Close to 2000 years ago, Cato the Elder, a Roman general, senator and historian, professed that cabbage, eaten raw with vinegar or cooked with oil or fat, could cure anything from an ear infection to cancer. I can’t quite provide you with evidence-backed information to support his claims regarding ear infections, however you only have to search the scientific database Pubmed to reveal literally thousands of peer-reviewed papers supporting the role of the cruciferous family (of which cabbage is a part) in reducing the risk of cardiovascular disease, stroke, diabetes and dying prematurely from all causes (bar accidental death). Other members of this family include cauliflower, broccoli, brussels sprouts and broccoli sprouts.
A study that divided people up in categories of cruciferous vegetable consumption found that the top 20 per cent of consumers reduced their risk of all-cause mortality by 22 per cent compared to those who ate the lowest amount. Other studies have found men eating between three-five servings of cruciferous vegetables per week had a 40 per cent decrease in prostate cancer risk compared to men who ate less than one serve of these vegetables per week, and men who ate two or more half cups of broccoli per week had a 44 per cent lower risk of bladder cancer compared to men who ate less than one serve per week. Multiple studies have found that women who eat at least one serving of cruciferous vegetables per week had between 17-50 per cent decreased risk of breast cancer. The variation in risk reduction may have to do with the preparation of the vegetables and whether they were fresh or frozen, which affects the bioavailability of the active compounds in these vegetables. Blood glucose, triglycerides, and oxidised LDL cholesterol all fell by between 13-20 per cent when people with type 2 diabetes consumed broccoli sprouts each day for four weeks, highlighting the anti-atherosclerotic effect of this vegetable. It’s safe to say that there is something in cruciferous vegetables that is impacting on disease progression in the body, and though we cannot determine cause and effect, we can investigate whether there is a plausible mechanism from which broccoli could be having these effects. And that appears to be isothiocyanates.
Isothiocyanates
Isothiocyanates are produced by compounds known as glucosinolates that are present in cruciferous vegetables. The glucosinolates are activated by an enzyme called myrosinase when the cruciferous vegetable is chopped, crushed or chewed, but deactivated when subjected to long periods of high temperatures, such as boiling water. Sulfurophane is the glucosinolate that stands out from the rest as the most potent and has undergone many trials to support its anti-inflammatory and anti-carcinogenic properties.
The favourable effects on health
Isothiocyanates activate phase 2 detoxification enzymes in our body via something called the Nuclear factor (erythroid-derived 2)-like 2 (or Nrf 2) pathway, and sulfurophane is the most potent naturally occurring inducer of this. Nrf 2 controls hundreds of genes, binding to them and either initiating or inhibiting their action. This includes deactivating our inflammatory genes and upregulating anti-inflammatory genes involved in diabetes and cardiovascular disease progression. The detoxification pathways, as the name suggests, are responsible for neutralising potentially harmful compounds and removing them from our system. Phase 2 detoxification enzymes — triggered by sulfurophane — can inactivate pro-carcinogenic compounds by transforming them into water-soluble compounds which are less reactive and able to be excreted via urine or bile. Isothiocyanates, particularly sulfurophane, can also reduce DNA damage by reducing inflammation and reactive oxidative species. Studies have found that cruciferous vegetables aid in the excretion of harmful chemicals (such as benzene from cigarette smoke and air pollution) and decrease DNA damage. Interestingly, associative studies looking particularly at smokers found those who consumed at least 4.5 serves of raw cruciferous vegetables per month had a 55 per cent reduction in lung cancer risk compared to those who ate less than 2.5 serves per month.
Sulfurophane is able to cross the blood-brain barrier and as such, exert positive effects on the inflammatory processes in the brain that are involved in the progression of neurological disorders such as Alzheimer’s, ADHD and depression. Cellular studies have found it to reduce reactive oxidative species (ROS), inflammatory enzymes and beta-amyloid plaques in the brain, all of which are associated with Alzheimer’s disease. It also increases the expression of a major antioxidant enzyme, superoxide dismutase (SOD). Mice models of depression have found a similar effect, with sulfurophane reducing the production of lipopolysaccharide, an endotoxin associated with brain inflammation. Perhaps even more interesting, the administration of food containing glucoraphanin (the precursor to sulfurophane) in juvenile mice had lasting effects once they reached adulthood. There was a reduction in social avoidance behaviour and reduced preference for sucrose in mice undergoing repeated stress tests, two characteristics indicative of depression seen in mice facing the same tests who were not administered the glucoraphanin.
The best dose of sulfurophane
The most potent source of sulfurophane is broccoli sprouts, and they are easy and inexpensive to grow at home how to grow broccoli sprouts and add to smoothies, salads or eat on the side. Interestingly, freezing the sprouts once ready will increase the sulfurophane content three-fold. Outside of this, regularly consuming cruciferous vegetables exerts benefits that shouldn't be overlooked, as the research clearly indicates. While myrosinase is deactivated at high heats, adding mustard seed powder to cooked vegetables before serving will help reactivate it and enhance the amount of sulfurophane present.
See here for how to grow broccoli sprouts
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