Cow milk had the highest protein content of all products tested, followed by soy milk, while the remaining plant-based beverages fell far behind.

Median protein content was 3.10 percent for cow milk compared with 0.49 percent for the plant-based milks overall, a difference the authors report as statistically significant with p < 0.001. Plant-based milks showed higher catalase activity than cow milk, with a median of 42.67 versus 36.35 U/L (p = 0.002). At the same time, cow milk exhibited higher total oxidant status, 14.83 versus 9.19 µmol H₂O₂ Eq/L (p < 0.001), and a markedly higher oxidative stress index, 7.46 versus 1.80 (p < 0.001).

The dairy products thus carried both a heavier oxidant load and, relative to their antioxidant capacity, a less favorable oxidant-to-antioxidant ratio. To visualize how all these variables clustered across products, the researchers applied principal component analysis. The first two components together explained 65.3 percent of the total variance, with the first principal component accounting for 45.6 percent and the second for 19.7 percent.

By reducing the full panel of physicochemical and oxidative variables to a small number of composite axes, the analysis revealed the overall structure separating dairy from plant-based products and distinguishing among the plant alternatives themselves. The study went further with multivariable regression analysis to identify which parameter independently predicted the oxidative stress index. Catalase activity emerged as the strongest independent predictor, with a standardized coefficient of β = −0.141 and p < 0.001.

The negative sign indicates that higher catalase activity was associated with a lower oxidative stress index across the products, tying the enzymatic antioxidant measurements directly to the composite oxidative balance outcome. As an exploratory synthesis, the authors constructed a Global Antioxidant Quality Index combining the antioxidant and oxidative parameters. Hazelnut, soy, and oat milks scored highest on this index, placing them ahead of the other beverages in the comparison.

The authors label the index exploratory rather than a validated consumer metric, but it offers a compact summary of the multivariate findings: within the Turkish market sample, these three plant-based beverages combined measurable antioxidant capacity with comparatively low oxidative stress indicators. The authors conclude that the findings indicate substantial variation among plant-based beverages and suggest that some plant-based milks may exhibit a more favorable antioxidant-oxidative balance than conventional cow milk. The sample consisted of commercially available products in the Turkish market, so results may vary with brand formulation, fortification, and processing methods; the study accounted for processing by including both pasteurized and UHT cow milk.

The Global Antioxidant Quality Index is explicitly labeled exploratory. The article was received on 25 July 2026 and accepted on 24 September 2026, and is published open access under a CC BY license, with the authors noting that all claims expressed are their own and not necessarily those of their affiliated organizations or the publisher.

Subject of Research: Physicochemical characteristics, antioxidant capacity, and oxidative stress profiles of dairy and plant-based milks: a comparative multivariate analysis

Article Title: Physicochemical characteristics, antioxidant capacity, and oxidative stress profiles of dairy and plant-based milks: a comparative multivariate analysis

Article References: Kala, M. B., Yalçın, S., & Yalçın, S. S. (2026). Physicochemical characteristics, antioxidant capacity, and oxidative stress profiles of dairy and plant-based milks: a comparative multivariate analysis. Frontiers in Nutrition, 13, Article 1948308. https://doi.org/10.3389/fnut.2026.1948308

Image Credits: AI Generated

DOI: 10.3389/fnut.2026.1948308

Keywords: plant-based milk, dairy, antioxidant capacity, oxidative stress, catalase, food chemistry, nutrition, protein content, Physicochemical, characteristics, antioxidant, capacity