Top 7 Fortified Vitamin & Mineral Diets in the United States for 2025: A Veterinarian-Reviewed Guide to Supporting Small Pets' Bone, Coat and Immune Health

Oxbow Essentials Adult Guinea Pig Food is positioned as the best-in-class choice for vitamin C–fortified diets, thanks to its timothy-hay base and strict quality control that prioritize natural fiber and nutrient stability. It commands a premium price but delivers superior nutrient bioavailability and hay-forward formulation compared with more heavily processed or budget-focused options like Living World and Kaytee. For owners prioritizing long-term health and fiber quality in vitamin C–fortified feed, Oxbow’s technical consistency and ingredient sourcing set it apart.

Mazuri Timothy-Based Rabbit Diet is a zoo- and institutional-grade feed prized for its precise nutrient formulation and consistent calcium-to-phosphorus balance, making it a top choice where controlled calcium supplementation matters. Compared to garden-variety mixes and consumer brands, Mazuri’s technical advantage is its extruded pellet uniformity and formulation rigor used by professionals — a premium option that typically costs more but reduces nutrient variability for breeders and clinics.

Oasis Vita-Drops Pure C stands out as a technically efficient and cost-effective solution for delivering concentrated vitamin C in drop form, which can be easily added to water or applied to food for small pets that refuse powders or tablets. Compared with the powdered multivitamins listed here, its liquid delivery often provides faster absorption and a lower cost per milligram of vitamin C, though it lacks the broader micronutrient spectrum some powders provide.

Oxbow Critical Care Herbivore is the category's herbivore-focused leader, formulated as a fiber-rich, easily syringeable paste tailored to rabbits, guinea pigs and other small herbivores. It holds its position through a veterinary-grade fiber profile and palatability that support gut motility better than general high-calorie gels like Vetoquinol Nutri-Cal, while being more species-targeted than broad-market options such as Tomlyn or Kaytee.

Oxbow Natural Science Vitamin C Support leverages the company's research-driven approach to small herbivore nutrition, combining vitamin C with complementary dietary considerations to support animals with higher clinical needs. Although it typically commands a premium price versus simpler water drops, its technical advantage is formulation synergy with Oxbow feeds and husbandry guidance, offering tangible value for owners committed to an integrated nutrition plan. Compared with single-ingredient drops like Oasis, Oxbow is less about minimalism and more about structured, science-backed supplementation.

Supreme Science Selective Rabbit Food with Linseed uses linseed to supply natural omega oils and a selective pellet system that reduces waste and encourages healthy coat condition. It's a market leader for rabbits seeking a balance of palatability and targeted fatty acids, offering a technical advantage over plain timothy blends while typically positioned at a higher price point.