Essential Vitamins: Sources and Synthesis

Here’s a comprehensive list of all essential vitamins needed by the human body, their functions, vegetarian food sources, whether the body can produce them, and dependencies on other nutrients:

1. Vitamin A (Retinol, Beta-Carotene)

Function: Vision, immunity, skin, reproduction.
Veg Sources: Carrots, sweet potatoes, spinach, kale, pumpkin, mango, papaya.
Body Can Produce: No, but beta-carotene from plants converts to Vitamin A.
Dependency: Requires fat for absorption.

2. Vitamin B1 (Thiamine)

Function: Converts carbs to energy, nerve function.
Veg Sources: Whole grains, legumes (lentils, beans), nuts, seeds, fortified cereals.
Body Can Produce: No.
Dependency: Works well with other B-complex vitamins.

3. Vitamin B2 (Riboflavin)

Function: Energy production, skin, vision, red blood cell formation.
Veg Sources: Almonds, mushrooms, spinach, whole grains, fortified cereals.
Body Can Produce: No.
Dependency: Helps activate B6 and folate.

4. Vitamin B3 (Niacin)

Function: Energy metabolism, skin health, DNA repair.
Veg Sources: Whole grains, peanuts, mushrooms, green peas, legumes.
Body Can Produce: Yes, from tryptophan (an amino acid).
Dependency: Needs B6 and iron for synthesis from tryptophan.

5. Vitamin B5 (Pantothenic Acid)

Function: Hormone synthesis, metabolism.
Veg Sources: Avocados, sweet potatoes, broccoli, whole grains, mushrooms.
Body Can Produce: No.
Dependency: Works with other B vitamins.

6. Vitamin B6 (Pyridoxine)

Function: Brain development, immunity, neurotransmitter production.
Veg Sources: Bananas, potatoes, chickpeas, whole grains, sunflower seeds.
Body Can Produce: No.
Dependency: Works with B12 and folate.

7. Vitamin B7 (Biotin)

Function: Hair, skin, nail health, metabolism of fats and proteins.
Veg Sources: Nuts, seeds, sweet potatoes, spinach, broccoli.
Body Can Produce: Yes, by gut bacteria.
Dependency: Antibiotic use may reduce natural production.

8. Vitamin B9 (Folate/Folic Acid)

Function: DNA synthesis, pregnancy health, red blood cell formation.
Veg Sources: Spinach, kale, broccoli, lentils, chickpeas, oranges.
Body Can Produce: No.
Dependency: Works with B12 and vitamin C.

9. Vitamin B12 (Cobalamin)

Function: Nerve function, red blood cell production, DNA synthesis.
Veg Sources: None naturally. Found in fortified foods like cereals, nutritional yeast, plant milks.
Body Can Produce: No.
Dependency: Needs intrinsic factor (from stomach) for absorption.
Note: Must supplement in vegetarian/vegan diets.

10. Vitamin C (Ascorbic Acid)

Function: Antioxidant, collagen synthesis, immunity, iron absorption.
Veg Sources: Oranges, amla, guava, kiwi, bell peppers, tomatoes, strawberries.
Body Can Produce: No.
Dependency: Enhances iron absorption.

11. Vitamin D

Function: Bone health, calcium absorption, immunity.
Veg Sources: Fortified foods (soy milk, cereals, mushrooms exposed to UV).
Body Can Produce: Yes, via skin when exposed to sunlight (UVB).
Dependency: Needs fat and magnesium for activation.

12. Vitamin E (Tocopherol)

Function: Antioxidant, skin and eye health, immune support.
Veg Sources: Sunflower seeds, almonds, spinach, avocados, vegetable oils.
Body Can Produce: No.
Dependency: Needs fat for absorption.

13. Vitamin K

Function: Blood clotting, bone metabolism.
Veg Sources: Green leafy vegetables (spinach, kale), broccoli, cabbage, soybeans.
Body Can Produce: Yes, partially by gut bacteria.
Dependency: Fat-soluble, needs fat for absorption.

Summary Table

Vitamin	Body Makes It?	Needs Other Nutrients	Key Veg Sources
A	From beta-carotene	Fat	Carrots, spinach
B1	No	B-complex synergy	Whole grains, legumes
B2	No	Helps activate B6, B9	Almonds, spinach
B3	From tryptophan	Needs B6, Iron	Peanuts, mushrooms
B5	No	-	Avocados, mushrooms
B6	No	Works with B9, B12	Potatoes, bananas
B7	Yes (gut)	Affected by antibiotics	Nuts, broccoli
B9	No	Needs B12, C	Leafy greens, lentils
B12	No	Needs intrinsic factor	Fortified foods only
C	No	Helps absorb iron	Citrus, bell peppers
D	Yes (from sunlight)	Needs fat, magnesium	Sunlight, fortified foods
E	No	Needs fat	Seeds, avocados
K	Partially (gut)	Needs fat	Leafy greens

How to Check Intrinsic Factor in the Stomach

To check intrinsic factor levels in the stomach, doctors typically use a blood test called the Intrinsic Factor Antibody Test. Here’s how it works and what you should know:

1. What is Intrinsic Factor?

It’s a protein produced by parietal cells in the stomach.
It's essential for the absorption of vitamin B12 in the small intestine.

2. How to Test for Intrinsic Factor?

A. Intrinsic Factor Antibody Test (IFA) – Blood Test

Purpose: Detects antibodies that block or destroy intrinsic factor.
Used to Diagnose:
- Pernicious anemia (a condition where B12 absorption is impaired due to lack of intrinsic factor).
Result Meaning:
- Positive: Your immune system is attacking intrinsic factor → likely pernicious anemia.
- Negative: No such antibodies, but doesn’t rule out all forms of B12 malabsorption.

B. Schilling Test (Rarely Used Now)

Old test: Radioactive B12 was given to see if the body absorbed it with/without intrinsic factor.
Rarely used today due to complexity and radioactive material.

C. Gastric Biopsy (In Special Cases)

Done during endoscopy.
To check parietal cell damage or atrophy (can cause intrinsic factor deficiency).

3. When to Get Tested?

If you have:

Unexplained vitamin B12 deficiency
Neurological symptoms (tingling, memory issues)
Fatigue or anemia
Vegetarian for many years without supplementation
Family history of autoimmune conditions

4. Where to Get It Done?

Any major diagnostic lab (like Thyrocare, SRL, Dr Lal PathLabs, etc.)
Ask for: Intrinsic Factor Antibody Test
It may be included in a B12 deficiency workup panel

Key Vitamins Needed by Humans: Vegetarian Foods and Body Production

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