I usually add a kiwifruit to my smoothies when I can. They are delicious and they add a nice tart flavor to the smoothie. This is not all kiwifruits do, as it turns out.
Turns out that kiwifruits provide significant benefits to the cardiovascular system in the form of reducing inflammation and lipids that form artery plaque. And amazingly, even one kiwifruit a week will produce these benefits.
Research from Spain’s University of Salamanca, in collaboration with numerous health centers throughout Spain, has recently conducted a large study on kiwi fruit. The research was a cross-sectional study that included 1,469 healthy people – who had no signs of heart disease. The subjects were each tested for the range of cholesterol lipids (fats) as well as triglycerides, fibrinogen and insulin resistance.
By cholesterol lipids, we mean high density lipoprotein-cholesterol (HDL-c), low density lipoprotein-cholesterol (LDL-c) and so on. Increasing research over the past two decades has confirmed that higher levels of HDL-c are associated with a reduced risk of cardiovascular diseases. And higher levels of LDL-c are associated with more heart attacks, strokes and other forms of cardiovascular disease.
As we have shown in other articles in this website, the reason LDL-c increases the risk of heart disease is because these lower-density lipids are oxidized more easily. When they are oxidized, they form free radicals that damage our arteries, producing plaque, inflammation and artery stiffness.
The 1,469 person-study group also completed accelerometry testing, which indicated their level of fitness and exercise.
To understand their particular dietary habits, the researchers had every subject complete a full dietary questionnaire that included kiwi fruit consumption. The questionnaire included 137 food items and tracked the frequency of consumption.
The frequency of consumption data measured the consumption of each food using a scale of nine:
• almost never
• 1-3 times per month
• 2-4 times per week
• 5-6 times per week
• Once per day
• 2-3 times per day
• 4-6 times per day
• More than 6 times per day
This allowed the researchers to then establish how many kiwis were eaten on average per week. And this weekly kiwifruit consumption number became the standard measurement to test against.
The research determined that approximately a quarter of the group (24 percent) ate at least one kiwi fruit per week.
The researchers found that eating at least one kiwi fruit per week resulted in an average HDL-cholesterol difference of 4.5 milligrams per deciliter (mg/dL) lower than those that didn’t eat kiwis. Those who ate at least one kiwi a week also had on average 20 milligrams per deciliter (mg/dL) lower levels of triglycerides and 13.22 milligrams per deciliter (mg/dL) lower fibrinogen levels.
These are significant numbers, as anyone who has had their blood lipid/cholesterol levels checked recently will know. Low levels of the “good” HDL-c are anything less than about 45 mg/dL while high levels are anything above 60. This means that a difference of 4.5 can make a real difference.
Eating at least one kiwi a week also made for significant differences in triglycerides and fibrinogen levels: Differences of 20 milligrams per deciliter and over 13 points respectively. Normal levels of triglycerides are considered less than 150 mg/dL, and over 150 mg/dL is considered above normal, while anything over 200 mg/dL is high, and considered at high risk of heart disease. Many doctors simply consider levels over 200 mg/dL as cardiovascular disease.
Same with high fibrinogen levels. High fibrinogen levels indicate higher levels of inflammation within the cardiovascular system. Levels over 400 mg/dL are considered high, while the normal range is 150 mg/dL to 300 mg/dL.
According to the guidelines of the American Association of Clinical Endocrinologists, triglycerides over 200 mg/dL warrant prescriptions of statins or other lipid drugs. So 20 points lower for anyone at this borderline make a real difference.
High fibrinogen levels have been linked to a variety of heart and artery conditions, including heart attacks, strokes and cardiovascular disorders, including ischemic heart disease, stroke and other types of embolism blockages.
The researchers also found that eating kiwifruit prevented high cholesterol-lipid levels. It reduced the risk of high fibrinogen levels (above 400 mg/dL) by 32 percent. It reduced the risk of low HDL-Cholesterol levels (less than 45 mg/dL) by 43 percent.
In addition to these cardiovascular benefits, eating at least one kiwifruit per week significantly decreased insulin resistance among the study group. It decreased the risk of having high levels of insulin resistant – by 39 percent.
Certainly, reducing insulin resistance is also a benefit to the cardiovascular system. This is because high blood sugar levels also increase artery-damaging free radicals.
Remember that these benefits were only from one kiwifruit a week. Other probable relationships were eliminated with the calculations.
This is not the only study that has shown kiwifruit’s ability to increase cardiovascular health.
A 2004 study from the University of Oslo tested kiwifruit consumption in a cross-over study for 28-days. The research found that eating two or three kiwifruits per day for just under a month reduced triglycerides by 15 percent. The 2-3 kiwifruits per day also reduced platelet aggregation by 18 percent.
A healthier cardiovascular system is not the only benefit of kiwifruit.
A 2001 study from the UK’s Rowett Research Institute found that kiwifruit protected DNA from damage among human cells.
A 2004 study from Rome’s Regional Health Authority studied 18,737 children from Central and Northern Italy and found that children that ate more kiwifruit and other citrus had 44 percent less wheezing, 32 percent less shortness of breath and 25 percent less chronic coughing.
The kiwifruit (Actinidia deliciosa) also goes by the name of Chinese gooseberry, as it is indigenous throughout Asia – including Korea, Japan and China. However, a number of cultivars of kiwi are grown around the world. This includes South America, Southern Europe, the U.S., Australia and New Zealand.
New Zealand is so famous for their delicious kiwifruit that New Zealanders often refer to themselves – as others do – as “kiwis.”
A 2011 study from Japan’s Teikyo University found that kiwifruit had greater antioxidant potential than oranges and grapefruits. They also found that the gold kiwis had greater antioxidant potential.
Kiwi fruit has significant levels of polyphenols and other antioxidant micronutrients. Kiwi also contains considerable fiber – a good 8-10 percent of recommended daily values – and that’s without the peel.
Most will peel away the kiwifruit’s furry peel. But that’s not the best way to benefit from the kiwifruit. The furry peel chews up easily and provides a wealth of additional nutrients in addition to the extra fiber. Personally, I cut off the pedicel and calyx (top and bottom knobs) and just drop the whole fruit into my smoothie – peel and all.
A good-sized kiwifruit will contain close or slightly above a full-day’s recommended daily intake (DVI) of vitamin C. It also contains a third of our daily need for vitamin K, and contains significant amounts of vitamin E, potassium, folate and dietary fiber.
But it’s the kiwifruit’s polyphenols that appear to provide its significant cardiovascular and other benefits.
Recio-Rodriguez JI, Gomez-Marcos MA, Patino-Alonso MC, Puigdomenech E, Notario-Pacheco B, Mendizabal-Gallastegui N, de la Fuente Ade L, Otegui-Ilarduya L, Maderuelo-Fernandez JA, de Cabo Laso A, Agudo-Conde C, Garcia-Ortiz L; EVIDENT Group. Effects of kiwi consumption on plasma lipids, fibrinogen and insulin resistance in the context of a normal diet. Nutr J. 2015 Sep 15;14:97. doi: 10.1186/s12937-015-0086-0.
Duttaroy AK, Jørgensen A. Effects of kiwi fruit consumption on platelet aggregation and plasma lipids in healthy human volunteers. Platelets. 2004 Aug;15(5):287-92.
Iwasawa H, Morita E, Yui S, Yamazaki M. Anti-oxidant effects of kiwi fruit in vitro and in vivo. Biol Pharm Bull. 2011;34(1):128-34.
Collins BH, Horská A, Hotten PM, Riddoch C, Collins AR. Kiwifruit protects against oxidative DNA damage in human cells and in vitro. Nutr Cancer. 2001;39(1):148-53.
Forastiere F, Pistelli R, Sestini P, Fortes C, Renzoni E, Rusconi F, Dell’Orco V, Ciccone G, Bisanti L. Consumption of fresh fruit rich in vitamin C and wheezing symptoms in children. SIDRIA Collaborative Group, Italy (Italian Studies on Respiratory Disorders in children and the Environment). Thorax. 2000 Apr;55(4):283-8.
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