Cranberry

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, PACs plus everything else. Absorption: Studied 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 specifically for proanthocyanidins. Absorption: Studied 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 large volume 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 that dominate Australian shelves. Absorption: The equivalent number says nothing about PAC content. Typical use: Look for a declared PAC figure instead.
• Cranberry with probiotics. Best known for: Adds Lactobacillus strains with their own urinary evidence. Absorption: Two actives rather than one. Typical use: Worth considering for recurrent problems.

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

This list is the part of the page we will not shorten. If any of it applies to you, talk to one of our naturopaths or your doctor before starting.

• History of calcium oxalate kidney stones. Cranberry increased 24-hour urinary oxalate excretion; avoid on that basis.
• Warfarin. The evidence is genuinely conflicting, with NCCIH describing it as such rather than settled either way.
• Tacrolimus and other transplant medicines. Concurrent use has resulted in subtherapeutic serum levels.
• Active urinary tract infection. Cranberry is a prevention product; an infection needs medical assessment.
• Institutionalised and residential care populations. The pooled result was null in this group.
• Diabetes and blood sugar management. Juice carries a real sugar load, particularly sweetened versions.
• If you take prescription medicines, check with your doctor, pharmacist or our naturopaths before starting.