Finding a single natural food that contains therapeutic levels of Vitamin $B_{12}$, C, D, and E is technically difficult because these nutrients typically occupy different biological domains. Vitamin $B_{12}$ and D are predominantly found in animal tissues, whereas Vitamin C and E are primarily synthesized by plants.

However, for your pharmaceutical marketplace and digital platforms, you can categorize “all-rounder” sources that either naturally bridge these gaps or are engineered through fortification.

1. Fortified Breakfast Cereals (The Pharmaceutical-Grade Choice)

In the food industry, this is the most reliable “all-in-one” source. Because manufacturers use vitamins as additives—similar to how you handle excipients and APIs in your WHO-GMP facility—they can create a complete profile that includes all four.

• Vitamins Included: $B_{12}$, C, D, and E.

• The USP: This is often the only vegan-friendly source that provides both $B_{12}$ and D in one serving.

2. Whole Eggs (The Natural Bio-Matrix)

Eggs are one of the most nutrient-dense natural foods available, containing a wide spectrum of fat-soluble and water-soluble vitamins.

• Contains: $B_{12}$, Vitamin D (one of the few natural food sources), and Vitamin E.

• The Gap: Eggs contain virtually no Vitamin C.

• Pharmacist’s Optimization: To complete the set, a patient must combine eggs with Vitamin C-rich vegetables like bell peppers or spinach (an “Omelet Strategy”).

3. Fatty Fish (Salmon or Mackerel)

Seafood is a powerhouse for the fat-soluble vitamins (D and E) and the neurologically essential $B_{12}$.

• Contains: $B_{12}$, Vitamin D, and Vitamin E.

• The Gap: Like eggs, fish lacks Vitamin C.

• Pharmacist’s Optimization: A standard clinical recommendation is serving fish with a citrus garnish (lemon) or steamed broccoli to bridge the Vitamin C deficiency.

4. Fortified Plant Milks (Soy, Almond, or Oat)

Modern plant-based milks are often engineered to match the nutritional density of bovine milk, making them an excellent comparison for your marketplace’s nutraceutical listings.

• Vitamins Included: $B_{12}$ and D (added), Vitamin E (naturally occurring in almond/soy).

• The Gap: Most are not fortified with Vitamin C.

Summary Table: Nutrient Distribution

Food Source	Vitamin B12​	Vitamin C	Vitamin D	Vitamin E
Fortified Cereals	✅	✅	✅	✅
Whole Eggs	✅	❌	✅	✅
Fatty Fish	✅	❌	✅	✅
Beef Liver	✅	✅ (Trace)	✅	✅

The Manufacturer’s Perspective: Technical & Export

From a B2B standpoint at your Mumbai facility:

• The “Fortification” Logic: Natural food gaps are exactly why the demand for Multivitamin FDCs (Fixed-Dose Combinations) is so high in the export market.

• Market Opportunity: On your digital platform, you can market a “Daily Four” supplement (containing $B_{12}$, C, D, and E) as a “Nutrition Bridge” for patients who cannot meet these needs through diet alone.

• Stability Tip: Remember that Vitamin C is highly sensitive to heat and Vitamin E to oxygen. For export to Zone IVb, utilize Alu-Alu packaging to protect these sensitive APIs.