Exposure to potentially toxic substances in our food and water, or in the air we breathe both indoors and outdoors, exposure to allergy-triggering substances, poor general health, dietary deficiencies, use of prescription and over-the-counter medications, and other lifestyle practices can result in a level of danger to our bodies that prompts our inflammatory system to work in overdrive on a 24/7 basis. Researchers often refer to this phenomenon as "chronic inflammation." Often contributing to this level of danger is a weakened detoxification ability in our body. If our liver, skin, and other organ systems cannot keep up with and detoxify the number of potential toxins that we encounter, too many potential toxins remain at large throughout our body. Once again, the result is a level of risk that prompts chronic inflammation.
On a more temporary, short-term basis, inflammation is part of good health. Whether physical or chemical in nature, whenever our body detects a wound, it typically responds by trying to heal it with an inflammatory response. That process is healthy, so long as it is not constant and uninterrupted. But unlike the helpful inflammation that takes place we get a simple cut or bruise, chronic inflammation—when it becomes a standard feature of our metabolism—is incompatible with good health. When our bodies are overwhelmed day in and day out with chronic inflammation, many other metabolic balances can get thrown out of kilter, including the balance in our oxygen metabolism. An unwanted imbalance starts to occur in which too many overly reactive, oxygen-containing molecules are formed. This condition is called oxidative stress. The increased presence of these overly reactive molecules can do damage to many parts of our cells, including their genetic material (and especially their deoxyribonucleic acid, or DNA). Over time, the constant and cumulative DNA damage inside our cells can pose a major risk factor for conversion of healthy cells into cancerous ones.
It's equally possible for this sequence of events to start not with chronic, excessive inflammation, but with chronic oxidative stress. Over time, when overly reactive oxygen-containing molecules cause damage to DNA and other cell structures, our body reads this situation as being highly dangerous and it initiates an inflammatory response to try and reduce the threat posed by the oxidative stress. In either case, we end up with a combination of inadequate detoxification of toxic substances, chronic inflammation and oxidative stress that puts us at greater risk for developing cancer.
In a way that might be unique among foods, the nutrients found in cruciferous vegetables (for example, broccoli or kale) are able to change this set of connections between inflammation, oxidative stress, detox and cancer. In fact, it would be fair to describe cruciferous vegetables as containing anti-inflammatory nutrients, antioxidant nutrients, detox-support nutrients, and anti-cancer nutrients as well.