Pistachio diet improves erectile function parameters and serum lipid profiles in patients with erectile dysfunction
Penile erection is a hemodynamic process involving increased arterial inflow and restricted venous outflow, coordinated with corpus cavernosum and penile arterial smooth muscle relaxation. Any problem in this mechanism results in ED, and its etiology is generally multifactorial. Diabetes, hypertension, high serum cholesterol level, peripheral vascular disease and cardiac problems are significantly
found together with ED. However, vascular reasons predominate in the etiology of ED and it frequently appears along with atherosclerosis. It is known that atherosclerotic lesions prevent blood flow into cavernosal tissues resulting in ED. Pistachio (Pistacia vera L.), a member of the Anacardiaceae family, is a native of the arid zones of Central and West Asia and distributed throughout the Mediterranean basin. In Turkey, the pistachio is grown mainly in the city of Gaziantep. Pistachio nuts are rich sources of plant proteins, dietary fibers and especially antioxidant substances (for example, antioxidant vitamins), besides being high in unsaturated fatty acids and low in saturated fatty acids , which may also have cardioprotective effects. Endothelial dysfunction, characterized by impaired nitric oxide bioavailability, precedes the development of atherosclerotic lesions and has been suggested as an important link between ED and cardiovascular disease. Epidemiological studies have demonstrated an association between nut consumption and coronary heart disease. Compared with people who ate nuts less than one time per week, those who ate them 1–4 times per week had a 25% reduced risk of dying from coronary heart disease; people who ate nuts at least 5 times per week showed a 50% reduction in risk. The American Heart Association recommends up to 20% of calories from monounsaturated fat and substituting unsaturated fat from vegetables and nuts. Although various studies exist regarding the positive effects of pistachio nuts on serum lipid profiles, to the best of knowledge, its effect on ED has not been investigated yet. In our study, we investigated the effects of pistachio nuts on International Index of Erectile Function (IIEF) scores, penile color Doppler ultrasound (PCDU) and serum lipid levels in patients with ED.
After a pistachio diet of 3 weeks, total IIEF scores and five domains showed a statistically significant increase. PCDU of patients showed a statistically significant increase in the value of PSV. EDV showed an improvement but it was not statistically significant , which may be attributed to the small number of cases. Pistachio nuts are rich sources of some plant proteins, dietary fibers and especially antioxidant substances, besides being high in unsaturated fatty acids and saturated fatty acids (Table 1). In addition, pistachio nuts are relatively high in the nonessential amino acid arginine, which appears to maintain flexible arteries and to enhance blood flow by boosting nitric oxide, a compound that relaxes blood vessels. Sari et al. demonstrated that a pistachio diet resulted in an improvement in endothelium-dependent vasodilation in normolipidemic healthy young men. Improvement of blood vessel relaxation and endothelium-dependent vasodilatation might be related with significantly increased PSV values in PCDU in our study. Oxidative stress decreased synthesis and bioavailability of endothelial and neuronal nitric oxide. We know that pistachio nuts are rich sources of antioxidant substances (Table 1). Kocyigit et al. reported that a 3-week pistachio diet in healthy volunteers had a favorable effect on oxidative stress. They found a decrease in malondialdehyde level and an increase in antioxidant potential. Serum interleukin-6, total oxidant status, lipid hydroperoxide and malondialdehyde levels were detected to be decreased following administration of 60–100 g pistachio diet for 4 weeks in another study. The antioxidant effects of pistachio against oxidative damage might originate from phytochemicals in its content as resveratrol and anthocyanins have strong free radical scavenging ability. PON1 (paraoxonase 1) and arylesterase, the HDLbound enzyme system, are well-known antioxidant molecules. This enzyme system protects LDL and HDL from oxidation by hydrolyzing activated phospholipids and lipid peroxide products, and thus prevents atherosclerosis. Additionally, PON1 activity was suggested to modulate endothelial functions.20 Ciftci et al.21 reported that the PON1 activity was found significantly lower in patients with ED compared with the control group. Aksoy et al. used 20 and 40% of daily caloric intake pistachio diet for 10 weeks in an experimental study in rats. Consumption of pistachio as 20% of daily caloric intake resulted in a significant improvement in HDL cholesterol and TC/HDL ratio. Moreover, consumption of pistachio as 20% of daily caloric intake increased PON1 activity by 35% and arylesterase activity by 60%, which inhibits oxidation of LDL cholesterol. They also found out that consumption of pistachio as 20% of daily caloric intake resulted in better outcomes compared with 40% of daily caloric intake. The association between hyperlipidemia and ED is originally attributed to atherosclerosis in the hypogastric-cavernosal arterial bed, with a subsequent insufficiency in penile arterial inflow.23 Impairment of endothelium-dependent relaxation in numerous vascular beds in men with hypercholesterolemia has been firmly established. These impairments have also been shown to be reversible, using lipid-lowering therapies. Another study related to this subject showed that the association between hyperlipidemia and ED is attributed to the impairment of endothelium-dependent relaxation in smooth muscle cells of corpus cavernosum by hypercholesterolemia. Wei et al. demonstrated that a high level of TC and a low level of HDL are important risk factors for ED. In this study, every mmol l–1 increase in TC was associated with a 1.32- fold increase in the risk of ED. Men with TC 4240mgdl–1 had 1.83 times the risk than did men with o180mgdl–1.29 Pinnock et al.30 showed that high cholesterol level was an independent predictor of impotence. Manning et al. found a correlation between high LDL and organic ED (68.6 vs 32.4% in the psychogenic impotence group), and a clear positive correlation between high LDL and cavernovenous insufficiency was determined. Nikoobakht et al. demonstrated that there was a significant correlation between total cholesterol and LDL with ED. According to this study, every mgdl–1 increase in plasma cholesterol and LDL levels decreased IIEF-5 scores by 0.036 and 0.035, respectively. Improvement of serum lipid profiles might be related with increase in IIEF scores in our study.
We have shown that 3-week pistachio diet applied to patients with ED resulted in a significant improvement in erectile function parameters (PCDU parameters and IIEF scores) with additional improvement in serum lipid parameters without any side effects. Further studies are needed with increased number of patients and longer follow-up evaluating the relationship between pistachio nuts and ED pathogenesis.
By M Aldemir et all.