Some years ago members of my congregation visited their home congregation over the Christmas holiday. As is usual, they brought me back a bulletin. It should be said that this was an ELCA congregation and that the Pastor was female and well along in a pregnancy -- a fact no incidental to this discussion. In the instructions for the distribution of Holy Communion, those communing were told that all the individual cups contained wine except "for those closest to Pastor's stomach" (a pregnancy reference here) which contained grape juice "for those unable to drink or who do not like wine." A year or so ago I read through a bulletin from an LCMS congregation that a member had visited. It too had instructions for the distribution offering non-gluten hosts for those with gluten allergies and non-alcoholic wine for those unable or unwilling to drink wine.
I am suspicious of this growing practice to alter the elements in the Lord's Supper to fit either the health needs or tastes of communicants. Perhaps the day will come when we will have a special distribution point to care for those with unusual tastes or physical needs for the elements of the Lord's Supper. Maybe the day will come when we will have substitutes that we can all agree are better than the ones which our Lord used when, on the night when He was betrayed, He took bread. . .
I believe we should leave well enough alone. The Church has historically taught that the bread must be made of only wheat and water with "sufficient gluten to attain the confection of bread." In the same way the Church has historically taught that the wine is the fruit of the vine (grape) and whose fermentation is not corrupted or prevented. We know from the Corinthian situation that the Lord's Supper had been abused so that the people there had drunk freely enough of the cup of the Lord so that they became drunk and they communed to their harm and not their good by such callous disregard for the Lord's Supper.
Why not leave it at the Lord's intention and institution? Bread (whether leavened or not but of wheat flour) and wine (historically of a rather high alcohol content but without regard to color). Wine was used by the Church from the very beginning for the Eucharist. Grape juice did not even become a real option until Mr. Welch came along and invented a way to pasteurize grape juice so that it would keep long enough to be used. Of course the Temperance movement was one of the first modern attempts to bend theology and praxis to fit social whims. And this is what gave birth to individual cups... but leave that discussion for another time.
So what do we do with people who desire to commune but are prevented either from allergy or medical condition from receiving either gluten or alcohol?
I encourage worshipers to recall that the total Christ is present in either element, the so-called Doctrine of Concomitance. It is sufficient for you to receive either bread or cup alone, when you cannot, for medical reasons, receive both. That is, when you receive the bread or the cup you receive the full Communion in the Lord Jesus Christ and what you receive is not diminished by the lack of either element. This solution seems to resolve the issue with more compassion and less embarrassment for all than to provide alternate food (such as non-gluten bread, or grape juice) in alternate containers (such as individual glasses). Others suggest what the Roman Church offers to priests unable to drink alcohol -- intinction that allows the host to touch the wine in minimal form. Certainly this intinction is an acceptable substitute but not one with which Lutheranism has had a great deal of history.
Since the time of year when Jesus instituted the Lord's Supper was far removed from the time of grape harvest, this would have prevented any fresh, unfermented grape juice from being present. To go beyond what Jesus did throws the whole nature of the Sacrament into uncertainty (I cannot say whether Christ is present in grape juice or non-wheat bread but neither do we have any assurance that He is). Why stop with non-wheat bread or grape juice? Why not substitute some other element entirely? No, I say let it be sufficient for us to do what Christ did. Period. (At the very least I hope we can forgo the cutesy ways of describing where the element of choice can be found...)