Inhaltsstoff-Glossar

Sulforaphane

What Is Sulforaphane?

Sulforaphane is a mustard oil compound found in broccoli and cauliflower. It protects plants against herbivores and, due to its pungent smell and taste, also acts as a deterrent to humans. Numerous mechanistic studies using cell cultures and animal models have demonstrated the antioxidant, anti-carcinogenic, and anti-inflammatory properties of sulforaphane. However, because only a limited number of clinical studies have been conducted in humans, direct evidence of its effects in people is still lacking. Nevertheless, sulforaphane is widely regarded as a promising dietary supplement for reducing the risk of chronic diseases.

Where Does Sulforaphane Naturally Occur?

Sulforaphane is a mustard oil compound produced by certain plants to defend themselves against herbivores. The plant stores sulforaphane safely in an inactive form within its tissues, ensuring that it is released in its active and aggressive form only when the plant is damaged by predators. In intact cells, it is present as an inactive glucosinolate bound to a sugar molecule.

The enzyme myrosinase separates sulforaphane from the sugar, allowing it to carry out its protective function against invading organisms. This enzyme is stored in a different compartment of the plant cell. When the plant tissue is damaged, the glucosinolate and myrosinase come into contact as intended. The enzyme releases sulforaphane, which then acts as a mustard oil compound to defend the plant against attackers.

Plants cleverly store sulforaphane in its sugar-bound form within cellular compartments. For humans, this means that the bioavailability of sulforaphane from cruciferous vegetables depends greatly on how they are prepared. Sulforaphane is biologically active only after it has been released from its sugar molecule. Therefore, the enzyme myrosinase must be given sufficient time to act before broccoli, cauliflower, or radish are consumed. Simply cooking the vegetables to break down their cell walls is not an ideal solution because heat rapidly inactivates myrosinase.

To improve sulforaphane absorption, vegetables can be finely chopped and left to rest before cooking. Alternatively, broccoli sprouts—which contain much higher concentrations of sulforaphane—can be consumed. Per 100 g of dry weight, broccoli contains approximately 40–170 mg of sulforaphane, whereas broccoli sprouts contain more than 1,000 mg, roughly ten times as much. Dietary supplements provide a convenient way to consume sulforaphane in standardized doses.

What Is the Primary Function of Sulforaphane in the Body?

Sulforaphane supports the body's antioxidant defense system. Many antioxidant compounds, such as vitamin C and vitamin E, act as direct free radical scavengers by neutralizing reactive oxygen species (ROS). Sulforaphane, however, works differently: it activates endogenous antioxidant systems, including glutathione, which subsequently neutralize ROS. For this reason, experts describe sulforaphane as an indirect antioxidant.

Glutathione not only functions as an antioxidant but also plays an important role in detoxification by supporting the transformation of harmful substances within the body, thereby facilitating their elimination through the kidneys. Sulforaphane therefore contributes to the removal of unwanted and potentially harmful compounds not only by activating glutathione but also by stimulating the activity of the proteasome.

The proteasome serves as the cell's waste disposal system. It breaks down proteins that are damaged, misfolded, or no longer functional. Longevity researchers believe that the accumulation of such dysfunctional cellular waste contributes to the aging process. The build-up of damaged or misfolded proteins is considered a hallmark of cellular aging and is associated with increased inflammation and a higher risk of chronic diseases. By activating the proteasome, sulforaphane influences these processes. In addition, studies using cell cultures and rodents have shown that sulforaphane activates sirtuins, a family of genes involved in the regulation of longevity.

What Are the Benefits of Sulforaphane Supplementation?

In several cell culture and animal studies, sulforaphane has demonstrated anti-carcinogenic properties. For example, it inhibited the growth of breast cancer cells, which researchers attributed to its ability to disrupt microtubules that cancer cells require for proliferation.

Epidemiological studies have associated diets rich in cruciferous vegetables with a reduced risk of prostate cancer. Sulforaphane has been proposed as one of the mechanistic explanations for this observation. Both mechanistic and clinical studies in humans have shown that sulforaphane reduces the activity of histone deacetylases, enzymes that play an important role in the growth of prostate cancer cells.

Inflammation and oxidative stress contribute to the development of arterial calcification, commonly known as atherosclerosis. Sulforaphane may help counteract these risk factors for cardiovascular diseases such as stroke and heart attack. Several studies have demonstrated potential benefits of sulforaphane with regard to antioxidant capacity and inflammatory markers. A meta-analysis in rodents confirmed that sulforaphane can reduce body weight, cholesterol, and triglyceride levels. Additional studies investigating sulforaphane in mouse models of hypertension and diabetes further support the hypothesis that this compound may help prevent cardiovascular disease.

The accumulation of dysfunctional or misfolded proteins has been linked to various chronic diseases whose incidence increases with age. Sulforaphane activates the proteasome and promotes the breakdown of this cellular waste. It is therefore hypothesized to contribute to a longer healthspan and potentially increased longevity. However, findings from cell culture and animal studies are not sufficient to demonstrate comparable effects in humans. Accordingly, the authors of one comprehensive review concluded that "further intervention studies are required (...) to reach more robust conclusions."

Dietary supplements provide doses equivalent to consuming approximately 500–1,000 g of broccoli or several grams of freshly harvested broccoli sprouts. Because the amount of biologically active sulforaphane obtained from cruciferous vegetables is highly variable, supplementation represents an efficient and standardized method of intake.