My goal in writing this article is to share what you might not know about vitamins in the area of natural vs. synthetic and to touch on the subject of how vitamin supplements are produced. Keeping it short and to the point was no easy task.
What we call vitamin A is actually a group of compounds. Some called retinoids and others called carotenoids. Carotenoids are known as provitamin A because they can be converted into vitamin A. However, conversion of carotene to retinol varies from person to person and bioavailability of carotene in food also varies. Only the carotenoids alpha-carotene, beta-carotene, gamma-carotene and beta-cryptoxanthin can function as provitamin A.
Because vitamin A is fat soluble, a low fat diet can result in poor absorption of vitamin A. Fats increase the uptake of both carotenoids and retinoids.
A zinc deficiency can impair absorption, transport, and metabolism of vitamin A because zinc is essential for the synthesis of vitamin A transport proteins and as the cofactor in conversion of retinol.
Retinyl palmitate is the synthetically manufactured form of the vitamin. It can usually be converted to retinol, and ultimately to retinoic acid. However, acetone and other unhealthy chemicals are used in the process of making it.
Taking carotenoid supplements is the preferred form because the body will only convert them to retinoids as needed. However, taking retinoids in excess can be very dangerous because acute retinol toxicity could occur.
Vitamin B1, Thiamine
Vitamin B1 supplements can be made in three different ways:
Making synthetic vitamin B1 looks something like this: Hydrochloric acid is added to coal tar. Then fermentation, heating, cooling, and other steps are completed until the synthetic vitamin is created. It has a similar molecular structure but is not the same as the naturally occurring vitamin. This is currently the least expensive way to make the vitamin.
Food extracted vitamin B1 is made in a logical and natural way. The plant containing the vitamin is harvested, cleaned, and then put into a vat of water. After the vitamin has moved into the water, the fluid is filtered and the fiber is removed. The plant extract will contain the nutrients found in the original plant. This is the most expensive way to obtain the vitamin and also the form that our body uses best.
Another way so called ‘’natural’ vitamins are created is by growing yeast and then feeding the yeast synthetic vitamins. The yeast is then harvested and made into vitamin supplements. The theory is that the yeast will contain the vitamin it has been fed in a whole food complex. However, I tested this theory on myself. Every day for one year I consumed a B-Complex containing yeast that had been fed the synthetic form of vitamin B12, called cyanocobalamin. Then I took a test to see my B12 status. My white blood cells showed a deficiency of Vitamin B12. I am not sold on this method of vitamin production.
Vitamin B2, Riboflavin
Several biotechnological processes have been developed for manufacturing riboflavin. Different microorganisms are used including filamentous fungi (Ashbya gossypii, Candida famata and Candida flaveri) and bacteria (Corynebacteriumammoniagenes and Bacillus subtilis )
The bacteria bacillus subtilis has been genetically modified to increase its production of riboflavin and also to make it resistant to the antibiotic ampicillin. This form of manufactured riboflavin made from GMO bacteria treated with an antibiotic is now used for both animal feed and human food fortification. Natural food extracted B2 is obviously best with this vitamin.
Vitamin B3, Niacin
Nicotinic acid, the synthetic form of niacin, is created using coal tar, ammonia, and formaldehyde. It is less absorbable and has a greater risk of side effects than the natural form of the vitamin. However, nicotinic acid has been used for over 50 years to reduce low density lipoprotein cholesterol (LDL), very low-density lipoprotein cholesterol (VLDL-C), and triglycerides (TG), and to increase high density lipoprotein cholesterol (HDL). It has also been used to reduce the risk of cardiovascular events. 
Niaspan, available only by prescription, is an extended release form of nicotinic acid. It has a film coating that delays the release over a period of 8 – 12 hours. This can reduce the side effect of flushing but it increases the risk of liver toxicity.
Niacinamide, the flush free form of niacin found in food, does not dramatically reduce bad cholesterol or raise the good cholesterol, but can be synthesized in the human body from the amino acid tryptophan. Vitamin B6 is also required for the conversion of tryptophan to niacin, so low vitamin B6 status will impair this conversion. Niacin can also be extracted from plants for making supplements.
Vitamin B5, Pantothenic acid
Synthetic pantothenic acid is made with formaldehyde and isobutyraldehyde to form a calcium or sodium salt. Panthenol is the alcohol analog and acts as a provitamin for B5. I don’t recommend consuming any other form but food extracted B5.
Pantothenic acid derives its name from the Greek word pantothen, meaning “from everywhere”. Small amounts of pantothenic acid are found in almost every kind of food.
Vitamin B6, Pyridoxine
Synthetic Vitamin B6 – Pyridoxine hydrochloride is made from petroleum esters, hydrochloric acid, and formaldehyde. It may actually inhibit the action of natural B6 in the body. It also has side effects not normally found with natural food sources of this vitamin. Food extracted B6 is certainly best.
Pyridoxal-phosphate also known as PLP is the biologically active form of B6.
PLP is needed for almost all amino-acid-metabolism inside of our body, from synthesis to breakdown
Vitamin B7, Biotin
The process for making synthetic biotin was developed in the 1940s and uses fumaric acid as a starting material. Fumaric acid may be toxic with long term use. 
In humans, healthy intestinal bacteria produce biotin in excess of the body’s daily requirements. However, healthy intestinal bacteria is becoming rare as antibiotic use is on the rise.
Biotin is available in a wide range of food sources but few are particularly rich sources.
Vitamin B9, Folate
Folate is the naturally occurring form of vitamin B9 found in food. Folic acid is synthetically produced and needs to be converted to a human active form in order to be used. People with the MTHFR-677 genetic mutation have trouble making the conversion and making folic acid useable. If you have this mutation and supplement your diet with folic acid, you may be doing yourself a disservice. Un-metabolized folic acid can depress the immune system and lead to cancer or other kinds of disease that thrive in a body with a weak immune system.
There are also many manufactured forms of folate that are available, some are good and some are not. They are prescribed for raising folate levels in people with the MTHFR-677 mutation. Methylfolate is one of the better manufactured supplements for people with the MTHFR mutation.
Vitamin B12, Cobalamin
Vitamin B12 refers to a group of compounds called cobalamins that are found in the human body in different forms.
Naturally occurring B12, cobalamin, is a product of bacterial activity. Natural B12 is created by micro-organisms like the bacteria that grow in soil and in the intestines.
Cyanocobalamin is manufactured using the mineral cobalt and the toxin cyanide. They are fermented to make cyanocobalamin. People with the MTHFR mutation, (about 1 out of every 5 people) have great difficulty using this unmethylated form. What’s even worse, overuse can cause cyanide build up and become dangerous.
Hydroxocobalamin is not a form found in the human body, but can be converted in the body to a usable form of B12. This form is not yet methylated and needs to be in order to be useful.
Methylcobalamin is the type os vitamin B12 found in the human body and can be used to prevent or treat a vitamin B12 deficiency. Methylcobalamin is produced by certain bacteria or manufactured in a laboratory. This is the best human active form to use as a supplement because it is already methylated.
People with low stomach acid may have difficulty absorbing B12 from animal food because it comes bound to protein. Hydrochloric acid is needed in order to be able to remove the B12 from the protein.
Natural Choline can be extracted from sunflower seeds and is found in lecithin. Synthetic choline called choline chloride or choline bitartrate is made using ammonia, ethylene and hydrochloric acid or tartaric acid. I certainly opt for the food extracted form here.
Natural Vitamin C is found in nature in combination with bioflavonoids and phytonutrients that are important in its absorption and use. Synthetic Vitamin C, called ascorbic acid is isolated from genetically modified corn sugar that has been hydrogenated and processed with acetone. It does not include the bioflavonoids and phytonutrients that help it work.
Good sources for supplemental Vitamin C include camu camu, amla berry and acerola cherry.
The human body produces vitamin D3 when exposed to the sun. D3 is the most effective form of the vitamin.
Mushrooms produce the inferior form, D2. Synthetic vitamin D2 is made using ergosterol, a type of plant sterol derived from fungal cell membranes. Ergosterol is turned into viosterol by ultraviolet light, and then converted into ergocalciferol.
To make D3, the waxy secretion from sheep skin called lanolin is processed.
If you decide to supplement with vitamin D, I suggest lichen extracted D3. Lichens produce the same D3 that comes from human skin when exposed to the sun.
Vitamin E is made up of 8 different compounds: Alpha, beta, gamma and delta tocopherol and alpha, beta, gamma and delta tocotrienol. In synthetic vitamin E, they are only reproducing one part. It is called dl-alpha tocopherol. This analog is created using refined oils, trimethylhydroquinone, and isophytol. It is not as easily absorbed, doesn’t stay as long in tissues, and is quickly excreted like an unknown chemical.
Rice bran and annatto are excellent sources of the entire E complex.
There is K1 and K2. Natural Vitamin K1 is readily available in dark green leafy vegetables. Vitamin K2 is found in fermented food such as sauerkraut.
The synthetic vitamin K known as menadione comes from coal tar derivatives and genetically modified and hydrogenated soybean oil. They use hydrochloric acid and nickel in its production. It may actually damage the immune system among other unwanted side effects. In the United States, menadione supplements have been banned by the FDA because of their potential toxicity.
Once again, food extracted vitamin K is best.
Shockingly, the raw materials used for making synthetic vitamins can range from coal tar to petroleum and a long list of chemicals that one would never think of consuming. Synthetic supplements are made using chemical manipulations that duplicate the structure of isolated vitamins. Even worse, some supplements are produced by genetically altered bacteria because GMO bacteria can be made to produce vitamins. Unfortunately, formulas for these processes are not made available to the public. If they were, I am sure that it would reduce sales of synthetic vitamins and people would switch to food extracted vitamins.
 Stahmann KP, Revuelta JL and Seulberger H. Three biotechnical processes using Ashbya gossypii, Candida famata, or Bacillus subtilis compete with chemical riboflavin production. Appl Microbiol Biotechnol. 2000;53(5):509–516. doi:10.1007/s002530051649. PMID 10855708
 Villines, TC; Kim, AS; Gore, RS; Taylor, AJ (2012). "Niacin: The evidence, clinical use, and future directions".Current atherosclerosis reports 14(1): 49–59. doi:10.1007/s11883-011-0212-1. PMID 22037771
 Bruckert, E; Labreuche, J; Amarenco, P (June 2010). "Meta-analysis of the effect of nicotinic acid alone or in combination on cardiovascular events and atherosclerosis". Atherosclerosis210 (2): 353–61.doi:10.1016/j.atherosclerosis.2009.12.023. PMID 20079494
 "Biotin".HQhair.org. 2014-03-19. Retrieved 2014-03-19.
 European Commission: "European Commission Report of the Scientific Committee on Animal Nutrition on the Safety of Fumaric Acid". Retrieved 2014-03-07