Eating Kiwifruit May Help Lower Blood Pressure

    High blood pressure is a significant risk factor for heart disease, and dietary choices can play a crucial role in managing blood pressure levels. Recent research has focused on the potential health benefits of kiwifruit, examining how regular consumption may improve blood pressure, reduce platelet aggregation, and provide additional cardiovascular benefits.

    Lifestyle changes, such as lowering blood pressure and quitting smoking, can reduce the risk of heart disease. Consuming fruits and vegetables also has a positive impact on these health factors.

    In a recent study, researchers investigated whether consuming kiwifruits or other antioxidant-rich foods could lower blood pressure and reduce platelet aggregation (the clumping of blood cells associated with heart health) among male smokers aged 44–74 years (n = 102). Participants were divided into three groups: one ate three kiwifruits daily, another consumed various antioxidant-rich foods, and a control group made no dietary changes (1).

    After eight weeks, the group consuming kiwifruit experienced a significant drop in blood pressure: systolic pressure decreased by 10 mmHg and diastolic by 9 mmHg (p<0.05 for both). The antioxidant-rich diet group saw a reduction in systolic blood pressure only among those who initially had high blood pressure. Additionally, the kiwifruit group showed a 15% reduction in platelet aggregation and an 11% decrease in angiotensin-converting enzyme (ACE) activity, an enzyme related to elevated blood pressure. These benefits were not observed in the antioxidant-rich diet group (1).

    The researchers suggest that regular consumption of kiwifruits may be particularly beneficial for reducing blood pressure and platelet aggregation among smokers. They theorize that the reduction in ACE activity, an enzyme that increases blood pressure by producing angiotensin-II (a substance that constricts blood vessels), could explain the beneficial effects (1).

    Earlier studies have shown that kiwifruits and other antioxidant-rich plant foods can inhibit ACE activity in laboratory tests, likely by binding directly to the enzyme. Medical research indicates that ACE-blocking drugs typically lower blood pressure by approximately 8 mmHg (systolic) and 5 mmHg (diastolic) in hypertensive individuals. This study demonstrates similar benefits achieved simply by eating three kiwifruits daily (1).

    However, the specific components of kiwifruit responsible for these health effects remain unclear. Although kiwifruits contain high levels of vitamin C and polyphenols, similar antioxidants in other foods did not yield the same results in this study. Researchers suggest that kiwifruits might contain unique polyphenols contributing to these specific health benefits.

    Another study examined how consuming two kiwifruits at breakfast impacted health indicators over seven weeks in 43 healthy Asian adults. Participants were randomly divided into two groups: one group drank 500 mL of carbonated water (control), while the other group drank 500 mL of carbonated water and ate two kiwifruits. Diet records and blood samples were collected at baseline and during the study (2).

    The kiwifruit group consumed more fructose, vitamin C, vitamin E, and carbohydrates than the control group. However, no significant differences were observed between groups in blood sugar, insulin, uric acid, triglycerides, or cholesterol levels. There was a slight but statistically significant decrease (2.7 mmHg) in systolic blood pressure for the kiwifruit group compared to the control (2).

    Eating two kiwifruits with breakfast increased antioxidant vitamin intake without negatively affecting metabolic factors. Regularly including kiwifruits in breakfast routines might thus offer modest health benefits (2).

    A third study evaluated daily kiwifruit consumption on 118 adults with slightly elevated blood pressure or mild hypertension. Participants ate either three green kiwifruits or one apple daily for eight weeks. Blood pressure was monitored continuously (24-hour ambulatory blood pressure) and periodically in a clinical setting (office blood pressure) (3).

    Participants consuming three kiwifruits daily experienced a greater reduction in 24-hour blood pressure compared to the apple group: systolic pressure decreased by an additional 3.6 mmHg and diastolic by 1.9 mmHg. These improvements were statistically significant, although office-based measurements and endothelial function tests showed no significant differences (3).

    The study concluded that regularly eating three kiwifruits per day could effectively lower blood pressure in adults with moderately elevated levels. The benefits appear linked to increased potassium, vitamin C, antioxidant intake, and ACE activity reduction rather than improved endothelial function alone (3).

    Lastly, a pilot study involving 24 prediabetic participants consuming two SunGold kiwifruits daily for 12 weeks reported significant increases in vitamin C levels, reductions in blood pressure (systolic by 6 mmHg, diastolic by 4 mmHg), and decreased waist measurements. Slight changes in gut bacteria were observed, potentially influenced by kiwifruit's fiber and polyphenols, though further research is needed to fully understand these mechanisms (4).

    Collectively, these studies highlight the potential cardiovascular benefits of regular kiwifruit consumption, particularly its ability to lower blood pressure and enhance overall health through increased antioxidant intake. While more research is needed to fully understand the specific mechanisms, kiwifruit appears to be a valuable addition to a heart-healthy diet.

References:

1.         Karlsen A, Svendsen M, Seljeflot I, Laake P, Duttaroy AK, Drevon CA, Arnesen H, Tonstad S, Blomhoff R. Kiwifruit decreases blood pressure and whole-blood platelet aggregation in male smokers. J Hum Hypertens. 2013 Feb;27(2):126-30. doi: 10.1038/jhh.2011.116. Epub 2012 Jan 19. PMID: 22258209.

2.         Monro J, Lubransky A, Mishra S, Haszard J, Venn B. Metabolic and Blood Pressure Effects of Consuming Two Kiwifruit Daily for 7 Weeks: A Randomised Controlled Trial. Nutrients. 2022 Jun 28;14(13):2678. doi: 10.3390/nu14132678. PMID: 35807858; PMCID: PMC9268970.

3.         Svendsen M, Tonstad S, Heggen E, Pedersen TR, Seljeflot I, Bøhn SK, Bastani NE, Blomhoff R, Holme IM, Klemsdal TO. The effect of kiwifruit consumption on blood pressure in subjects with moderately elevated blood pressure: a randomized, controlled study. Blood Press. 2015 Feb;24(1):48-54. doi: 10.3109/08037051.2014.976979. Epub 2014 Dec 8. PMID: 25483553.

4.         Wilson R, Willis J, Gearry RB, Hughes A, Lawley B, Skidmore P, Frampton C, Fleming E, Anderson A, Jones L, Tannock GW, Carr AC. SunGold Kiwifruit Supplementation of Individuals with Prediabetes Alters Gut Microbiota and Improves Vitamin C Status, Anthropometric and Clinical Markers. Nutrients. 2018 Jul 12;10(7):895. doi: 10.3390/nu10070895. PMID: 30002355; PMCID: PMC6073280.

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