"Know thyself" is a central principle of philosophy that goes back as far as Socrates. "He that knoweth or supplements, it is positively correlated with increasing levels. Here is a sample study among others. Zinc A zinc deficiency can adversely affect your levels. Studies have shown that zinc supplementation in men with zinc deficiency has increased their levels. Zinc supplements, oysters, beef, pork, crab and fortified cereals provide excellent sources of this mineral. Be careful not to consume too much zinc, because toxicity is possible. Nuts and legumes These foods contain high levels of D aspartic acid that promotes the production of in humans. In addition to soy, lentils and almonds, salmon, shrimp, beef .