With mounting research suggesting fructose is a major player in our chronic disease epidemics (see Why is High Fructose Corn Syrup Bad For Us? and Is Fructose a Key Player in the Rise of Chronic Health Problems?), fruit’s health-food status has diminished in some people’s minds (with “safe starches” like sweet potatoes, white potatoes, and even rice gaining a more positive reputation for their low fructose content and resistant starch). The resulting fruit-phobia has caused some of us to trade in (or severely limit) fruit in favor of other carbohydrate sources, all in the name of staying healthier.
But, the fears surrounding fruit are almost all unfounded! Far from being a fructose bomb, fruit delivers a wide spectrum of micronutrients, phytochemicals, and fiber, making it a valuable (not to mention delicious!) addition to our diets.
Fructose Is Not the Only Sugar in Fruit
Contrary to popular belief, fructose isn’t the only type of sugar in fruit—and in some cases, it’s not even the main sugar in fruit! All fruit contains a mixture of fructose, glucose, and sucrose (which metabolizes into equal parts fructose and glucose in our bodies). And, each type of fruit has a slightly (or significantly) different proportion of these sugars.
For example, papayas, grapes, and most berries are about half fructose and half glucose. Grapefruit is about a quarter fructose and a quarter glucose, with the rest coming from sucrose. And, when we calculate total metabolic fructose (the fructose in the fruit when we eat it, plus the fructose that gets cleaved from sucrose molecules during digestion), we see that most fruit yields roughly equal parts fructose and glucose. Which is great news! While fructose has to get processed in the liver, glucose is used directly by our cells for energy, and doesn’t pose the same metabolic consequences as extremely high fructose intakes (nonalcoholic fatty liver, lipogenesis, and inflammation). Combined with the fact that fresh fruit is bulky (rich in fiber and water) and takes up plenty of stomach space, it’s extremely hard to eat enough fruit to ingest the levels of fructose shown to cause harm in rodent studies and epidemiology. In other words, eating multiple servings of fruit each day is nowhere near comparable to downing fast-digesting HFCS-sweetened sodas, eating packaged foods loaded with fructose-rich sweeteners, and otherwise getting most of our fructose intake from processed foods.
Fruit Is Far From Empty Calories!
Most of us know that oranges are good source of vitamin C and bananas are loaded with potassium, but that’s just scratching the surface of fruit’s micronutrient bounty! For example, blueberries are rich in vitamin K, manganese, and copper; cantaloupes are sky-high in beta-carotene and vitamin C; pomegranates are great sources of copper, thiamin, and vitamin K; and mangoes have a decent amount of vitamin E, vitamin B6, and potassium. Each type of fruit has its own micronutrient profile, but generally speaking, fruit is a fantastic source of vitamins and a pretty good source of many minerals.
Fruit Is Full of Phytochemicals
A major reason fruit shows up as beneficial in many studies is because it’s teeming with phytochemicals (nonessential compounds that play wide-ranging roles in warding off disease and keeping us healthy). Along with giving fruit (and other plant foods!) their distinctive scents and colors, phytochemicals have the potential to protect against a variety of chronic diseases. (Check out “The Amazing World of Plant Phytochemicals” and “Polyphenols: Magic Bullet or Health Hype?” for more on these amazing compounds!) Some of the most important phytochemicals in fruit include:
- Anthocyanidins (which give some fruits a blue, purple, or deep red color) have anti-inflammatory, anti-pain, and neuroprotective effects. These are found in blueberries, cranberries, blackberries, plums, red and black grapes, cherries, and raspberries.
- Flavanones have the ability to reduce inflammation, reduce blood lipids, reduce hypertension, exert antioxidant activity, improve insulin sensitivity, and potentially protect against heart disease. And, they’re found abundantly in citrus fruit like oranges, grapefruit, tangerines, and lemons!
- Flavonols (including kaempferol, myricetin, and quercetin) can increase plasma antioxidant capacity, decrease DNA damage in lymphocytes (a type of white blood cell), interrupt the growth of certain cancers, reduce diabetes risk, protect neurons from oxidative damage, and suppress inflammation in the brain. They’re abundant in apples, cherries, and pears.
- Flavan-3-ols help maintain the elasticity of blood vessels (improving blood flow) and potentially reducing our risk of certain cancers and heart disease. They’re found in dark-skinned fruits like elderberries, cranberries, black currants, and grapes, as well as apples, bananas, peaches, pears, and strawberries.
- Tannins act as antioxidants and can reduce blood pressure, protect against harmful microbes, and improve blood lipids. They’re found in pomegranates, persimmons, and berries.
- Lycopene is famous for supporting prostate health and potentially reducing the risk of certain cancers, heart disease, osteoporosis, and diabetes. It’s found in reddish or pinkish fruits like apricots, papaya, watermelon, guava, mango, pink grapefruit, and peaches.
- Lutein and zeaxanthin support eye health (they’re highly concentrated in the retina, and help filter out damaging blue light rays) and can help prevent cataracts and age-related macular degeneration. These phytochemicals are found in kiwi fruit, oranges, grapes, honeydew melons, mangoes, peaches, nectarines, and apples.
- Stilbenes (including resveratrol, rhapontigenin, pterostilbene, and pinosylvin) are powerful antioxidants that can interfere with all stages of cancer development, as well as potentially protect against neurological diseases (including Alzheimer’s), cardiovascular disease, and diabetes. Stilbenes are highly concentrated in grape skins, cranberries, and blueberries.
One Word… Fiber!
Have I mentioned lately how awesome fiber is? No? Well, here it is: fiber is fan-freakin’-tastic! Found exclusively in the cell wall of plants, fiber provides bulk to stool (making it easier to pass) and feeds the probiotic bacteria living in our guts. (For a lot more information, check out my new e-book Fantastic Fiber) The types of fiber found in fruit can not only promote regularity, but also reduce inflammation, reduce risk of heart disease, improve blood sugar control, slow down the absorption of simple sugars (hence why fruit tends to have a low glycemic load, despite having a relatively high sugar content), bind to substances in the digestive tract (such as bile salts and toxins), protect against colorectal cancer, and help our gut critters flourish and produce beneficial short-chain fatty acids.
All that said, the optimal quantity of fruit for each of us depends on a whole host of factors: whether we’re trying to lose or gain weight; whether we have gut dysbiosis that might require limiting high FODMAP fruits (like mango, red apples, watermelon, and papaya); whether we have fructose intolerance; and whether fruit feels satiating or more like an appetite stimulant. This is serious one-size-does-not-fit-all territory, and as a result, there’s no universal prescription for the amount of fruit we should eat. But, one thing’s for sure: there’s no reason to avoid fruit on account of it being unhealthy, nutrient-poor, or worthless on the disease protection front. It’s a fantastic carbohydrate source that deserves more love than it’s been getting lately!
Aron PM & Kennedy JA. “Flavan-3-ols: nature, occurrence and biological activity.” Mol Nutr Food Res. 2008 Jan;52(1):79-104.
Bavaresco L, et al. “Stilbene compounds: from the grapevine to wine.” Drugs Exp Clin Res. 1999;25(2-3):57-63.
Bertelli A, et al. “Plasma and tissue resveratrol concentrations and pharmacological activity.” Drugs Exp Clin Res. 1998;24:133–8.
Bertram JS. “Carotenoids and gene regulation.” Nutr Rev. 1999;57(6):182-191.
Bishayee A. “Cancer prevention and treatment with resveratrol: from rodent studies to clinical trials.” Cancer Prev Res (Phila). 2009 May;2(5):409-18.
Burger KN, et al. “Dietary fiber, carbohydrate quality and quantity, and mortality risk of individuals with diabetes mellitus.” PLoS One. 2012;7(8):e43127.
Chanet A, et al. “Citrus flavanones: what is their role in cardiovascular protection?” J Agric Food Chem. 2012 Sep 12;60(36):8809-22.
Chang J, et al. “Low-dose pterostilbene, but not resveratrol, is a potent neuromodulator in aging and Alzheimer’s disease.” Neurobiologu of Aging. 2012;33(9):2062-2071.
Chung KT. “Tannins and human health: a review.” Crit Rev Food Sci Nutr. 1998 Aug;38(6):421-64.
Chun OK, et al. “Estimated dietary flavonoid intake and major food sources of U.S. adults.” J Nutr. 2007 May;137(5):1244-52.
Grooms KN, et al. “Dietary Fiber Intake and Cardiometabolic Risks among US Adults, NHANES 1999-2010.” Am J Med. 2013 Oct 9. pii: S0002-9343(13)00631-1.
Korte G, et al. “An examination of anthocyanins’ and anthocyanidins’ affinity for cannabinoid receptors.” J Med Food. 2009 Dec;12(6):1407-10.
Krinsky NI, et al. “Biologic mechanisms of the protective role of lutein and zeaxanthin in the eye.” Annu Rev Nutr. 2003;23:171-201.
Ma L & Lin XM. “Effects of lutein and zeaxanthin on aspects of eye health.” J Sci Food Agric. 2010 Jan 15;90(1):2-12.
Norat T, et al. “Fruits and Vegetables: Updating the Epidemiologic Evidence for the WCRF/AICR Lifestyle Recommendations for Cancer Prevention.” Cancer Treat Res. 2014;159:35-50.
Pari L & Satheesh A. “Effect of pterostilbene on hepatic key enzymes of glucose metabolism in streptozotocin-and nicotinamide-induced diabetic rats.” Life Sciences. 2006;79(7):641-645.
Sommerburg O, et al. “Fruits and vegetables that are sources for lutein and zeaxanthin: the macular pigment in human eyes.” Br J Ophthalmol. 1998 Aug;82(8):907-10.
Ververidis F, et al. “Biotechnology of flavonoids and other phenylpropanoid-derived natural products. Part I: Chemical diversity, impacts on plant biology and human health.” Biotechnol J. 2007 Oct;2(10):1214-34.
Williamson G & Manach C. “Bioavailability and bioefficacy of polyphenols in humans. II. Review of 93 intervention studies.” Am J Clin Nutr. 2005;81:243S-255S.
Yamaguti-Sasaki E, et al. “Antioxidant capacity and in vitro prevention of dental plaque formation by extracts and condensed tannins of Paullinia cupana.” Molecules. 2007 Aug 20;12(8):1950-63.