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It’s strawberry season! Long touted for their taste, strawberries have drawn little attention for their health benefits
While berries get a lot of attention for their health benefits, most of the spotlight goes to berries like blueberries and cranberries. We rarely hear about the health benefits of strawberries (which are not, technically speaking, a berry). But, that’s changing. Strawberries are sneaking into the spotlight.
Though not as famous in health circles as its more famous cousins, the research is starting to accumulate for the strawberry. Several studies have now shown strawberries to be good for your heart because they improve cholesterol and triglycerides even in overweight people (Br J Nutr 2012;108(5):900-9) and people with metabolic syndrome (Nutr J 2009;28;8:43; Nutr Res 2010;30(7):462-9). Importantly, strawberries not only lower LDL-cholesterol, they also reduce the free radical damage that renders the LDL cholesterol dangerous (Metabolism 2008;57(12):1636-44).
But that’s not the only mechanism by which strawberries benefit the cardiovascular system. A double-blind study wanted to see what cardiovascular effects strawberries would have on people who were at higher risk of cardiovascular disease. The researchers decided to look at twenty-five adolescent men who were all between the ages of 14 and 18 and who were all overweight or obese. Every day for a week, the men took either 50g of freeze-dried strawberry powder or a placebo. Immediately after taking the strawberry powder, levels of nitrate/nitrite went up, suggesting a relaxing of the blood vessels. At the end of the study, there was no long term effect. But, in the men who experienced the immediate effect, there was a significant increase in the reactive hyperaemia index at the end of the study. Reactive hyperaemia index is a measure of blood vessel responsiveness, and the increase suggests that eating strawberries increases blood flow. This study suggests that, in addition to improving cholesterol and triglycerides and acting as an antioxidant, strawberries can also improve cardiovascular health by dilating blood vessels and improving blood flow even in people who, because of being overweight, are at increased risk of cardiovascular disease (British Journal of Nutrition 2016;116(4):639-47).
And, speaking of acting as an antioxidant, a massive study of 93,600 women found that eating blueberries and strawberries reduces the risk of heart attack by 34% because of their rich anthocyanin flavonoid content (Circulation 201315;127(2):188-96).
Not surprisingly, since strawberries are rich in flavonoids and since they prevent free radical damage to LDL cholesterol, freeze-dried strawberry has been shown to increase antioxidant capacity. In a controlled study of sixty people with abdominal obesity, strawberry increased antioxidant capacity and glutathione levels compared to the control (J Nutr Metab 2016;2016:3910630).
Obesity is an important risk factor for osteoarthritis. This double-blind study gave obese people with osteoarthritis of the knee either a placebo or 50g a day of freeze-dried strawberry powder for twelve weeks. Markers of inflammation were significantly reduced in the strawberry group compared to the placebo group. The strawberry powder also significantly reduced pain and cartilage degradation (Nutrients 2017:28;9(9):949).
A large study of 16,010 women over the age of seventy found that eating more strawberries is associated with significant delaying of cognitive aging by up to 2.5 years. The benefit is believed to be because of the flavonoids in the strawberries (Ann Neurol 2012;72(1):135-43).
Blood Sugar Control
A single-blind study of fourteen overweight adults found that consuming a strawberry drink two hours before a meal significantly reduces rises in blood sugar after eating. This study suggests that strawberry also improves insulin sensitivity (Food Funct 2016;7(12):4745-4752).
As these ten studies suggest, strawberries are beginning to attract the attention they deserve as a health food.