What's New and Beneficial About Strawberries
posted by Research Admin 1 on 11 February 2020
The World's Healthiest Foods, February 2020
Recent studies have examined the total antioxidant capacity (TAC) of strawberries, not only in comparison with other fruits, but also in comparison with foods in other food groups. Researchers now know that about 30% of the TAC in strawberries is provided by their vitamin C content. At WHFoods, strawberries rank as our number 5 source of vitamin C among all 100 WHFoods, and as our number 2 source of vitamin C among all 19 of our profiled fruits. In one research study, this vitamin C richness of strawberries helped them to score 27th among all commonly consumed U.S. foods (both fruits and non-fruits) in terms of their total antioxidant capacity. And in this same study, strawberries came in fourth among all fruits commonly consumed in the U.S. in terms of their TAC—just behind blackberries, cranberries, and raspberries. It's also worth noting here that all four of these fruits scoring highest in TAC are berries—which is one of the reasons that we include berries 6 days of the week in our 7-Day Meal Plan.
Research on the antioxidant content of strawberries is providing us with stronger and stronger evidence about their ability to lower risk of cardiovascular disease. Study-by-study, the piece parts here keep adding up: after consumption of strawberries, there is less platelet aggregation, less lipid peroxidation, less malondialdehyde formation, and more free radical scavenging activity as well as activity of the enzyme paraoxonase-1 (PON-1). Increased activity of PON-1 is an area of growing interest in research on coronary artery disease since this enzyme is able to help break down (hydrolyze) lipid hydroperoxides (LOOH). Excessive presence of LOOH in the blood vessels can increase risk of damage to those blood vessels due to the highly reactive nature of LOOH. In these cardiovascular-focused studies, the amount of strawberries consumed per day has varied between approximately 2–4 cups, and the period of time required in order to see cardiovascular benefits has varied between approximately 10–30 days.
Improved regulation of blood sugar is a health benefit that appears more and more likely based on the findings from recent studies on strawberry consumption. Especially following consumption of a meal, researchers are finding better regulation of insulin and blood sugar levels in connection with strawberry intake. Numerous mechanisms are under investigation here, including release of incretin hormones like GLP-1 (glucagon-like peptide 1) and GIP (glucose-dependent insulinotropic polypeptide) and alterations in the activity of carb-related enzymes like alpha-glucosidase and alpha-amylase. Most assessments of strawberries show a glycemic index (GI) value of approximately 40. This GI for strawberries would not only be considered low, but is also considerably lower than the GI for many other fresh fruits, including apricots, bananas, cantaloupe, pineapple, and watermelon (and, of course, dried fruits like figs which have a more concentrated sugar content after being dried). The low GI of strawberries seems to match up well with new research studies on their blood sugar impact. We would also like to note that among our Top 25 food sources for folate at WHFoods, there are only two fruits: papaya and strawberries. The fact that 1 cup of these berries provide roughly 10% of our daily recommended folate (400 micrograms) might play an important role in their blood sugar impact since folate deficiency has been associated with increased risk of type 2 diabetes and since improvements in type 2 diabetes have been shown with increased intake of folate.
In this highlight section on strawberries, we believe that it is important to point out the difference between certified organic and conventional strawberries in terms of potential pesticide residues. While we support the purchase of organic foods throughout our website, there are some foods for which organic purchase may be especially helpful, and strawberries are one of those foods. According to results from the 2015 Pesticide Data Program administered by the U.S. Department of Agriculture (USDA), well over half of all strawberry samples (706 total) contained pesticide residues. Over 30% contained residues from five different pesticides, and 3.5% contained residues that exceeded established Environmental Protection Agency (EPA) tolerances. One strawberry sample also contained residues from 20 different pesticides among the 38 different types of pesticide residues found on the strawberry samples. While certified organic strawberries are definitely not guaranteed to be free of pesticides, the rate of detection on organic strawberries has been far lower than the rate on conventional produce. A 2010-2011 pilot program at the USDA, for example, performed 5,022 analyses on 26 strawberry samples and failed to detect pesticide residues in 5,012 of 5,022 analyzed.
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