It’s a simple enough question, but the answer can be elusive, especially because it depends on what kind of cranberries we’re talking about: fresh, juiced or dried.
If we’re talking about 100g of ordinary, raw cranberries, the carbohydrate figures according to wikipedia are as follows: dietary fibre = 4.6g; total sugars = 4.04. These figures might confuse some of us however, because as low carb dieters we are advised to subtract dietary fiber from total carbohydrates to calculate “net carbs” which is the figure we really care about (dietary fiber is a carbohydrate, but it is not digested so doesn’t contribute to raising blood sugar levels).
As wikipedia lists only total sugars and not total carbohydrates, its necessary to check another reputable source to see if they list total carbs. The calorie counter at about.com gives us the following numbers for 1 cup (95g) of cranberries: dietary fiber = 4.4g; sugars = 3.8g; total carbohydrates = 11.6g. Subtracting the fiber from the total gives us 7.2g net carbs, which is low enough for us to conclude that cranberries are a low carb fruit. So far so good, except that we hardly ever eat cranberries raw, we are more likely to drink their juice or eat them dried.
If we’re talking about 95g of cranberry juice, these figures from the National Agricultural Library should be interesting: dietary fiber = 0.1g; sugars = 11.49g; total carbohydrates = 11.59g, giving us net carbs of 11.49g (11.59 – 0.1). In other words, gram for gram, cranberry juice contains 1.5 times as many net carbs as raw cranberries. But how often would we drink just 95g of juice?
A typical cup holds 253g of liquid. Using a cup as our new unit of measurement gives us 7.2g net carbs for raw cranberries and a whopping 30.57g net carbs for cranberry juice! Although fundamentally cranberries are a low carb fruit, when you consider how many cranberries must be used to produce a single glass of juice, and the fact that most of the fiber is removed, its easy to see how concentrated the sugar content would be.
Now if that’s not bad enough, most cranberry juice has extra sugar added to it because the pure stuff is simply too sour for most people’s tastes. So unless it’s a specially processed cranberry juice made with artificial sweetener, you’re probably best to avoid cranberry juice on a low carb diet.
Finally, let’s consider dried cranberries, popularly known as “craisins”. Unfortunately, most commercially available craisins are loaded with sugar for the same reason cranberry juices are – plain dried cranberries are too sour for most people. The exact net carb count for a cup of dried craisins would depend on the brand because each producer has its own production process, but suffice it to say that unless they are artificially sweetened, dried cranberries are not low carb fruit.
If you’re lucky enough to get a hold of dried unsweetened cranberries, the net carb count on a gram for gram basis will still be higher than for fresh ones simply because they are smaller, so you can fit more of them into 95g than you can the raw fruit.
So are cranberries a low carb fruit? In theory yes, but in practice, the answer is often no.