Natural herbs and foods are the source of many therapies for impotence. Some of the herbs that increase erection and sexual power have been known and used for centuries. However, as a general rule, in order to gain benefit from a particular herb or food, one should habitually consume it over long periods rather than a short course, since the active ingredient is usually diluted as it is present in the herb among many more organic materials. This is why medications have been invented based on those herbs, concentrating the active ingredient extracted from a larger volume of herbs in a small pill, that functions after consumption for a shorter term.

While most herbs enhance sexual power indirectly via increasing general well being, some of them act directly by enhancing erection or sexual desire. 

A final fact is that the effect of most of the available herbs on erectile function is not well studied, cannot be confirmed medically, and is based on word of mouth, myths, and cultural habits, unlike prescription drugs which go through a phase of animal studies then through another phase of human clinical trials (on volunteers), so that their efficacy and more importantly their safety can be confirmed.

Honey and Royal Jelly:

Honey is an enormous source of energy, vitamins and anti-oxidants, all of which are essential for general well being, and for enhancing sexual power, libido and erection.

Royal Jelly is the most pure and concentrated form of honey, upon which the queen bees feed. Royal jelly is famous for enhancing bodily functions and sexual function. In addition to the natural form, it is available as pills and capsules with high concentrations combined in some cases with vitamins and minerals.

Sea food:

Most kinds of marine creatures are known for their aphrodisiac (desire enhancing) effect.

Ginseng

Ginseng used worldwide for promoting general health, increasing longevity and vigor, enhancing memory and concentration. It is also well known for promoting erection and sexual desire. Its use started in the Far East, centuries ago.

It is available in different forms as tablets and syrups, in addition to the naturally occurring root.

Yohimbe

Is a herb that has been medically tested and approved for its efficacy and safety in promoting erection. Its active ingredient "yohimbine" acts on the brain to lower the threshold for erection. Thus, minimal impulses and stimulants are enough to induce a rigid erection.

Unfortunately, it is known to result in hypertension in some cases, and has to be consumed under medical supervision.

Yohimbe is available in many prescription forms that enable controlling the dose, effect and side effect.  

The list of sexual health promoting herbs is endless, and differs from one country to the other. The above-listed are nearly the only that are approved for medical practice. Otherwise, efficacy and safety of the herb or food cannot be confirmed.