Functional Foods
Foods studied for health: what research shows, what labels mean, and what is still unproven.
Choose a place to start
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Understanding Functional Foods
What the term means, how functional foods differ from supplements and "superfoods", the A to Z directory and how to read food health claims.
6 guides
- Explore Functional Foods
- What Are Functional Foods?
- Functional Foods vs Supplements vs Medicine: How They Differ
- Superfoods: What the Word Means and Does Not Mean
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Fermented Foods & Drinks
Yogurt, kefir, kimchi, sauerkraut, kombucha, miso, tempeh and natto. Live cultures depend on the product; fermented does not mean probiotic.
15 guides
See the 15 pages -
Fiber-Rich & Prebiotic Foods
Whole grains, legumes and seeds. The best-supported effects are for beta-glucan and cholesterol.
9 guides
See the 9 pages -
Nuts, Seeds & Unsaturated Fats
Walnuts, almonds, pistachios, seeds, avocado and olive oil. Studied by swapping them for other foods, not adding them on top.
8 guides
See the 8 pages -
Fruits & Vegetables
Berries, pomegranate, citrus, tomatoes, crucifers, leafy greens, beets and more. Most disease evidence is observational.
14 guides
See the 14 pages -
Fish, Soy & Other Protein Foods
Protein foods. Fish as food is kept apart from fish-oil supplements.
4 guides
See the 4 pages -
Tea, Coffee, Cocoa & Other Drinks
Black tea, matcha, coffee, dark chocolate, coconut water, juices and plant milks: common drinks with large evidence bases.
7 guides
- Black Tea
- Coffee
- Matcha and Green Tea as Drinks: Research, Caffeine and Liver Cautions
- Dark Chocolate and Cocoa as Food: Research, Sugar and Metals
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Spices & Culinary Seasonings as Food
Turmeric, ginger, cinnamon, garlic, black pepper and others as foods. Herb and extract evidence is in Herbs & Botanicals.
5 guides
- Turmeric as a Food: Spice vs Supplement
- Ginger as a Food: Fresh, Dried and in Cooking
- Cinnamon as a Food: Cassia vs Ceylon and Coumarin
- Black Pepper, Cayenne and Capsaicin Foods
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Fortified Foods
Foods with nutrients added. Different from supplements and from naturally rich foods.
3 guides
- Fortified Foods
- Fortified Plant Milks and Cereals: What Is Added and What Labels Show
- Fortification Policy: Folic Acid, Iodized Salt and Vitamin D
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Nutrients & Compounds in Foods
Fiber, beta-glucan, resistant starch, polyphenols, nitrate, omega-3, plant sterols, isoflavones and others: what each does and which foods have it.
7 guides
- Nutrients & Compounds in Foods
- Beta-Glucan in Foods: Oats, Barley and Mushrooms
- Polyphenols and Flavonoids in Foods: Berries, Cocoa, Tea and Olive Oil
- Dietary Nitrate in Beets and Leafy Greens
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Functional Foods by Wellness Goal
Cholesterol, blood sugar, blood pressure, gut, brain, weight and more: which foods have what evidence.
8 guides
- Functional Foods by Wellness Goal
- Foods for Cholesterol and Heart Health: What Trials Found
- Foods and Blood Sugar: Fiber, Vinegar, Cinnamon and Others Checked
- Foods for Blood Pressure: DASH, Beets, Potassium and Hibiscus
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Preparation & Everyday Use
Fresh, frozen and canned; whole fruit versus juice; raw versus cooked; pasteurized versus unpasteurized; storage and food safety.
5 guides
- Preparation & Everyday Use
- Fresh, Frozen and Canned Produce: Nutrient Differences
- Soaking, Sprouting and Cooking Beans and Grains: Safety Points
- Pasteurized vs Unpasteurized Foods: Juice, Cheese, Milk and Ferments
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Quality & Labels
Reading the nutrition label, added sugar, sodium, fiber claims, live cultures, organic and health claims on packages.
5 guides
- Quality & Labels
- Added Sugars, Sodium and Saturated Fat on Labels
- Fiber and "Whole Grain" Claims on Packages
- Probiotic Claims on Food Labels
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Safety & Individual Considerations
Medicine interactions, pregnancy, allergy, histamine and tyramine, kidney and gout questions, and when to ask a professional.
8 guides
- Safety & Individual Considerations
- Foods and Medicine Interactions: Vitamin K, Grapefruit, Tyramine and Others
- Food Allergy Basics and Emergency Signs
- Foods, Kidney Disease, Potassium and Oxalates
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Claim Checks
"Superfood", "detox", "anti-inflammatory" and other food claims, checked against the sources.
4 guides
- Claim Checks
- Detox Foods and Juice Cleanse Claims Checked
- Gut Health Food Claims Checked: "Feed Your Microbiome"
- Seed Oils and Inflammation Claims Checked
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Science, History & Policy
How nutrition studies work, observational versus trials, dietary guidelines and regulation of food claims.
5 guides
- Research & Evidence
- Observational Studies vs Trials in Nutrition: Why Food Evidence Is Hard
- Human Trials and Meta-Analyses of Foods: What Exists and Limits
- Research by Food: Evidence Snapshot Table
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Comparisons
Yogurt vs kefir, kimchi vs sauerkraut, flaxseed vs chia, whole fruit vs juice and more. No rankings.
6 guides
See the 6 pages -
Glossary & Quick Reference
Terms, a food table, frequently asked questions and a safety quick reference.
4 guides
- Glossary of Functional Food Terms
- Functional Foods at a Glance: Evidence and Safety Table
- Functional Foods: Frequently Asked Questions
- Food Safety Quick Reference: Warning Signs and Whom to Call
Search foods and A to Z list
123 pages, A to Z
A
B
- BarleyFiber-Rich & Prebiotic Foods
- Beetroot & Beet JuiceFruits & Vegetables
- Berries Beyond Blueberries: Strawberries, Raspberries and BlackberriesFruits & Vegetables
- Beta-Glucan in Foods: Oats, Barley and MushroomsNutrients & Compounds in Foods
- Black Pepper, Cayenne and Capsaicin FoodsSpices & Culinary Seasonings as Food
- Black TeaTea, Coffee, Cocoa & Other Drinks
- BlueberriesFruits & Vegetables
- Bone Broth as Food: Claims CheckedFish, Soy & Other Protein Foods
- Broccoli & Cruciferous VegetablesFruits & Vegetables
C
- Caffeine in Foods and Drinks: What Official Limits SayTea, Coffee, Cocoa & Other Drinks
- Chia SeedsFiber-Rich & Prebiotic Foods
- Cinnamon as a Food: Cassia vs Ceylon and CoumarinSpices & Culinary Seasonings as Food
- Citrus Fruits & Orange JuiceFruits & Vegetables
- Claim ChecksClaim Checks
- CoffeeTea, Coffee, Cocoa & Other Drinks
- ComparisonsComparisons
- Cranberries and Urinary Tract Infections: What Cochrane FoundFruits & Vegetables
D
- Dark Chocolate and Cocoa as Food: Research, Sugar and MetalsTea, Coffee, Cocoa & Other Drinks
- Detox Foods and Juice Cleanse Claims CheckedClaim Checks
- Dietary Nitrate in Beets and Leafy GreensNutrients & Compounds in Foods
- Dietary Patterns Studied: Mediterranean, DASH and OthersUnderstanding Functional Foods
E
F
- Fermented Foods and Gut Health: What Trials FoundFermented Foods & Drinks
- Fermented Foods Safety and Home-Fermentation RisksFermented Foods & Drinks
- Fermented Foods vs Probiotic SupplementsComparisons
- Fiber and "Whole Grain" Claims on PackagesQuality & Labels
- Fiber: Official Intake Amounts, Food Sources and Side EffectsFiber-Rich & Prebiotic Foods
- Fish and Mercury: What Official Advice SaysFish, Soy & Other Protein Foods
- FlaxseedFiber-Rich & Prebiotic Foods
- Flaxseed vs Chia SeedsComparisons
- Food Allergy Basics and Emergency SignsSafety & Individual Considerations
- Food Safety Basics: Storage, Leftovers and Cross-ContaminationPreparation & Everyday Use
- Food Safety Quick Reference: Warning Signs and Whom to CallGlossary & Quick Reference
- Foods and Blood Sugar: Fiber, Vinegar, Cinnamon and Others CheckedFunctional Foods by Wellness Goal
- Foods and Medicine Interactions: Vitamin K, Grapefruit, Tyramine and OthersSafety & Individual Considerations
- Foods for Babies and Toddlers: Choking, Honey and Allergen IntroductionSafety & Individual Considerations
- Foods for Blood Pressure: DASH, Beets, Potassium and HibiscusFunctional Foods by Wellness Goal
- Foods for Brain Health and Memory: What the Research ShowsFunctional Foods by Wellness Goal
- Foods for Cholesterol and Heart Health: What Trials FoundFunctional Foods by Wellness Goal
- Foods for Gut Health and BloatingFunctional Foods by Wellness Goal
- Foods in Pregnancy: What Official Bodies Advise Eating and AvoidingFunctional Foods by Wellness Goal
- Foods, Kidney Disease, Potassium and OxalatesSafety & Individual Considerations
- Fortification Policy: Folic Acid, Iodized Salt and Vitamin DFortified Foods
- Fortified FoodsFortified Foods
- Fortified Plant Milks and Cereals: What Is Added and What Labels ShowFortified Foods
- Fresh, Frozen and Canned Produce: Nutrient DifferencesPreparation & Everyday Use
- Fruit Juice vs Whole Fruit: What Research ShowsFruits & Vegetables
- Functional Foods at a Glance: Evidence and Safety TableGlossary & Quick Reference
- Functional Foods by Wellness GoalFunctional Foods by Wellness Goal
- Functional Foods vs Supplements vs Medicine: How They DifferUnderstanding Functional Foods
- Functional Foods: Frequently Asked QuestionsGlossary & Quick Reference
G
- Ginger as a Food: Fresh, Dried and in CookingSpices & Culinary Seasonings as Food
- Glossary of Functional Food TermsGlossary & Quick Reference
- Greek Yogurt vs Regular YogurtComparisons
- Green, Black, White and Oolong Tea: What DiffersTea, Coffee, Cocoa & Other Drinks
- Gut Health Food Claims Checked: "Feed Your Microbiome"Claim Checks
H
- Heavy Metals and Contaminants in Foods: Rice, Fish, Cocoa and Baby FoodsSafety & Individual Considerations
- Histamine, Tyramine and Fermented Foods: Who Needs to Be CarefulFermented Foods & Drinks
- How to Compare Packaged Functional Foods: A Checklist With No RankingsQuality & Labels
- How to Read Nutrition Research HeadlinesUnderstanding Functional Foods
- Human Trials and Meta-Analyses of Foods: What Exists and LimitsScience, History & Policy
K
L
M
N
O
- OatsFiber-Rich & Prebiotic Foods
- Observational Studies vs Trials in Nutrition: Why Food Evidence Is HardScience, History & Policy
- Oily FishFish, Soy & Other Protein Foods
- Omega-3 Fatty Acids in Foods: Fish, Walnuts, Flax and ChiaNutrients & Compounds in Foods
- Onions, Garlic and Allium Vegetables as FoodFruits & Vegetables
- Other Nuts: Pecans, Cashews, Brazil Nuts and MacadamiasNuts, Seeds & Unsaturated Fats
P
- Pasteurized vs Unpasteurized Foods: Juice, Cheese, Milk and FermentsPreparation & Everyday Use
- Pickles: Fermented vs Vinegar Pickles and What Counts as ProbioticFermented Foods & Drinks
- PistachiosNuts, Seeds & Unsaturated Fats
- Plant Milks: Oat, Almond, Soy and OthersTea, Coffee, Cocoa & Other Drinks
- Plant Sterols and Stanols in Foods and Fortified SpreadsNutrients & Compounds in Foods
- Polyphenols and Flavonoids in Foods: Berries, Cocoa, Tea and Olive OilNutrients & Compounds in Foods
- PomegranateFruits & Vegetables
- Prebiotic Foods: Inulin, Onions, Garlic, Chicory and MoreFiber-Rich & Prebiotic Foods
- Preparation & Everyday UsePreparation & Everyday Use
- Probiotic Claims on Food LabelsQuality & Labels
- Probiotics, Prebiotics & Fermented FoodsFermented Foods & Drinks
- Pumpkin SeedsNuts, Seeds & Unsaturated Fats
Q
R
- Raw Sprouts, Raw Milk and Undercooked Foods: Risks for Higher-Risk GroupsSafety & Individual Considerations
- Research & EvidenceScience, History & Policy
- Research by Food: Evidence Snapshot TableScience, History & Policy
- Resistant Starch Foods: Cooked-and-Cooled Starches, Green Bananas and BeansFiber-Rich & Prebiotic Foods
S
- Safety & Individual ConsiderationsSafety & Individual Considerations
- Saffron, Cloves and Other Whole Spices as FoodSpices & Culinary Seasonings as Food
- SauerkrautFermented Foods & Drinks
- Seed Oils and Inflammation Claims CheckedClaim Checks
- Soaking, Sprouting and Cooking Beans and Grains: Safety PointsPreparation & Everyday Use
- Sourdough Bread: Claims CheckedFermented Foods & Drinks
- Soy FoodsFish, Soy & Other Protein Foods
- Sulforaphane and Glucosinolates in Cruciferous VegetablesNutrients & Compounds in Foods
- Superfoods: What the Word Means and Does Not MeanUnderstanding Functional Foods
- Sweet Potatoes, Carrots and Orange VegetablesFruits & Vegetables
T
- Tart Cherries and Cherry Juice: Research on Sleep, Gout and ExerciseFruits & Vegetables
- TempehFermented Foods & Drinks
- TomatoesFruits & Vegetables
- Traditional Diets and Food as Medicine in Different CulturesScience, History & Policy
- Turmeric as a Food: Spice vs SupplementSpices & Culinary Seasonings as Food
W
Y
Safety first with foods
- Food allergy can be an emergency. Call 911 for trouble breathing or swelling of the face or throat.
- Some foods affect medicines: grapefruit, vitamin K foods with warfarin, tyramine with some antidepressants, and potassium-rich foods with some blood pressure or kidney conditions.
- Pregnancy, infants, older adults and people with weak immune systems have extra food-safety needs, such as avoiding raw sprouts and unpasteurized products.
- Tell your clinician or pharmacist about big changes in what you eat if you take medicines. In the US, Poison Help is 1-800-222-1222; call 911 for collapse, seizure, trouble breathing or swelling of the face or throat.
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 .
Education, not medical advice. This section is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe.
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