The importance of vitamin C in health has been known since the early 1900′s, and its value in human health is interesting, since humans are one of only a handful of mammals that are incapable of manufacturing this necessary vitamin ourselves. We must consume this potent antioxidant. Yet for all its health benefits, the same traits that contribute to its antioxidant properties also call into question how stable vitamin C is during food preparation and handling.
Is Vitamin C Stable To Cooking?
When most people think of vitamin C, the first thing that comes to mind is oranges, followed closely by every other citrus fruit on the planet. But even if you don’t like citrus, there are a number of foods that are rich sources of vitamin C. Peppers, blackcurrant, persimmon, brussel sprouts, and broccoli all outstrip oranges for vitamin C content. Unfortunately the potent antioxidant properties of vitamin C (also known as ascorbic acid) serves as a double-edged sword.
It has been known for some time that vitamin C is not entirely heat stable. When heated to temperatures above 70-degrees C (about 160 F), ascorbic acid (the chemical name for vitamin C) decomposes to dehydroascorbic acid. This decomposition process is accelerated by copper, iron, and oxygen; all abundant during food preparation. Toss in the fact that its also water-soluble, which means it leaches out of food when subjected to water, and it sounds as if it would be difficult to retain much of the vitamin C in cooked foods. It has even been shown that vitamin C levels in orange juice can vary wildly, depending on the age of the juice and whether it is fresh or frozen.
The flip side of this conundrum is the concept of “total vitamin C,” which is described as the sum of ascorbic acid and dehydroascorbic acid. There appears to be some merit to the idea that dehydroascorbic acid is also bioavailable. Research on vitamin C and the brain have shown your thinking cap to be rich in vitamin C, but also know this vitamin doesn’t cross the blood-brain barrier in the form of ascorbic acid. But rather, it crosses in the form of dehydroascorbic acid, and may even provide protection against stroke events. Interestingly enough, researchers at the Linus Pauling Institute have found dehydroascorbic acid to be a component of the popular supplement Ester-C.
So, despite the fact that vitamin C may not be entirely stable to cooking, it doesn’t appear that all is lost when it comes to cooking, or otherwise processing your foods, and still being able to get the benefits of vitamins. But there are some tips for cooking methods that will help ensure you retaining the greatest possible concentration of vitamins. Some of the suggestions include:
- Cook foods in the smallest amount of water possible. Recipes that include steaming or simmering tend to be the most amenable to this approach.
- Reduce cooking temperatures and times when possible, since high heat degrades vitamin C
- Baking is preferable to broiling.
- Cook potatoes whole in their skins.
- Store foods in airtight containers in the refrigerator.
- Do not store raw vegetables in water.
- Remember that vitamin C is not stable to oxygen either, so juices should be used 2-3 days.
Like many vitamins, we can safely say that vitamin C is not stable to the heat from cooking. However, this doesn’t necessarily mean cooking completely destroys its availability, either, since the oxidized form is also bioavailable. Combine this fact with proper cooking methods, and it seems apparent that most of the benefits of vitamin C are readily retained.
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