Vitamins 101: Functions, Types & Sources

Vitamins are Essential for Life

Vitamins are necessary for our bodies to function. They are cofactors that participate in the millions of biochemical reactions that happen in our bodies every day. We get vitamins through various types of foods that we eat, especially colorful, whole, non-processed foods. Although foods are a good source of vitamins, additional supplemental vitamins and minerals are often needed. Poor farming and food supply practices deplete soils of vitamins and make the food less nutritious. Increased pollution in our environment and increased stress in our day-to-day life increases our bodies’ usage of vitamins.  Below is a list of each vitamin, its function in the body, and what foods have the highest concentration of that particular vitamin.

Vitamins can be divided into two categories: fat-soluble and water-soluble. 

Fat-Soluble Vitamins

Fat-soluble vitamins are best absorbed when eaten with fatty food. Excess vitamins can also be stored in our fatty tissue, so eating too many of the fat-soluble vitamins can accumulate and become a burden to our body. Below are examples of some foods that have a higher concentration of each vitamin (this is not a complete list). 

 

Vitamin A; Beta-Carotene

vitamin a beta carotene sources

Essential for normal growth, tissue growth and maintenance, tooth development, night vision, healthy eyes, and normal bone development.

Sources of Vitamin A: 

  • Apricots
  • Cantaloupe
  • Peaches
  • Carrots
  • Liver
  • Egg yolk
  • Yellow and Dark Green leafy vegetables

 

Vitamin D (calciferol)

vitamin d sources

A prohormone for normal growth and development, normal bones and teeth, absorption and

metabolism of calcium, phosphorus and magnesium.  Prevents osteoporosis (weak bones) and osteomalacia (softening of bone).

Sources of Vitamin D:

  • Sardines
  • Vitamin D milk
  • Liver (some)
  • Egg yolk
  • Tuna
  • Salmon
  • Sunlight converts 7-dehydrocholesterol to cholecalciferol (D3)

 

Vitamin  E (tocopherol)

vitamin e sourcesIt is a strong antioxidant.  Protects red blood cells from hemolysis (destruction), has a role in reproduction, tissue maintenance and prostaglandin synthesis. 

Sources of Vitamin E:

  • Wheat germ
  • Nuts & seeds
  • Vegetable oils
  • Milk fat
  • Egg yolk
  • Green leafy vegetables

 

Vitamin K (phylloquinone)

vitamin k sourcesAids in prothrombin production, which is required for normal blood clotting. 

Sources of Vitamin K:

  • Soybean oil
  • Vegetable oils
  • Wheat Bran
  • Liver
  • Dark green leafy vegetables

Water-Soluble Vitamins

Water-soluble vitamins can usually be taken with or without food. Excess water-soluble vitamins are simply eliminated through our urine, so they do NOT accumulate to toxic levels. Below are examples of some foods that have a higher concentration of each vitamin (this is not a complete list). 

 

Thiamin; B1

thiamin vitamin b1 sourcesPrevents beriberi.  Aids in carbohydrate metabolism.  Essential for growth, normal appetite, digestion, and healthy nerves. 

Sources of Vitamin B1:

  • Potatoes
  • Wheat germ
  • Organ meats
  • Pork
  • Whole grains

 


Riboflavin; B
2

riboflavin vitamin b2 sourcesFor growth, healthy eyes, tissue respiration, transportation of hydrogen ions, coenzyme forms FMN and FAD.  Prevents fissures at corners of mouth, nose, and ears, eye irritation, and photophobia. 

Sources of Vitamin B2:

  • Enriched cereals
  • Milk & Dairy foods
  • Organ meats
  • Bread
  • Eggs
  • Green leafy vegetables

 

Niacin; B3

niacin vitamin b3 sourcesPart of an enzyme system for transfer of hydrogen, metabolism of amino acids and carbohydrates.  Prevents pellagra, nervous depression, and neuritis needed in fat synthesis and tissue respiration.  Synthesized by intestinal bacteria.

Sources of Vitamin B3:

  • Peanuts
  • Legumes
  • Milk
  • Fish
  • Liver
  • Meat
  • Poultry
  • Many grains
  • Eggs

 

Vitamin B6 (pyridoxine)

vitamin b6 sourcesA coenzyme in the breakdown and synthesis of amino acids and in the synthesis of unsaturated fatty acids from essential fatty acids.  Conversion of tryptophan to niacin.  Prevents hypochromic anemia, seborrheic dermatitis, mucous membrane lesions and peripheral neuritis.  Essential for normal growth, neurotransmitter synthesis and gynecological health.  Synthesized by intestinal bacteria.

Sources of Vitamin B6:

  • Cereal bran & germ
  • Glandular meats
  • Pork
  • Milk
  • Egg Yolk
  • Oatmeal
  • Legumes


Folic Acid

folic acid sourcesEssential for the synthesis of genetic material and normal maturation of all cells, including red blood cells.  Related to macrocytic anemia.  Synthesized in the intestinal tract.

Sources of Folic Acid:

  • Lentils
  • Cowpeas
  • Asparagus
  • Broccoli
  • Collards
  • Yeast
  • Organ meats
  • Beef
  • Wheat
  • Eggs
  • Fish
  • Dry beans
  • Green leafy vegetables


Vitamin B
12

vitamin b12 sourcesMetabolism of single carbon fragments, synthesis of genetic material, red blood cell formation, nervous tissue metabolism.  Related to certain anemias (pernicious and macrocytic.)  Related to normal growth.  Synthesized by intestinal bacteria.  Some feel vegans require supplementation.  Injections required by those whose stomachs don’t produce enough intrinsic factor (a substance required to absorb B12 in the small intestine).

Sources of Vitamin B12:

  • Liver
  • Kidney
  • Milk & Dairy foods
  • Meat
  • Eggs

 

Vitamin B5 – Pantothenic acid

vitamin b5 sourcesAs part of coenzyme A, functions in the breakdown and synthesis of many vital body compounds.  Intermediate metabolism of carbohydrates, protein and fat.  It may be synthesized by intestinal bacteria.

Sources of Vitamin B5:

  • Present in all plant and animal foods
  • Eggs
  • Kidney
  • Liver
  • Salmon
  • Yeast


Biotin

Biotin sourcesSynthesis and breakdown of amino acids, aids in addition or removal of CO2, removal of NH3.  Closely related metabolically to folic acid and pantothenic acid.  Synthesized in the intestine.

Sources of Biotin:

  • Liver
  • Mushrooms
  • Peanuts
  • Yeast
  • Most vegetables
  • Banana
  • Grapefruit
  • Tomato
  • Watermelon
  • Strawberries


Vitamin C (Ascorbic acid)

Vitamin C sourcesEssential for growth.  Metabolism of amino acids (especially tyrosine and phenylalanine), conversion of folic acid to folinic acid.  Essential for many hydroxylation reactions.  Role in tooth and bone formation, connective tissue integrity, and capillary integrity.  Promotes healing of wounds and fractures and reduces the chance of infections.  Essential for the production of collagen, antioxidant, biosynthesis of steroid hormones and prevents scurvy.

Sources of Vitamin C:

  • Puerto Rican cherry
  • Citrus fruit
  • Tomato
  • Melon
  • Peppers
  • Raw cabbage
  • Greens
  • Guava
  • Strawberries
  • Pineapple
  • Potato


Conclusion:

The quality of the Vitamins matter. Certain forms of vitamins are more easily absorbed in the body than other forms. It is also important to see what else is in the supplement; are there any additional ingredients like preservatives and fillers that do not need to be there. Since the Vitamin industry is not well regulated, we get companies that produce products that do not absorb into the body. Other companies take efforts to test and retest their products to ensure that what you are getting is safe, good and absorbable. You could also check with your holistic practitioner to make sure the brand you are using is a good one.

 

References

Food, Nutrition & Diet Therapy, 7th Edition, Krause & Mahan, W.B. Saunders Company, Philadelphia, 1984.

This article was adapted from Bastyr University Natural Health Clinic

 

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