Isotonic vitamins are rapidly absorbed, and fast absorption is beneficial for energy production and quick rehydration during intense activities. But when you’re supplementing with vitamins and minerals, rapid absorption doesn’t always mean it’s a better supplement or that you’ll get more of the nutrients. If you have any questions or health concerns, consult a doctor about your vitamin options.
Water inside your body circulates through three distinct compartments -- inside cells, outside cells and inside blood vessels. Each compartment is separated by a membrane that lets water go through but blocks some molecules. The amount of dissolved molecules in the fluid on each side of a membrane determines whether water flows in or out of a compartment.
An isotonic solution is one that contains the same amount of dissolved particles that is normally found in body fluid. This equal concentration allows fluids to freely flow from one compartment to the next.
Isotonic Supplement Advantage
Like any isotonic solution, the advantage of taking isotonic vitamins is that the nutrient-carrying fluid can easily flow through membranes. This should increase the rate of nutrient absorption, but other variables affect digestion and absorption, so there's no guarantee your isotonic supplement will be better than other types of supplements.
Most liquid supplements -- isotonic or not -- are absorbed a little faster than tablets, reports All Star Health. Another factor is the type of vitamin in your isotonic solution.
For example, fat-soluble vitamins won't be absorbed well unless the supplement is taken together with some fats or food. Many brands of isotonic vitamins suggest taking it on an empty stomach. That may boost the rate of absorption for some nutrients, but it won't help fat-soluble nutrients.
Benefits From Isotonic Sports Drinks
Isotonic sports drinks are used to quickly replace electrolytes and water lost through heavy sweating. Sports drinks consisting of about 6 percent to 8 percent carbohydrate are considered to be isotonic, according to Brian Mac Sports Coach.
Isotonic sports drinks may have benefits beyond fast hydration. Researchers conducted a study in which healthy young men visited the lab several times to engage in monitored exercise. When the participants consumed isotonic beverages, their heart rate recovered faster after the activity ended than it did when they exercised without drinking an isotonic supplement, reported the Journal of the International Society of Sports Nutrition in January 2013.
Tips and Considerations
In medical settings, isotonic fluids are often used to replace fluids. They’re also precisely measured, which is important to remember if you buy isotonic vitamins. Isotonic supplements are sold as powders and mixed with water. As one brand notes on the label, you must use the exact amount of powder and water called for in the directions to be sure your supplement is isotonic.
Some nutrients, including vitamin C, calcium, iron, folic acid and several B vitamins, are actively transported through the wall of the small intestine. Since the intestine contains a limited number of transporters, supplements that quickly flood the small intestine may overwhelm transporters. As a result, some nutrients will be eliminated rather than absorbed.
- Austin Community College: Fluid/Electrolyte Balance
- All Star Health: Sorting Out Supplements: Tablets vs. Capsules vs. Liquids vs. Powders vs. Chewables
- Brian Mac Sports Coach: Sports Drinks
- Journal of the International Society of Sports Nutrition: Effects of an Isotonic Beverage on Autonomic Regulation During and After Exercise
- Southern Illinois University School of Medicine: Nutrient Absorption