Colored foods can be very attractive to kids, however artificial dyes are completely out of question for my family! The good news is that there are plenty of fun (and healthy) options available. Here are a few ideas from Sayward Rebhal, Networkx:
Pink and Red
You can use any number of options, but for a ton of color with almost no flavor, beets are your best bet. Use the juice from the canned kind, or make your own by either boiling or juicing the raw vegetable. Learn exactly how to make frosting colored by beets from Joy the Baker.
Alternately, you can also use any red fruit, like raspberries or pomegranate. Just know that these may change the flavor - which can be a great thing! To procure your dye, pulverize the berries in a food processor or blender, then strain out the colored liquid using a mesh sieve or cheesecloth.
Carrots are your best bet for achieving a perfectly peachy tint. Citrus may seem promising, but it doesn't lend much color. Stick to carrots and you're sure to be pleased. Just juice them (or buy fresh carrot juice), and don't worry about the flavor. Carrots are naturally sweet! Itsy Bitsy Foodies offered a super tutorial on how to make food coloring from carrots.
Both saffron flowers and turmeric powder will create that sunny, summery hue. These are each intensely-colored spices, so a little goes a long way. Still, be careful, start with very small amounts, and taste as you add. I recommend these two recipes for yellow food coloring: Quick and Easy Cheap and Healthy published an awesome recipe for making icing colored with saffron. Nouveau Raw published a delicious recipe for raw vegan frosting colored with turmeric.
Are you forever trying to find ways of getting greens into your kids? (Or into yourself?!) Well, how about . . . spinach in the frosting! That's right, a little spinach will work like a charm, and doesn't impart any flavor at all (PROMISE!).
You can use juice, or you can even use the whole leaves. I recommend that you try The Edible Perspective's recipe for Green Monster Wipped Green Frosting, which includes two cups of spinach leaves.
Another option for that emerald tone involves a "health food" supplement called chlorophyll. Liquid chlorophyll is available in most alternative markets (co-ops, Whole Foods) and is quite inexpensive. Besides it's purported health benefits, it's a great option for natural food coloring.
Blue and Purple
And finally, the tricky twosome. Blues and purples can be a bit harder, but they certainly are possible. Blueberries and blackberries can be used in the same process as described above (for other berries, under "Pink and Red"). But your real best bet is a totally unexpected vegetable: cabbage!
That's right! Red cabbage can be used to make both purple and blue food coloring. For the former, cut and boil the cabbage until the water is very dark and concentrated. This will give you a pretty purple dye.
For the latter, slowly stir in baking soda, a bit at a time. It will react with the cabbage juice and produce a perfectly pretty blue hue.
Source: Networx, Shine