Umm..mm..mm strawberries! Delicious to bite into, juicy and sweet, with a gorgeous ruby glow on the outside. There are enough reasons right there to eat a strawberry. But behind their alluring taste and appearance, there are many more enticements to eat these little fruits.
Nutrients in Strawberries
With only 49 calories, one half cup of sliced strawberries contains 3 gm of fiber, 90 mg Vitamin C (more than 100% of the daily recommended amount), 233 gm potassium and 0.6 mg of manganese (29% of your daily requirement). They are also good sources of many B vitamins including folate, as well as Vitamin E, iron, magnesium, phosphorus and copper (1).
Super-Nutrients in Strawberries
The power behind the health benefits of strawberries however are their phytochemicals. Phytochemicals are compounds produced by plants that help them thrive and thwart competitors, predators and pathogens. It is these nutrients that make strawberries a “functional food”, one that has positive effects on health beyond their basic nutrition and can potentially reduce the risk of diseases and promote optimal health. Strawberries are at the top of all fruits and vegetables in polyphenol content (and consequently in their antioxidant capacity) (2,3,4,5). Phytochemical-rich foods such as strawberries are linked with a reduction in many chronic diseases including cardiovascular disease, some cancers and neurodegenerative diseases (6).
A List of Some of the Phytochemicals in Strawberries (6,7,8)
PHENOLIC COMPOUNDS including;
POLYPHENOLS such as
Flavonoids (red, blue and purple pigments);
Further divided into
Flavonols (quercetin, kaempferol, myricetin and fisetin)
Flavanols (catechins, proanthocyanidins)
Anthocyanidins and anthocyanins
Hydrolysable tannins (ellagic acid and gallotannins)
AROMATIC ACIDS such as
Hydroxycinnamic acids (chlorogenic acid)
Steroids (phytosterols, tocopherols (Vitamin E))
Health Benefits of Strawberries
Anticancer effects of strawberries are exerted through a number of pathways. Strawberries provide antioxidants against reactive oxygen species through their phenol constituents which can protect DNA from damage. Strawberry phytochemicals also modulate gene expression, suppress cell proliferation, inhibit angiogenesis (the growth of new blood vessels needed to feed tumours) and encourage programmed cell death (apoptosis). As if that is not enough, strawberries can inhibit cell mutation, sensitize tumour cells to chemotherapeutic agents and provide protection from chemotherapy-associated toxicity (6,7).
Two related studies from the NIH‐AARP Diet and Health Study looked at the relationship between strawberry intake and the onset of certain cancer types. The first study found a statistically significant association between risk of esophageal cancer and intake of Rosacea fruits (apples, peaches, nectarines, plums, pears and strawberries) with the subjects eating higher amounts of these fruits dropping their risk of esophageal cancer by 56% (9). The second trial similarly found a 40% drop in the risk of onset of head and neck cancers in participants eating higher amounts of Rosacea fruits compared to those eating the lowest quantities (10).
Consumption of strawberries can reduce risk factors for cardiovascular disease with such effects as lowering blood pressure, reducing obesity, reducing oxidative stress and inflammation, lowering blood sugar levels, and reducing high serum lipids levels (11). Data from the Iowa Women’s Health Study, which included over 34,000 postmenopausal women, revealed that eating strawberries was linked to significant reduction in death from cardiovascular disease. Researchers credited this benefit to the high content of anthocyanidins, flavanones and flavones in strawberries (12).
Participants of the Nurses’ Health Study were examined for the effects of eating strawberries and blueberries on heart health. It was observed that eating just three servings of blueberries or strawberries a week was associated with a 32% reduction in the incidence of heart attacks in young and middle-aged women compared to eating berries once a month or less. This inverse association was independent of other risk factors for cardiovascular disease (13).
Other data from the Nurses’ Health Study and also the Health Professionals Follow-Up Study found that participants ingesting the highest level of anthocyanins (predominantly from blueberries and strawberries) showed an 8% reduction in risk of hypertension compared to those eating the lowest amount of anthocyanins (14).
A randomized controlled trial found that supplementation with strawberries caused a 10% decrease in total cholesterol and an 11% reduction in LDL-cholesterol (harmful cholesterol). These benefits were credited to the content of phytosterols, polyphenols and fiber in strawberries (15).
Interventional studies have shown improvements in blood lipid levels, oxidation of LDL-cholesterol, total antioxidant capacity and glucose metabolism. These healthy effects appear to be mediated by increasing nitric oxide synthesis in blood vessels and decreasing oxidative stress and inflammation (16).
Another randomized controlled trial illustrated that eating moderate amounts of berries daily (100 gm) caused a significant 5.2% increase in blood HDL-cholesterol levels (beneficial cholesterol). This change was attributed to the polyphenols which were present in the berry-eating group at levels three -times higher than those of the control group (17).
A study of over 38,000 female health professionals in the United States found lower markers of inflammation among those ingesting more strawberries. Participants consuming 2 or more servings a week of strawberries had a 14% lower level of C-reactive protein, a protein present in the blood that indicates inflammation (18).
Blood sugar levels
Studies have shown improvements in the absorption and metabolism of sugars which are thought to stem from eating polyphenols in foods such as strawberries. For instance, refined sugar is easily and quickly absorbed after it is eaten, creating a spike in blood sugar level. Eating berry puree results in a much smaller and slower blood sugar increase. Surprisingly, ingesting the same amount of berry puree with added refined sugar substantially reduces the speed and peak in blood sugar, even though the total amount of sugar eaten is greater (16,19).
Higher intake of strawberries, with their rich concentrations of anthocyanins and flavonoids, are thought to be behind the lower weight gain and improved weight maintenance in adults in a study from 2016, indicating that strawberry ingestion may help to prevent obesity. Researchers hypothesize that these phytonutrients may be increasing glucose uptake in muscle and/or decreasing glucose uptake in fat tissue (20).
Aging and Brain Health
Many studies have looked at the positive effects that strawberries can have on cognition.
Animal studies have shown that strawberries can slow age-related changes in the brain such as reduction in the function of neurons and difficulties with working memory and motor behaviour (6,21,22). They have also shown reversal of aging in neurons. The polyphenol constituents (such as flavonoids) and the antioxidant activity present in strawberries were credited with these positive results, suggesting that nutritional intervention with fruits and vegetables high in these nutrients may play an important role in preventing and even reversing the effects of oxidative stress in aging brains. (23). Other research has shown that diets high in flavonoid antioxidant-containing foods such as strawberries and spinach can reverse mild cognitive decline in middle-aged test animals through the reduction of inflammation and oxidative stress in the brain (24). Furthermore, dietary polyphenols from strawberries appear to improve age-related mitochondrial dysfunction and reduce the DNA damage commonly appearing during aging through their antioxidant activities (25).
In humans, larger intakes of strawberries, apples, pears and peppers have been linked to improved cognition. A study in older women calculated that eating at least two half-cup servings of blueberries or strawberries every week could delay cognitive aging by up to 2.5 years. Once again, these positive effects were attributed to the rich content of flavonoids, especially anthocyanidins, in these foods (26).
Other research suggests that eating berries high in antioxidants may increase “health span” by helping to reverse cognitive and motor dysfunctions caused by aging (27).
Lung function in human beings generally begins to decline during the third decade of life although this occurs at different rates among different individuals. Lower lung function is a strong predictor of increased hospitalizations and early mortality. Strawberries offer a possible pathway to slow this deterioration.
Foods high in anthocyanins have been associated with a reduction in age-related decline in lung function in elderly men. Food-based analyses reveal that intake of blueberries, strawberries and red wine are the largest contributors to anthocyanin intake in North America. It follows that berries of all kinds, as a rich source of anthocyanins, could play a role in decreasing this risk (28).
Getting Strawberries Into Your Diet
Strawberries in all forms have positive health effects. This means you can eat them fresh, frozen, canned, dried or made into juice or jam. However, fresh or frozen strawberries have the highest amounts of the super-nutrients discussed in this article.
Processing can significantly decrease phytochemical content of these berries. For example, pureeing or juicing berries, especially with the use of heat, can induce losses of Vitamin C, anthocyanin content and antioxidant capacity (29). Processing of strawberries for jam causes substantial losses of polyphenols and specifically anthocyanins. Storage of jam further increases these losses (30). On the other hand, frozen strawberries contain significantly higher levels of Vitamin C and polyphenols compared to freeze-dried or air-dried berries (29,31).
The final message here is an enjoyable one. Eat a bowl of fresh-sliced strawberries or whip up a batch of plant-based strawberry frozen dessert, add strawberries to your smoothies and salads or use them as a garnish for soups. Make strawberry sauce and drizzle it over pancakes or toast or dip whole strawberries in melted dark chocolate for an extra-special treat. In short, enjoy this delicious and healthy fruit as often as you can.
2 Basu, A., Morris, S., Nguyen, A., Betts, N.M., Fu, D., Lyons, T.J. Effects of Dietary Strawberry Supplementation on Antioxidant Biomarkers in Obese Adults with Above Optimal Serum Lipids. J Nutr. & Metab. Volume 2016; Article ID 3910630. https://doi.org/10.1155/2016/3910630.
3 Wang, S.Y., Lin, H.S. Antioxidant activity in fruits and leaves of blackberry, raspberry, and strawberry varies with cultivar and developmental stage. J. Agric. Food Chem. 2000; 48:140-146.
4 Proteggente, A.R., Pannala, A.S., Paganga, G., Van Buren, L., Wagner, E., Wiseman, S., Van De Put, F., Dacombe, C., and Rice-Evans, C.A. The antioxidant activity of regularly consumed fruit and vegetables reflects their phenolic and vitamin c composition. Free Radic. Res. 2002; 36:217-233.
5 P’erez-Jim’enez, J., Neveu, V., Vos, F., and Scalbert, A. Identification of the 100 richest dietary sources of polyphenols: An application of the phenolexplorer database. Eur. J. Clin. Nutr. 2010; 64:S112-S120.
6 Seeram, N. Strawberry phytochemicals and human health: A review. January, 2007.
7 Seeram, N.P. Berry fruits for cancer prevention: current status and future prospects. J Agric Food Chem. 2008 Feb 13;56(3):630-635.
9 Freedman, N.D., Park, Y., Subar, A.F., Hollenbeck, A R., Leitzmann, M.F., Schatzkin, A., Abnet, C.C. Fruit and vegetable intake and esophageal cancer in a large prospective cohort study. Int. J. Cancer. 2007;121:2753-2760.
10 Freedman, N.D., Park, Y., Subar, A.F., Hollenbeck, A.R., Leitzmann, M.F., Schatzkin, A.,Abnet, C.C. Fruit and vegetable intake and head and neck cancer risk in a large United States prospective cohort study. Int. J.Cancer. 2008; 122:2330-2336.
11 Basu, A., Nguyen, A., Betts, N.M., Lyons, T. J. Strawberry as a functional food: an evidence-based review. Crit Rev Food Sci Nutr. 2014;54(6):790-806.
12 Mink, P.J., Scrafford, C.G., Barraj, L.M.,Harnack, L., Hong, C.P., Nettleton, J.A., Jacobs, D.R., Jr. Flavonoid intake and cardiovascular disease mortality: A prospective study in postmenopausal women. Am. J. Clin. Nutr. 2007; 85:895-909.
13 Cassidy, A., Mukamal, K.J., Liu, L., Franz, M., Eliassen, A.H., Rimm, E.B. High anthocyanin intake is associated with a reduced risk of myocardial infarction in young and middle-aged women. Circulation. 2013 Jan 15 ;127(2):188-196.
14 Cassidy, A., O’Reilly, E.J., Kay, C., Sampson, L., Franz, M., Forman, J.P., Curhan, G., and Rimm, E.B. Habitual intake of flavonoid subclasses and incident hypertension in adults. Am. J. Clin. Nutr. 2010. 93:338-347.
15 Basu, A., Fu, D.X., Wilkinson, M., Simmons, B., Wu, M., Betts, N M., Du, M., Lyons, T.J. Strawberries decrease atherosclerotic markers in subjects with metabolic syndrome. Nutr. Res. 2010; 30:462-469.
16 Basu, A., Rhone, M., Lyons, T.J. Berries: emerging impact on cardiovascular health. Nutr Rev. 2010 Mar ;68(3):168-177.
17 Erlund, I., Koli, R., Alfthan, G., Marniemi, J., Puukka, P., Mustonen, P.,Mattila, P., Jula, A. Favorable effects of berry consumption on platelet function, blood pressure, and hdl-cholesterol. Am. J. Clin. Nutr. 2008; 87:323-331.
18 Sesso, H.D., Gaziano, J.M., Jenkins, D.J., and Buring, J.E. Strawberry intake, lipids, c-reactive protein, and the risk of cardiovascular disease in women. J. Am. Coll. Nutr. 2007; 26:303-310.
19 T¨orr¨onen, R., Sarkkinen, E., Tapola, N., Hautaniemi, E., Kilpi, K., Niskanen, L. Berries modify the postprandial plasma glucose response to sucrose in healthy subjects. Br. J. Nutr. 2010;103:1094-1097
20 Bertoia ML, Rimm EB, Mukamal KJ, Hu FB, Willett WC, Cassidy A. Dietary flavonoid intake and weight maintenance: three prospective cohorts of 124,086 US men and women followed for up to 24 years. BMJ. 2016;352:i17. Published 2016 Jan 28. doi:10.1136/bmj.i17
21 Joseph, J.A., Shukitt-Hale, B., Denisova, N.A., Bielinski, D., Martin, A., McEwen, J.J., Bickford, P.C. Reversals of age-related declines in neuronal signal transduction, cognitive, and motor behavioral deficits with blueberry, spinach, or strawberry dietary supplementation. J Neurosci. 1999 Sep 15;19(18):8114-8121.
22 Shukitt-Hale, B., Bielinski, D.F., Lau, F.C., Willis, L.M., Carey, A.N., Joseph, J.A. The beneficial effects of berries on cognition, motor behaviour and neuronal function in ageing. Br J Nutr. 2015 Nov 28; 114(10):1542-1549.
23 Joseph, J.A., Shukitt-Hale, B., Denisova, N.A., Prior, R.L., Cao, G., Martin, A., Taglialatela, G., Bickford, P.C. Long-term dietary strawberry, spinach, or vitamin e supplementation retards the onset of age-related neuronal signal-transduction and cognitive behavioral deficits. J. Neurosci. 1998; 18:8047-8055.
24 Millin, P.M., Rickert, G.M. Effect of a Strawberry and Spinach Dietary Supplement on Spatial Learning in Early and Late Middle-Aged Female Rats. Antioxidants (Basel). 2018 Dec 20;8(1). pii: E1.
25 Giampieri, F., Alvarez-Suarez, J.M., Cordero, M.D., Gasparrini, M., Forbes-Hernandez, T.Y., Afrin, S., Santos-Buelga, C., et al. Strawberry consumption improves aging-associated impairments, mitochondrial biogenesis and functionality through the AMP-activated protein kinase signaling cascade. Food Chem. 2017 Nov 1;234:464-471.
26 Devore, E.E., Kang, J.H., Breteler, M.M., Grodstein, F. Dietary intakes of berries and flavonoid in relation to cognitive decline. Ann Neurol. 2012 Jul;72(1):135-143.
27 Joseph, J.A., Shukitt-Hale, B., Willis, L.M. Grape juice, berries, and walnuts affect brain aging and behavior. J. Nutr.2009; 139:1813S-1817S.
28 Mehta, A.J., Cassidy, A., Litonjua, A.A., Sparrow, D., Vokonas, P., Schwartz, J. Dietary anthocyanin intake and age-related decline in lung function: longitudinal findings from the VA Normative Aging Study. Am J Clin Nutr. 2016 Feb; 103(2):542-550.
29 Klopotek,Y., Otto, K., B¨ohm, V. Processing strawberries to different products alters contents of vitamin c, total phenolics, total anthocyanins, and antioxidant capacity. J. Agric. Food Chem. 2005; 53:5640-5646.
30 Ngo, T., Wrolstad, R.E., Zhao, Y. Color quality of Oregon strawberries-impact of genotype, composition, and processing. J. Food Sci. 2007; 72:C025-C032.
31 Asami, D.K., Hong,Y J.,Barrett, D.M., Mitchell, A.E. Comparison of the total phenolic and ascorbic acid content of freeze-dried and air-dried marionberry, strawberry, and corn grown using conventional, organic, and sustainable agricultural practices. J. Agric. Food Chem. 2003; 51:1237-1241.
This is going to help me get going on a new strawberry patch.
Good to hear Peter!
Thanks for the info on strawberries Deb. I love to just eat them fresh. I knew they were good for me but I didn’t know why…
Truly a delicious treat Ruth!