Radicchio is a leaf chicory which is occasionally known as Italian chicory. It is often grown as a leaf vegetable.
It has white veined red leaves and has a bitter and spicy taste. However it is often roasted or grilled which will mellow the taste.
So can guinea pigs eat radicchio, and if they can how much of can be eaten?
Lets take a look here at its nutritional data and find out more about it.
In particular, its acidic, fat, calcium, sugar and phosphorus content is of particular interest.
Nutritional value per 100 g (3.5 oz)
Energyt96 kJ (23 kcal)
Carbohydratest4.48 g
– Sugarst0.6 g
– Dietary fibert0.9 g
Fatt0.25 g
Proteint1.43 g
– lutein and zeaxanthint8832 μg
Thiamine (vit. B1)t0.016 mg (1%)
Riboflavin (vit. B2)t0.028 mg (2%)
Niacin (vit. B3)t0.255 mg (2%)
Pantothenic acid (B5)t0.269 mg (5%)
Vitamin B6t0.057 mg (4%)
Folate (vit. B9)t60 μg (15%)
Vitamin Ct8 mg (10%)
Vitamin Et2.26 mg (15%)
Vitamin Kt255.2 μg (243%)
Calciumt19 mg (2%)
Iront0.57 mg (4%)
Magnesiumt13 mg (4%)
Manganeset0.138 mg (7%)
Phosphorust40 mg (6%)
Potassiumt302 mg (6%)
Sodiumt22 mg (1%)

(source: Wikipedia)
As you can see radicchio contains a hint of calcium, a little phosphorus, and a little acidic, it also contains a hint of fat and sugar.
From the info above guinea pigs eat raddichio two to three times a week but it doesn’t contain a great deal of vitamin c