- Flavonoids Linus Pauling Institute
- Jepson RG et al, 2012, Cranberries for preventing urinary tract infections Cochrane
- Howell AB, 2013, Updated systematic review suggests that cranberry juice is not effective at preventing urinary tract infection Evidence-Based Nursing
- Wang CH et al, 2012, Cranberry-containing products for prevention of urinary tract infections in susceptible populations: a systematic review and meta-analysis of randomized controlled trials PubMed
- Hisano M et al, 2012, Cranberries and lower urinary tract infection prevention PubMed Central
- Stapleton AE, 2013, Systematic review with meta-analysis: Cranberry-containing products are associated with a protective effect against urinary tract infections PubMed Central
- Pycnogenol uses, side effects MedlinePlus
- Schoonees A et al, 2012, Use of the antioxidant supplement Pycnogenol® to treat a variety of chronic disorders Cochrane
- Fine AM, 2000, Oligomeric Proanthocyanidin Complexes: History, Structure, and Phytopharmaceutical Applications Alternative Medicine Review
What are proanthocyanidins?
Examples of proanthocyanidins: procyanidins, and prodelphinidins.
Foods High in Proanthocyanidins
- FRUITS: cranberries and other berries, apples, red grapes (seeds and skin)
- Dark chocolate, cocoa
- Red wine
- Reference: 
Proanthocyanidins from Cranberry Products
There is INSUFFICIENT EVIDENCE about the effectiveness of cranberries, cranberry juice or cranberry extract supplements in the prevention of bladder and other urinary tract infections (UTIs) [2,3,4,5,6].
Oligomeric Proanthocyanidin Complexes (OPCs)
Oligomeric proanthocianidins are flavonoids naturally occurring in pine bark, grape seed and skin extracts, peanut skin, apples and cocoa .
Maritime Pine Bark Extract Pycnogenol
Pycnogenol is an oligomeric proanthocyanidin extracted from a maritime pine bark.
There is INSUFFICIENT EVIDENCE [7,8] about the effectiveness of pycnogenol in the prevention or treatment of allergy, asthma, attention deficit hyperactivity disorder (ADHD), coronary artery disease, deep vein thrombosis, dental plaques, diabetes and its complications, erectile dysfunction, heart disease, heart failure, hemorrhoids, high blood pressure, high cholesterol, hot flashes in menopausal women, leg cramps, leg swelling (edema), menstrual problems, migraine, muscle soreness, osteoarthritis, pelvic pain in women, ringing in the ears (tinnitus), skin aging, stroke, systemic lupus erythematosus (SLE) or varicose veins, or in improving athletic endurance.
Pycnogenol Safety: Side Effects, Toxicity
Pycnogenol supplements are POSSIBLY SAFE for most adults and children when taken by mouth in recommended doses for up to 1 year .
Side effects may include mouth ulcers, headache, dizziness, stomach upset .
Not enough is known about the safety of pycnogenol during pregnancy and breastfeeding, so women in these periods should avoid them .
Who else should avoid pycnogenol?
Individuals with multiple sclerosis, systemic lupus erythematosus (SLE) and rheumatoid arthritis and other autoimmune diseases should avoid pycnogenol .
Pycnogenol might enhance the blood sugar lowering effect of anti-diabetic drugs and the effect of anticoagulants .