Carbohydrate counting is very important in a diabetic diet where one needs to maintain their blood sugar levels. Most of these patients are asked to avoid potato and beetroot as it is assumed that these can increase the carbohydrate intake in the diet.
Firstly let me tell you what vegetable come under roots and tubers?
Root vegetables are carrots,parsnip,radish,turnip,beetroot etc and tuber vegetables are potato, sweet potato, tapioca, yam etc. Onions, garlic and leeks come under bulbs.
From the nutritional point of view, roots and bulbs have lesser carbohydrate or sugar content compared to tubers. For 100 grams, carbohydrate content of roots such as carrots contain 10.6g, beetroot contain 8.8g,radish 6.8g, turnip 6.2g but except for parsnip which contains 23g of carbohydrates.
All Tubers contain carbohydrates ranging from 20-30 grams.
Bulbs like onions contain 11 grams.
So it is quite safe to include roots and bulbs in your diet rather than tubers. Tubers too can be had occasionally on adjusting the carbohydrate content for the day.