Vitamins come largely from the food you eat. Progress in medical science makes it possible to isolate the pure vitamins and take them for use in pills and tablets, allowing you to avoid deficiencies while abstaining from food sources you might not enjoy eating. But divorcing vitamins from their protein complexes can lead to problems. In the case of fat-soluble vitamins, one of the most serious problems is liver damage.
Definition
"Vitamin isolate" refers to synthetic vitamins that you take as a supplement. They have been isolated from the food-vitamin complexes of joined minerals and enzymes in which they naturally occur. Not all supplement-form vitamins are isolates. Some are designated "whole-food" supplements and are created by extracting the entire food-vitamin complex from its food source. But not every supplement labeled as "whole-food" truly is such. Check the ingredient from which the manufacturer derived the vitamin to be sure. For instance, the Organic Consumers Association says that if a vitamin A supplement's source is fish oils, it's natural, but if the source listed is acetate or palmitate it's synthetic -- an isolate.
Reduced Absorbency
The body has an easier time digesting food-vitamin complexes than it does isolates. The attached proteins act as a sort of "chaperone," as Nobel Prize winner Dr. Gunter Blobel put it. He proved in 1999 that this chaperone protein is the key to getting the vitamin into the bloodstream. HealthGuidance.org mentions studies which have demonstrated only 10 percent absorption of vitamin isolates compared to 77 to 93 percent absorption of food-vitamin complexes.
Excessive Doses
Synthetic vitamin supplements often contain an excessive amount of the vitamin chemical to make up for the low absorption rate. The Organic Consumers Association mentions vitamin C tablets labeled at 1,000 percent of the recommended daily allowance. Fortunately, vitamin C is water-soluble; any unused vitamin molecules wind up in the toilet rather than building up inside your body.
Hepatoxicity
Unused portions of fat-soluble vitamins can accumulate in the fat tissues, fat deposits and the liver. Build-up in the liver presents a risk of hepatoxicity, or poisoning of the liver. Liver poisoning is especially a risk with high doses of synthetic vitamins because of the difficulty absorbing them. When little of the chemical passes into the bloodstream, more of it builds up in the liver.
Vitamin A
Vitamin A is a classic example of a synthetic -- in this case retinol -- which is toxic to the liver at high doses. Habitually taking doses at 10 times the recommended daily allowance leads to hypervitaminosis, or vitamin poisoning. Symptoms of vitamin A poisoning, according to the ExRx.net website, include anorexia, headache, pain in the bones and muscles, vomiting, liver damage and coma.
Plant-based vitamin A poses no danger of overdose. Unlike the isolated chemical retinol, excessive amounts of its precursor beta-carotene at worst cause a yellowing of the skin in the fatty areas of the hands.
Vitamin B
According to Dr. Robert J. Thiel, the isolated forms of the various B vitamins are less effective than their food-based counterparts. Although the liver retains a higher proportion of some food-based B vitamins than of the isolated supplements, the food-based complexes pose less of a risk of hepatoxicity. For example, Dr. Thiel says that vitamin B3's food-based form, niacinamide, seems to cause less hepatoxicity and fewer other side effects than synthetic time-released niacin.
References
- Organic Consumers Association: Background Info on Synthetic vs. Natural Vitamins
- Health Guidance: How to Choose a Good Vitamin Supplement
- Hepatitis Foundation International: Caring for Your Liver
- ExRx.net: Vitamin A
- Heise Health Clinic: Natural B Vitamins Are Better Than Synthetic Ones
- NutriTeam.com: How to Read Labels
