Grain-bashing is a popular pastime right now in the blogosphere, but make no mistake: whole grains - and I emphasize whole - are good for your penis and erections. Grains are excoriated for being a relatively new invention of modern man and, therefore, neither truly natural or healthy. Supposedly, they are packed with chemicals that block vitamin and mineral absorption, raise insulin and are the Freddie Kruegar of the dietary world.
But the truth is that these beliefs are strictly "religious" in nature and are simply unfounded for whole grains. Study after study has not only exonerated whole grains but shown that grain-based diets are very high performers and deserve nothing but the utmost respect from the nutritional community. Don't listen to the grain-haters: your penis will thank you.
So let's go through the accusations one by one. First of all, grains supposedly destroy your sugar and insulin metabolism according to the Paleolithic proponents. Well, one study looked at a diet high in unrefined carbohydrates, i.e. grains, and found that it actually improved insulin sensitivity. In fact, the title of the study is revealing: "A Mediterranean and a high-carbohydrate diet improve glucose metabolism in healthy young persons".  This undoubtedly shocked the Low Carb blogophiles: glucose metabolism AND insulin sensitivity is actually improved by lots of carbohyrdates.
NOTE: Did you know that quinoa, a grain from South America growing steadily in populariy, has a perfect protein just like an egg? It's also as easy to fast and cook as rice.
CAUTION: I am not a big fan of modern wheat. Along with soy and corn, it has been highly genetically engineered: read my Review of Wheat Belly for some of the negative properties of modern wheat.
Remember that a Mediterranean Diet also has significant unrefined carbs. The conclusion of the researchers was that substituting either unrefined carbs or monounsaturated fats for saturated fats improved insulin sensitivity. This is a very unappealing concept to the carnivore-or-die crowd, who want to believe lots of carbs will overwhelm our digestive and metabolic systems. And don't forget that Metabolic Syndrome is very hard on the penis and a leading cause for erectile dysfunction.
Their reasoning goes like this: 1) high carbs are broken down into high levels of blood glucose, 2) high levels of blood glucose require high levels of insulin to be produced, 3) years of high insulin levels eventually exhaust the body and 4) insulin resitance and diabetes follow shortly thereafter. But all of these are completely unfounded myths.
The fact is that grains do the opposite of what all the naysayers say: grains actually are diabetes-preventative. For example, one major study found that a higher intake of fruits, fish and grains was actually associated with a lower risk of diabetes.  Another major study, in this case of women, said it clearly: "Whole grain intake is inversely associated with risk of type 2 diabetes, and this association is stronger for bran than for germ. Findings from prospective cohort studies consistently support increasing whole grain consumption for the prevention of type 2 diabetes". 
Furthermore, researchers recently found out that the high glutamic acid, the primary amino acid plant protein, content in plant products, such as grains in particular, led to a drop in blood pressure.  A later study found that those who ate a significant amount of whole grains, over about 46 grams/day, were 19% less likely to develop hypertension.  And, as Peak Testosterone readers well know, a drop in blood pressure almost always means expanding arteries and expanding arteries is what allows blood flow into the penile chambers. Remember also that hypertension is bad for the penis and erections and is a major cause of erectile dysfunction. This may explain some of the powers of the Ornish, DASH and Mediterranean Diets to lower blood pressure.
Another criticism of grains is that they are nutritional weaklings. In other words, low carb folks basically often claim that eating fruits and vegetables are much higher in value than grains and so why not stick to them instead? Again, science has found the opposite. One 2009 study by the American Chemical Society found that grains had as many antioxidants as fruits and vegetables.  Again, this may be yet another explanation for why the Mediterranean and Low Fat Diets have done so well in the studies.
Many of the grains also directly boost Nitric Oxide, a fact that I cover in more detail in my Peak Erectile Strength Diet program. Boosting Nitric Oxide, of course, is what Viagra and Cialis are all about and will help your penis achieve its maximum hardness factor.
The truth is that grains prime your system with vitamins, mineral and phytochemicals and do it without destroying your metabolic health. There simply are few better all around foods for your general and sexual health. Grains are penis protective - it's that simple.
ln fact, the poster children for grains are the Ikarians, residents of a Greek Island where one in three residents live to be 90! (This is in market contrast with America, with its expensive health care system, where about 1 in 9 do.) One of their secrets is a Mediterranean Diet, with lots of grains, fruits, vegetables and olive oil. Oh, and AARP reports that most Ikarians over 90 are probably sexually active, which means that grains can't be too bad for the ol' penis, eh?
1) Diabetologia, 2001, 44(11): 2038-2043
2) Ann Intern Med, 2002, 136(3):201-209
3) Pub Library of Science, Aug 2007, Med 4(8): e261
4) Circulation, Submitted on Nov 27 2008, Accepted May 15 2009, "Glutamic Acid, the Main Dietary Amino Acid, and Blood Pressure. The INTERMAP Study (International Collaborative Study of Macronutrients, Micronutrients and Blood Pressure"
5) American Chemical Society (2009, August 19). Whole Grain Cereals, Popcorn Rich In Antioxidants, Not Just Fiber, New Research
6) Am J Clin Nutr, 2009, 90:493-498, "Whole grains and incident hypertension in men"