Cranberry Forte 50,000mg 90 Capsules

Cranberry is one of the few herbal products with a large, consistent body of evidence, but the pack often tells you the least about what you're buying. These are the questions our naturopaths ask in store.

A good fit if

• You get urinary infections again and again and want something preventive
• You're buying for a child, where the combined trial benefit was largest
• You'll look for a listed proanthocyanidin figure rather than a fresh-fruit-equivalent number
• You want to prevent infections rather than treat one, and you understand the difference

Check with us first if

• You take warfarin. The evidence on an interaction is genuinely mixed.
• You take tacrolimus or another transplant medicine. Lower than intended medicine levels have been reported.
• You have diabetes and are considering juice, because of the sugar.
• You're buying for someone in residential care. The combined trials showed no benefit in that group.
• You get infections often and haven't had them investigated.

• Whole cranberry fruit powder capsule. Best known for: The dried whole fruit: the PACs plus everything else. Absorption: Studied at around 500 mg a day in the whole-fruit trials. Typical use: A middle option between juice and a concentrated extract.
• High-PAC standardised extract. Best known for: Concentrated for proanthocyanidins (PACs) in particular. Absorption: Studied at around 240 mg a day in the standardised trials. Typical use: The form where you can actually check the active dose.
• Juice. Best known for: PACs plus a lot of fluid, and the fluid matters too. Absorption: 500 mL a day of 27% juice was used over eight weeks. Typical use: Watch the sugar in sweetened versions.
• Capsule labelled by fresh-fruit equivalent. Best known for: The 25,000 mg to 70,000 mg packs you see all over Australian shelves. Absorption: The equivalent figure tells you nothing about PAC content. Typical use: Look for a stated PAC figure instead.
• Cranberry with probiotics. Best known for: Adds Lactobacillus strains that have their own urinary evidence. Absorption: Two actives rather than one. Typical use: Worth considering if problems keep coming back.

Reference values. There's no recommended intake for cranberry, because it's a fruit rather than a nutrient.

Typical supplemental range. Australian packs are usually once-daily capsules labelled 25,000 mg to 70,000 mg of fresh fruit equivalent. That number tells you how concentrated the extract is, not how much active ingredient it has. The figure that matches the trial benefit is proanthocyanidins, at 36 mg a day or more, and it's rarely listed. Trials used roughly 500 mg a day of whole fruit powder, 240 mg a day of a high-PAC extract, or 500 mL a day of 27% juice.

Upper level. None is set, and Australia's permitted ingredients list (Schedule 1) has no dose cap for Vaccinium macrocarpon (item 5118) or Vaccinium oxycoccus (5121). The practical limit is the oxalate it adds rather than any toxicity, which is why a history of kidney stones changes the answer.

Worth knowing. If a pack doesn't list proanthocyanidins, you can't compare it on the thing that matters. What you need depends on your age, diet and health, so talk to one of our naturopaths.

Food first, where the diet allows it.

• Cranberry juice: trials used 500 mL a day of 27% juice
• Fresh or frozen cranberries: very tart; rarely eaten plain in Australia
• Dried sweetened cranberries: common in muesli and bars; sugar is usually added

If any of these sound like you, talk to one of our naturopaths or your doctor before you start.

• You have had calcium oxalate kidney stones. Cranberry increased the oxalate passed in urine over 24 hours, so don't take it.
• You take warfarin. The evidence genuinely conflicts, and NCCIH describes it that way rather than as settled either way.
• You take tacrolimus or other transplant medicines. Taking them together has led to blood levels of the medicine that were too low to work.
• You have a urinary tract infection now. Cranberry is for prevention, and an infection needs a medical check.
• People living in care facilities. The pooled result showed no effect in this group.
• You have diabetes or are managing your blood sugar. Juice carries a real sugar load, especially sweetened versions.
• If you take prescription medicines, check with your doctor, pharmacist or our naturopaths before you start.