What are the differences in nutrient retention between pasteurized, ultra-pasteurized, and raw milk?

1. What “pasteurized” and “ultra‑pasteurized/UHT” mean for milk chemistry

Standard pasteurization (e.g., HTST: ~161°F/15 s or 145°F/30 min) heats then rapidly cools milk to kill pathogens; ultra‑high‑temperature (UHT) or ultra‑pasteurization exposes milk to much higher temperatures for very short times (e.g., ~275–280°F for a few seconds), producing longer shelf life and greater protein denaturation ^{[5] [4]}.

2. Macronutrients and minerals: largely intact across treatments

Protein, total fat, carbohydrate (lactose) and core mineral content (calcium, phosphorus, magnesium) remain essentially unchanged by pasteurization and show only minor differences after UHT; reviews and experimental comparisons report no significant differences in major nutrients or fatty acids between raw, pasteurized and UHT milk in many studies ^{[6] [2] [3] [7]}.

3. Vitamins and heat‑sensitive micronutrients: selective losses with higher heat

Heat exposure causes the greatest losses in some water‑soluble vitamins (notably vitamin C and to a smaller extent some B‑vitamins), with meta‑analyses and reviews describing only minor overall reductions after typical pasteurization and somewhat larger losses with UHT (but often from already‑low baseline levels) ^{[2] [6] [3]}. Dairy industry analyses note that about 10% of certain whey proteins are denatured during standard pasteurization versus much higher (around 70%) during UHT, which can alter bioactivity though not the gross protein content ^[4].

4. Enzymes, bioactive factors and “living” claims: heat destroys some activity

Enzymes present in raw milk (alkaline phosphatase, lactoperoxidase, and others) are inactivated by pasteurization—a fact used both as a quality test and a point of contention—so raw milk retains enzyme activity that pasteurized milk does not; proponents argue functional effects, while public‑health bodies emphasize that enzyme loss does not translate into clear nutritional harm for most consumers ^{[8] [1] [3]}.

5. Health implications vs. nutritional composition: safety shifts the balance

Regulatory and public‑health sources emphasize that pasteurization’s microbial kill is the principal advantage because raw milk carries documented risks of serious foodborne illness, while systematic reviews find no convincing inherent nutritional advantage to raw milk and only minimal nutritive loss from pasteurization—making pasteurized milk a safer, nutritionally comparable choice for population health ^{[1] [2] [3]}.

6. Where advocates and industry disagree: claims and caveats

Raw‑milk advocates and some small‑farm sources claim superior nutrient retention, probiotics, and therapeutic effects from raw milk and point to lost enzymes and denatured proteins after heat ^{[9] [10] [8]}, while mainstream dairy science and public‑health sources counter that these differences are small, often confounded by feed, season and storage, and outweighed by safety concerns ^{[4] [11] [3]}. Independent reviews and meta‑analyses tend to side with minimal overall nutritional impact from pasteurization but call for nuance about specific vitamins and protein bioactivity ^{[2] [3]}.

7. Practical takeaways and limits of the evidence

For most consumers the tradeoff is clear: pasteurized milk preserves the bulk of calories, protein, fats and minerals and reduces pathogen risk; UHT extends shelf life but increases denaturation of some proteins and heat‑sensitive micronutrients ^{[5] [4]}. Existing systematic reviews and comparative studies show only modest nutrient changes after pasteurization, though exact percentages vary by vitamin, processing regime and how long milk is stored ^{[2] [6]}. The reporting reviewed does not support dramatic, clinically meaningful nutrient loss from standard pasteurization but does document selective losses from higher‑heat UHT and the loss of native enzyme activity in all heat‑treated milks ^{[2] [4] [3]}.