Functional Foods
Functional foods are foods studied for effects beyond basic nutrition: oats and cholesterol, yogurt and the gut, nuts and the heart. This section keeps what trials show apart from what large observational studies suggest, and says plainly where proper evidence was not found.
Foods are not supplements. A result for a whole food does not carry over to a capsule, a juice or a fortified product, and "superfood" is a marketing word, not a scientific category.
Safety & Individual Considerations
- Food can interact with medicines. Grapefruit affects some statins and blood pressure drugs; leafy greens and natto affect warfarin; aged and fermented foods matter with MAOI antidepressants.
- In pregnancy, unpasteurized dairy, raw sprouts and some fish carry specific risks. Fermented does not mean pasteurized.
- A food that helps in a study does not treat a condition. Do not stop a prescribed medicine to try a food.
- Severe allergic reaction (swelling, trouble breathing): call 911. In the US, Poison Control is 1-800-222-1222.
Explore functional foods
-
Fermented Foods & Drinks
Foods made through microbial growth.
See all foods -
Fiber-Rich & Prebiotic Foods
Whole grains, legumes and seeds.
See all foods -
Nuts, Seeds & Unsaturated Fats
Nuts, seeds and avocado.
See all foods -
Fruits & Vegetables
Whole produce and juices.
- Blueberries
- Pomegranate
- Citrus Fruits & Orange Juice
- Tomatoes
- Broccoli & Cruciferous Vegetables
- Leafy Greens
- Beetroot & Beet Juice
-
Fish & Soy Foods
Fish and soy foods.
See all foods -
Tea & Coffee
Black tea and coffee.
See all foods -
Fortified Foods
Foods with nutrients added.
See all foods
What Are Functional Foods?
Definitions, and how functional foods differ from supplements and "superfoods".
Probiotics, Prebiotics & Fermented Foods
The ISAPP definitions: probiotic, prebiotic, synbiotic, postbiotic and fermented food.
Nutrients & Compounds in Foods
Fiber, beta-glucan, polyphenols, omega-3, sterols, isoflavones and nitrate.
Functional Foods by Wellness Goal
Which foods have evidence for cholesterol, blood sugar, gut health and more.
Preparation & Everyday Use
Fresh vs frozen, whole vs juiced, pasteurized vs unpasteurized.
Quality & Labels
Nutrition label, added sugar, sodium, fiber claims and live cultures.
Comparisons
Yogurt vs kefir, kimchi vs sauerkraut, flaxseed vs chia and more.
Claim Checks
Superfood and detox food claims, checked.
Research & Evidence
How much research each food has.
Featured guides
Our first food guides are being written and reviewed. We publish a guide only when it is sourced and ready.
Frequently asked questions
What are functional foods?
Foods studied for health effects beyond basic nutrition; there is no single legal definition. [1] See What are functional foods.
Is a fermented food a probiotic?
Not automatically. [2] See Probiotics, prebiotics and fermented foods.
Can food treat a condition?
Foods lowered markers such as LDL cholesterol modestly in studies; they do not replace treatment. See Safety.
Which foods interact with medicines?
Grapefruit, vitamin K foods and fermented foods can matter. [3][4][5]
References
- NutraIngredients. FDA still reviewing functional food regulatory requirements. 2009 trade-press summary that FDA has no regulatory definition of functional foods; check for newer FDA guidance.
- Marco ML et al. The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on fermented foods. Nat Rev Gastroenterol Hepatol 2021. PMID 33398112.
- U.S. Food and Drug Administration. Grapefruit Juice and Some Drugs Don't Mix.
- Cedars-Sinai. For Warfarin: Eating a Consistent Vitamin K Diet. Patient education page; ask your anticoagulation clinic for your own plan.
- Mayo Clinic. MAOIs and diet: Is it necessary to restrict tyramine?.
Content last updated . This section has not been medically reviewed.