Many people with corn allergy or intolerance look forward to this time of year because of Passover. With the arrival of Kosher for Passover foods in grocery stores, our food options suddenly become broader, at least for a few weeks out of the year. Many products that are normally made with corn are suddenly available in corn-free versions.
But Passover doesn't mean we can throw caution to the wind and eat anything with a "Kosher for Passover" label. There are a couple of things a corn-avoider needs to know when it comes to Kosher for Passover certification.
First, not all certifying agencies are equal. Different agencies have different standards for what is or is not considered Kosher for Passover. Some Jews avoid kitniot (legumes and small grains that can be ground into flour and swell when wet, including corn) at Passover, and others don't. A product certified Kosher for Passover by an agency that allows kitnitot at Passover is no help at all from a corn-allergy standpoint.
Here are a couple of lists showing some of the different heschers, or marks, from certifying agencies that indicate a product has been produced under kosher supervision.
If a product is Kosher for Passover, the letter P will be added to the hescher (as in OU-P) or the words "Kosher for Passover" or "for Passover Use" or something like that will be on the label. Please note that Kosher Pareve is NOT the same thing as Kosher for Passover. Pareve simply means that an item contains neither meat nor dairy.
You will have to check regarding each certifying agency to find out whether they require that products be kitniot-free to be certified Kosher for Passover or not. The OU (Orthodox Union), OK (Organized Kashrus Laboratories), Star-K, The Kashruth Council of Canada (the hescher looks like a circle with COR inside) and the cRc are a few that certify only kitniot-free foods as Kosher for Passover.
Since most Jews in the USA are of European ancestry and do not eat Kitniot on Passover, a majority of US Kashruth organizations today do not certify foods with kitniot as Kosher for Passover.
It may not always be necessary to check up on each hescher. Most stores that carry a Kosher for Passover selection should be able to tell you whether they carry only kitniot-free products or not. Many in the USA carry only kitniot-free products, or separate the products containing kitniot from those that do not. The local kosher grocery in my area carries only a few products containing kitniot, and they are clearly labeled with "contains kitniot" warning stickers. The manager there is well-versed in which heschers are kitniot-free and is careful to make them easily distinguishable to the buyer.
However, even among organizations that certify only kitnios-free foods as Kosher for Passover, there are variations. Many or most of these allow certain kitnios derivatives in even kitnios-free foods. Some, for instance, consider corn oil and certain other corn derivatives to be allowable even though corn flour or corn itself would be considered kitnios. The kitniot or non-kitniot status of peanuts is especially debated, and many traditions do not consider peanut oil to be kitniot.
There is a certain rule regarding kitnios, that if it has been sufficiently changed in nature it is no longer kitnios for kosher purposes. This change must include both the chemistry and the taste of the product. Some organizations require that it must become inedible at some point in the process to qualify as shenistanu or nishtaneh ha’teva ("changed nature"), while others do not.
The "changed nature" rule is particularly applicable to corn. It is rather common for certifying agencies to allow products developed via fermentation processes to use corn syrup as a growth medium.
The OU, for example, certifies some products (particularly fermentation products) Kosher for Passover if they were grown on chometz-free corn syrup. These can be produced using corn-derived corn syrup, dextrose, or glucose as raw ingredients, but the final product may still be certified Kosher for Passover.
The following list of corn derivatives that can be considered Kitniyos Shenistanu or nishtaneh by many organizations is compiled from the following websites: VAAD (council of rabbis) of Montreal, Kashrut.com, and Scroll-K, the OK, the OU, and Star-K:
Ascorbic acid, artificial sweeteners, aspartame, calcium ascorbate, citric acid, glucosamine hydrochloride, Nutra-Sweet, maltodextrin, microbial rennet, MSG (monosodium glutamate), sorbitan, sorbitol, sodium ascorbate, sodium citrate, sodium erythorbate, yeast (some nutritional or brewer's yeasts can be Kosher for Passover), xanthan/xantham gum, vanillin (from rice), Vitamin C.
Even ingredients in this list, though, very well may not be corn-derived in Kosher for Passover products. Individual manufacturers may make the choice to use non-kitniot alternatives even if the certifying agency allows kintiot derivatives. For instance, many people on the Delphi Corn Avoiders Forum have been using OU-P certified Kosher for Passover products with very few reactions. It's always a good idea to check on the forums to find out which products have been tried by others of similar sensitivity, and whether there have been reported reactions or not.
As far as I can tell from their websites, the OK, Star-K and scroll K agencies seem to take a more stringent position on kitniyot derivatives than do some of the other organizations.
The OK website talks quite a lot about how they have been instrumental in making available truly Kosher for Passover ingredients such as citric acid grown on cane sugar. They include the following list of products that are not readily available in truly Kosher for Passover form, but for which they have found alternative kitniot-free sources:
Sodium Citrate, Tri-Calcium Citrate, Residual Fuse Oil (natural), Iso-Amyl Alcohol (natural), Acetic Acid (natural), Ethyl Acetate (natural), Iso-Amyl Acetate (natural), Ethyl Alcohol.
I did not include these items in the previous list, since in their synthetic forms they can be kitniot-free, and I haven't found specific information from any certifying agencies saying that kitniot-derived versions are Kosher for Passover. I would, however, recommend that people who are highly sensitive to corn use cautioun with these ingredients also if they are certified by agencies that allow "changed" kintiot.
The Star-K website states: "The Star-K policy is not to use Kitniyos Shenishtanu. This is why you will not see sodium erythrobate or sodium ascorbate ingredients, found in almost all deli meats, on Star-K approved kosher for Passover processed meats."
Scroll-K includes derivatives such as citric acid, xanthan gum and many articifical sweeteners in their official list of "Kitniyos By Any Other Name" in the 2006 Kosher for Pesach directory.
However, even a product certified Kosher for Passover by the most stringent agency may not be guaranteed corn-free.
An important thing for the corn-intolerant to know is that the prohibition on kitniot only applies to foods that are eaten. It does not apply to many medications, most pills that are swallowed without being chewed, or to non-food products such as soap and cosmetics. There are also certain exceptions made for the very young, elderly or ill.
The bottom line is that, since the kitniot rules are only a minhag (custom) as opposed to a law, there is much more leniency with the use of kitniot than with chametz (grains that can grow yeast).
While it is easier to find corn-free products among the Kosher for Passover selection, we still have to be careful. People with contact allergies should be especially careful not to assume that Kosher for Passover non-food products such as soap would be corn-free, since non-food items need only be chametz-free and can contain kitnios without creating a problem in their kosher status.
For more information about the rules regarding kitniot and chametz, and why these are important at Passover time, please see my more detailed posts at the Purple Puzzle Place:
What is Kosher for Passover, and why Kitniot-Free?
Kitniot or Not?