Pomegranate juice has amassed a significant body of research showing that it can improve many health markers, particularly cardiovascular, that are linked to improved erections. And Peak Testosterone readers know the maxim: "if it's good for the heart, it's good for the penis." (Thanks to Dr. Lamm for that concept.) And it is true, because if you lower blood pressure, increase nitric oxide, reverse plaque and improve lipids - all of these things will almost always help any erectile dysfunction you may be struggling with. Verifying this is a showing pomegrantate juice improved erectile function in 42 men with ED. 
This is something that I have seen confirmed on the Peak Testosterone Forum. Look at the comments of this man:
"Back to the individual labs that we call our own bodies, I have to say the POM juice has had a very noticeable positive effect for me over the last three months. In reading further on these few threads, I have added more nitrate friendly veggies multiple times per day when possible. I can't eat a whole bag of arugula like PeakT, but I try. Lately I have added 1.5g of Citrulline and grape seed extract pill (subbing in for Pycnogenol). I would agree with the one comment that if your anxiety/stress levels shoot up, or sleep is disturbed, this protocol can't overcome it with immediacy of Viagra/Cialis. However, on a regular basis, I have noticed a big difference, especially overnight and in the mornings. FYI, I drink 4-6 oz of POM brand with my breakfast." 
Pomegranate juice certainly does not work that well for everyone, but we have an ongoing poll that shows that 17% of men who tried it feel it has improved libido and erections and another 17% that feel it has helped erections but not necessarily libido.  That's about a third of the guys out there and is not a bad percentage for one juice. The research clearly backs up pomegranate's excellent erectile and arterial properties.
You do have to watch for a fading effect with pomegranate juice, i.e. it works very well for a week or two or a month or two and then fades in efficacy. Of course, one should not be relying on any one juice, food, supplement, etc. for their erectile strength: it needs to a holistic, comprehenisve program based on what I have seen. But pomegranate juice can be a nice tool in your arsensal.
Anyway, below are 7 Signs That Pomegranate Juice Will Improve Your Erectile Dysfunction:
1. Plaque Reversal (Sometimes). You put all these properties together and Pomegranate Juice becomes a near magic elixir that actually partially reversed artheriosclerosis in one study! You read that right - pomegranate juice can actually clear off some of the plaque in your arteries assuming you take it faithfully for three, six or even twelve months.  Here is a quote from Lef.org's site about this study: "Remarkably, patients drinking 1.7 oz of pomegranate juice experienced a whopping 35% reduction in the IMT score and a 44% improvement in carotid artery blood flow". IMT is the thickness between inner and middle layers of the artery.
The participants in this study were men with narrowing of the arteries (stenosis) due to arterial plaque buildup. This seems to be pomegranate juice's "sweet spot": improving arterial health in men under oxidative stress and narrowing of the arteries.
One subsequent study studied giving 8 oz of pomegranate juice to middle and senior-aged men (and women) without significant narrowing of the arteries but at moderate risk for heart disease.  It found that pomegranate juice did not actually reverse arteriosclerosis in this case but would likely slow progression in those under oxidative stress, HDL or triglyceride issues. Of course, this describes a huge subset of the population in any modern industrialized society.
So pomegranate juice may or may not reverse your arterial plaque, depending on the status of your health.
2. Increase Nitric Oxide. Are there other reasons to take pomegranate? Yes! One of the studies mentioned above  showed an average 20% drop in blood pressure. The reason for this is simple: it will significantly increase Nitric Oxide output! Yes, the same stuff that Viagra increases, pomegranate will do the same and one study showed as much as 50% in heart cells!
Of course, many supplements, fruits, vegetables and even a few grains will increase your Nitric Oxide levels. Researchers in one study looked at many of the heavy hitters in this category and concluded that Pomegranate Juice was "much more potent than Concord grape juice, blueberry juice, red wine, ascorbic acid [Vitamin C], and DL-alpha-tocopherol [Vitamin D]".  See my book The Peak Erectile Strength Diet for more information.
3. Lowers Total Cholesterol and LDL. Arterial plaque can narrow and age your arteries and the penile arteries are always affected simultaneously. One of the ways that we can help protect the lining of our arteries is by lowering our LDL and pomegrante will do this for you.  One study found little change in lipids in health individuals, so this may vary as well based on your health status.
4. Inhibits Oxidized LDL. Oxidized LDL is what does the actual damage and pomegranate juice has been shown to limit this a variety of ways.  One set of authors wrote that "most importantly, PJ treatment significantly and substantially inhibited the progression of atherosclerotic lesions. PJ inhibited atherogenic modifications of LDL, including its retention, oxidation, and aggregation." 
5. Lowers Blood Pressure. Probably the biggest and most consistent cause of erectile dysfunction is elevated blood pressure. dramatically lowers blood pressure. 
6. Fertility. There is an animal study showing that pomegranate improves sperm quality. See my page on Natural Ways to Improve Fertility for details.
7. Prostate. There is some evidence that pomegranate juice may help fight against prostate cancer. However, the primary study was funded by POM (as are some of the above studies), so many commentators feel that the more research is needed. 
DOSAGE: The "gold standard" of pomegranate juice is POM brand Pomegranate Juice. The taste and quality of POM is consistently high. Another place you can purchase it in fairly large bottles is Costco. You want between 2-4 oz per day in my opinion, but ALWAYS talk to your doctor first before taking pomegranate juice if you are on any medications. Pomegranate can alter medication and can interact with PDE5 inhibitors such as Cialis and Viagra. Several cases of priapism have occurred. Read the cautions below for more information:
CAUTION: Pomegranate Juice can potentially interfere with certain medications including statins, calcium channel blockers, immunosuppressants, antiarrhythmics and others. The issue is that Pomegranate Juice (and Grapefruit Juice) affect the P450 3A4 enzyme system within the liver, i.e. absorption of certain drugs can be affected. One journal documented a serious muscle tissue breakdown case that occurred from Pomegranate Juice interacting with a statin.  Please consult with your doctor or pharmacist for possible interactions. In addition, please read my link on The Potential Side Effects of Pomegranate Juice : there was an animal study showing it increase the risk of Parkinson's.
CAUTION: #2 Again, talk to your doctor if you are on any medications: there are three reported cases of priapism occurring in men simultaneously taking Viagra.  Again, pomegranate juice is very powerful.
1) Clin Nutr. 2004 Jun;23(3):423-33, ""Pomegranate juice consumption for 3 years by patients with carotid artery stenosis reduces common carotid intima-media thickness, blood pressure and LDL oxidation""
2) International Journal of Impotence Research, Nov/Dec 2007,19(6):564 567
3) Nitric Oxide, 2006 Sep, 15(2):93-102
4) Intl J for Vitamin and Nutrition Res, May 2006, 76(3):147-151
5) The J of Nutritional Biochem, 16(9):570-576, Sep 2005, B. Fuhrman, et. al., "Pomegranate juice inhibits oxidized LDL uptake and cholesterol biosynthesis in macrophages"
6) Clin Nutr 2004;23(3):423-33
7) Amer J of Cardiology, 98(5):705-706, Sep 1 2006, "Rhabdomyolysis Associated With Pomegranate Juice Consumption", Alexey V. Sorokin, et. al.
8) The American Journal of Cardiology, Oct2009, 104(7):936-942, "Effects of Consumption of Pomegranate Juice on Carotid Intima Media Thickness in Men and Women at Moderate Risk for Coronary Heart Disease"
10) Am J Clin Nutr, 2000, 71:1062 76., "Pomegranate juice consumption reduces oxidative stress, atherogenic modifications to LDL, and platelet aggregation: studies in humans and in atherosclerotic apolipoprotein E deficient mice"