Pomegranate: the heart-healthy fruit

A new study, published in the Journal of Nutritional Science, has found that pomegranate juice can reduce key cardiovascular risk factors in overweight adults (1). While the fruit’s impressive antioxidant content has been credited with its success, this study reveals that there might be another secret to the fruit’s benefits.

pomegranate
Pomegranate can help to reduce insulin levels and blood pressure.

Pomegranate juice has already been shown to have some remarkable health benefits with clinical studies showing it can reduce blood pressure, improve blood sugar control and even reduce the thickness of arteries. These studies have attributed the heart-healthy effects of pomegranate to its extraordinarily high antioxidant value (2), which is certainly a huge benefit. However, this study looked at the effects of pomegranate juice on cortisol levels.

Cortisol is a hormone released by the adrenal gland in response to stress. Excessive levels of cortisol are linked to both high blood pressure and insulin resistance (3,4).

In addition to measuring cortisol levels, the researchers also measured several markers of heart disease, including blood pressure, arterial elasticity, insulin resistance and blood sugar levels.

The study was a randomised cross-over design, meaning that each volunteer essentially serves as his or her own ‘control’ making the study results more reliable. In this case, the male and female volunteers were randomly assigned to receive pomegranate juice or a placebo drink for 4 weeks. After a 1-week break, the groups were then swapped, so that everybody had been tested with both the pomegranate and the placebo drink.

At the end of the study, it was found that the pomegranate juice was linked with a significant reduction in blood pressure, as well as a decrease in insulin levels and insulin resistance. Interestingly, there was also a reduction in the cortisol levels of the juice drinkers, and an increase in levels of cortisone, which is the inactivated form of cortisol. It appears that pomegranate juice might actually boost health by preventing cortisone from being converted to active cortisol.

In short, the study suggests that the benefits of pomegranate juice and not simply a result of its impressive antioxidant content. It also appears to lower cortisol levels, which in turn has a direct effect on the heart and blood vessels.

Cardiovascular disease remains the UK’s biggest killer. According to the British Heart Foundation, this disease is responsible for one third of deaths of both men and women in Britain.

One of the biggest concerns about cardiovascular disease is that it can go undetected for many years, causing the illness to be labelled a ‘silent killer’. In fact, often the first symptom is a stroke or a heart attack meaning that sufferers may then face invasive but necessary treatments such as bypass surgery or angioplasty.

For this reason, small and simple measures to reduce your risk of cardiovascular disease are invaluable. As positive results have been found by drinking as little as 2 ounces of pomegranate juice daily (5), a daily serving of pomegranate juice might just be a change worth making.

Written by Nadia Mason, BSc MBANT NTCC CNHC.

References

1. Catherine Tsang, Nacer F. Smail, S. Almoosawi, I. Davidson and Emad A. S. Al-Dujaili. (2012) Intake of polyphenol-rich pomegranate pure juice influences urinary glucocorticoids, blood pressure and homeostasis model assessment of insulin resistance in human volunteers.  J Nutr Sci, 1:9

2. Seeram NP, Aviram M, Zhang Y, et al. (2008) Comparison of antioxidant potency of commonly consumed polyphenol-rich beverages in the United States. J Agric Food Chem 56, 1415–1422

3. Duclos M, Pereira PM, Barat P, et al. (2005) Increased cortisol bioavailability, abdominal obesity and the metabolic syndrome in obese women. Obes Res 13, 1157–1166.

4. Kidambi S, Kitchen JM, Grim CE, et al. (2007) Association of adrenal steroids with hypertension and the metabolic syndrome in blacks. Hypertension 49, 704–711.

5. 8. Aviram M, Dornfeld L. Pomegranate juice consumption inhibits serum angiotensin converting enzyme activity and reduces systolic blood pressure. Atherosclerosis. 2001 Sep;158(1):195-8.

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