Cranberries

Cranberries are small red berries that often taste tart. If you want to know where they come from and what kinds there are, it's not hard. You can imagine cranberries as little red pearls that like to grow in wet soils or bogs – it looks a bit like a wet lawn carpet.

Origin and growing regions
The most well-known cranberries originally come from North America. The major growing areas there are:

Today cranberries are also cultivated elsewhere:

Different varieties
There are two main groups of cranberries that are easy to distinguish:

Within these groups there are many cultivars — it's like with apples (e.g. Granny Smith or Gala). Some varieties are more acidic, others somewhat sweeter or have firmer flesh.

Available forms in stores
You can get cranberries not only fresh. Here are the usual forms in which they are sold:

In summary: if you can't find fresh cranberries, frozen, dried or as juice are good alternatives. Fresh ones are mainly available in autumn, while processed forms are available year-round. That way you can enjoy the bright red berries almost always in some form.

Cranberries are small red-colored berries of the genus Vaccinium, most commonly represented by Vaccinium macrocarpon (American cranberry) and Vaccinium oxycoccos (bog cranberry). They prefer to grow in acidic, wet soils and are harvested by both dry and wet methods. Wet harvest often takes place in flooded fields, where the berries float to the surface due to their air pockets and can thus be collected mechanically.

The chemical composition of cranberries is complex and is characterised by a high water content and secondary plant compounds. Typical macronutrient-related values for fresh cranberries are about 46 kcal per 100 g, around 12 g of carbohydrates, dietary fiber about 4–5 g and very low amounts of fat and protein. In addition, cranberries contain moderate amounts of vitamin C and minerals such as potassium. Exact nutritional values vary by variety, ripeness and processing.

Key bioactive constituents are polyphenolic compounds, in particular:

Processing leads to characteristic changes. Heating and storage cause degradation of vitamin C and anthocyanins, while drying or concentration increases sugar content per mass. Industrial products include fruit flesh, juices, concentrates, dried (often sweetened) cranberries and freeze-dried powders. The choice of process affects both the sensory profile and the level of functional polyphenols.

Regarding health, cranberries are the subject of intensive research. Mechanistically they are attributed antioxidant effects and an ability to reduce the adhesion of certain bacterial strains (particularly uropathogenic Escherichia coli) to urinary tract cells, mediated by A‑type proanthocyanidins. Clinical trials for the prevention of urinary tract infections, however, show heterogeneous results, which is due in part to different preparations, doses and study populations. Other investigated effects include possible cardiovascular benefits, modulation of the gut microbiota and oral health, with varying strength of evidence and often a need for further research.

In terms of safety, food amounts are generally well tolerated. In highly concentrated preparations, interactions have been reported occasionally, for example with the anticoagulant warfarin, so medical advice is recommended during long-term medication. People prone to kidney stones should be aware of oxalate content and consult their treating physician if necessary.

In summary, cranberries are a water-rich fruit with low energy density and a polyphenol-rich profile that is thought to be responsible for potentially beneficial health effects. The quality of demonstrable health effects depends strongly on the type of preparation, the dose and the composition of the specific product, so claims about effectiveness should be evaluated in a differentiated way and on the basis of specific studies.