Cabbage is full of a chemical called indole-3-carbinol (I3C) which reduces your blood estrogen hormones (great if you are a guy and also great if you are a women and want to reduce the risk of breast cancer). Indole-3-carbinol is produced by the breakdown of the glucosinolate glucobrassicin, which can be found at relatively high levels in cruciferous vegetables such as broccoli, cabbage, cauliflower, brussels sprouts and kale. It is also available as a dietary supplement. Cabbage contains the antioxidants choline, beta-carotene, lutein, and zeaxanthin as well as the flavonoids kaempferol, quercetin and apigenin.

Studies show that  I3C stimulates detoxifying enzymes, helping to eliminate toxins and harmful forms of estrogen that can lead to cancer. Boiling cabbage for 10 minutes doesn't have a huge effect on I3C (80% level remains).

Diindolylmethane (DIM) is a major digestive product of indole-3 carbinol (DIM is formed naturally when I3C is broken down in the gut).  DIM has potent effects on estrogen metabolism and is able to keep the bodies estrogen balanced. In small amounts, it can both inhibit the aromatase enzyme (and prevent conversion of testosterone into estrogen) and it can act on more potent forms of estrogen and convert them into less potent forms; this conversion reduces the overall effects of estrogen in the body. Taking too much DIM at once boosts the aromatase enzyme and increases the testosterone to estrogen synthesis. Supplementing our diets with DIM can shift the production of estrogen metabolites away from dangerous 16-hydroxy in favour of beneficial 2-hydroxy metabolites. The amount of cabbage needed to be consumed is large. DIM female dosage is 100-300mg per day. To attain this amount of DIM you would need to eat 500g of cabbage, broccoli or cauliflower, Brussels sprouts and green cabbage daily. Male dosage is slightly higher.

Advice: Men should take an estradiol test (estrogen), if levels are above average then you might consider supplementing with DIM (it is widely available). This is also applicable if symptoms of estrogen are present such as man-boobs, low libido, decreased morning erections, decreased erectile function). remember that way too much DIM can have the reverse effect and boost estrogen. You can also buy I3C supplements but these should be avoided due to side-effects at high doses, I3C can also transform into many other non-DIM substances. The Bioresponse DIM Supplement looks very good, sourced from the US. A supplemental dose of approximately 100mg DIM seems a sensible option.

In a study, men took I3C 500mg daily for a week  and their oestrogen levels halved, making testosterone more effective.

Men experience a tendency to gain weight in midlife.  Rising estrogen production can result, since fat cells contain the aromatase enzyme that converts testosterone into estrogen.  Unmetabolised estrogen creates a vicious cycle resulting in further estrogen production. This occurs because fat is one source of more active aromatase enzymes (that converts testosterone to estrogen), causing further estrogen production and continuing weight gain. DIM reduces excess estrogen production associated with obesity and male aging.  Besides weight gain, another aspect of early aging in men is prostate gland enlargement. Estrogen accumulates in aging prostate glands at the same time enlargement occurs.

Nitric Oxide Booster

When you eat foods that contain natural nitrates such as cabbage, the bacteria in your tongue converts them into nitritine. Once you swallow the food, the bacteria in your gut converts the nitritines into nitric oxide. Nitric oxide is one of the main driver behind erections and without the molecule there can be no erection.

Glucosinolates tend to accumulate in higher amounts in vegetables that are organic

 Glucosinolate Content of Selected Cruciferous Vegetables
Food (raw) Serving Total Glucosinolates (mg)
Brussels sprouts ½ cup
Garden cress ½ cup
Mustard greens ½ cup, chopped
Kale 1 cup, chopped
Turnip ½ cup, cubes
Cabbage, savoy ½ cup, chopped
Watercress 1 cup, chopped
Kohlrabi ½ cup, chopped
Cabbage ½ cup, chopped
Broccoli ½ cup, chopped
Horseradish 1 tablespoon (15 g)
Cauliflower ½ cup, chopped
Bok choi (pak choi) ½ cup, chopped