Key Takeaways
- High-heat extrusion, the process behind most dry kibble, can destroy up to 47% of vitamins and minerals before the food ever reaches a bowl, research suggests
- Heat sensitive nutrients like vitamin C, B vitamins and Omega-3 fatty acids break down easily, which is why many cooked foods rely on synthetic vitamins added back in afterwards
- Gentle processing methods, including freeze-drying and low-temperature steaming, preserve far more of a dog's natural nutrition than high-heat extrusion
- Home-cooked diets carry their own risks, with one veterinary study finding the vast majority of recipes tested were missing at least one essential nutrient
- Pawcredible's freeze-dried raw approach is built around locking in bioavailable nutrition rather than replacing what heat has destroyed
Dog food labels talk a good game. Words like "complete" and "balanced" sit proudly on the front of the bag, yet the way that food was made can quietly strip away much of what made it nutritious in the first place. For UK dog owners who read ingredient lists and want to understand what actually reaches their dog's bowl, the cooking method matters just as much as the ingredients themselves.
Extrusion Can Destroy Up to 47% of Nutrients, Studies Find
Most dry kibble sold in the UK is made using a process called extrusion, where ingredients are cooked under intense heat and pressure, often exceeding 200°C, before being shaped into the familiar biscuit form. Studies on this process have found it can destroy up to 47% of the vitamins and minerals present in the raw ingredients, while also lowering how digestible the remaining protein turns out to be. Vitamin C and various B vitamins are singled out in this research as particularly vulnerable to this kind of heat.
Brands like Pawcredible have built their entire approach around avoiding this problem, arguing that a food only counts as complete if a dog's body can actually use what's in it. That distinction between nutrients present on paper and nutrients a dog can absorb sits at the heart of the freeze-dried raw movement gaining ground across the UK.
How Heat Wrecks Vital Nutrients
Cooking has always been a trade-off. It can make food safer and easier to digest, but the higher the temperature and the longer the exposure, the more damage it tends to do to fragile nutrients, fat content, texture and even smell.
Vitamins and Minerals Lost to Extrusion
Findings on extrusion point to vitamin A, vitamin E and the B-group vitamins as especially sensitive to the high heat involved. Thiamine provides a striking example: one figure cited in the research shows retention decreasing from 90% to about 30% after heating. Vitamin C and Omega-3 fatty acids are reported to face similar losses, since both break down readily under sustained heat.
Studies Show Proteins Denatured, Amino Acids Reduced
Heat doesn't only affect vitamins. Research indicates proteins can become denatured during extrusion, meaning their structure changes in ways that reduce how usable they are. This matters because amino acids drawn from protein are understood to support muscle maintenance, immune defences and tissue repair. When that structure is compromised, a dog may be eating protein that looks fine on a label but delivers less than expected.
Why Manufacturers Add Synthetic Vitamins Back, Studies Find
Because so much is lost during high-heat processing, many manufacturers add synthetic vitamins and minerals back into the finished product to meet basic nutritional requirements. This keeps a food technically "complete" on paper, though some research suggests synthetic additions may not be as bioavailable as nutrients that occur naturally in whole ingredients.
Not All Cooking Is Equal
It would be unfair to paint every cooking method with the same brush. Temperature, duration and technique all shape how much nutritional value survives the process.
Research Shows Gentle Steaming Retains Over 90% of Antioxidants
Gentle, low-temperature methods such as steaming behave very differently to extrusion. One study found steaming can retain more than 90% of antioxidants while preserving vitamins A, C and E far more effectively than high-heat processing does. The difference comes down to time and temperature: shorter exposure at lower heat simply leaves more of the original nutrition intact.
When Research Shows Cooking Aids Digestibility
Cooking has upsides too. Findings from separate research show certain nutrients actually become more digestible once cooked. Albumin in egg whites is a good example, as is starch in carbohydrates, and cooking can break down cellulose in vegetables in ways that make them easier to absorb. The picture is nuanced rather than black and white.
Why Freeze-Drying Protects Bioavailability
Freeze-drying takes a different route entirely. Rather than applying heat, moisture is removed from raw ingredients at low temperatures, leaving the underlying nutritional structure largely undisturbed.
Locking In Enzymes, Amino Acids and Vitamins, Per Research
Because freeze-drying avoids high heat altogether, studies describe it as causing minimal nutrient loss compared with other drying or cooking methods. This body of research finds the process preserves proteins, amino acids, vitamins and minerals close to their raw state, while removing moisture in a way that also inhibits mould and bacterial growth without needing preservatives. Pawcredible applies this principle across its range, using a gentle freeze-drying process designed to lock in natural vitamins, minerals and enzymes exactly as they exist in the original ingredient, rather than rebuilding nutrition afterwards with synthetic additions.
Research Links Freeze-Drying to Firmer Stools, Steadier Energy, Stronger Immunity
Owners who switch to freeze-dried raw food often report firmer stools, steadier energy throughout the day and a visibly stronger coat. Other studies link raw and freeze-dried diets to improved digestion and immune support, pointing to the natural fatty acids and enzymes that survive the process. Freeze-dried raw formats also offer a practical advantage: dog owners get the nutritional profile of a standard raw diet without the mess or storage demands of handling raw meat at home.
The Risks of DIY Raw and Homemade Diets
Given how much heat can damage, it's tempting to assume home cooking or DIY raw feeding solves the problem entirely. In practice, it introduces a different set of risks.
Study Finds 95% of 200 Home-Cooked Recipes Lacked a Nutrient
A study from the University of California, Davis School of Veterinary Medicine analysed 200 homemade dog food recipes and found that 95% were deficient in at least one essential nutrient, with the majority lacking several. Even freshly cooked, human-grade meat-based meals often fall short on amino acids such as methionine and cysteine, along with calcium, zinc, iron, copper and various B vitamins, meaning supplementation is usually still required to get the balance right.
Vets Warn of Hygiene Hazards From Handling Raw Meat at Home
Handling raw meat at home also carries hygiene risks. The PDSA highlights the danger of cross-contamination with bacteria like E. coli and Salmonella, along with the extra care needed around storage, defrosting and surface cleaning. These are solvable problems with careful hygiene practices, but they add a layer of risk and effort that commercially prepared freeze-dried raw food is designed to remove.
Bioavailable Nutrition Beats Heat-Damaged Fillers
The throughline across all of this research is simple: how food is processed shapes how much of it a dog's body can actually use. High-heat extrusion can strip away a significant share of natural nutrition, gentle methods like steaming and freeze-drying preserve far more of it, and DIY approaches bring their own nutritional and hygiene pitfalls. For owners weighing up options, understanding the processing method behind a bag of food matters as much as reading the ingredient list itself.
For a practical next step, it's worth comparing labels with an eye on how the food was made, and considering freeze-dried raw dog food as a way to keep nutrition closer to its natural, bioavailable state.
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