Broccoli - Be Careful, Plants are Tricky
Plants can have nutrients, but they also contain anti-nutrients. This makes it hard to assess whether you are better or worse off eating them, and is why they are inferior to animal sourced foods. Broccoli is no exception.
Earlier, I took mainstream nutritionist Tim Crowe to task for his debating methods over the issue of whether broccoli is good for you. I raised the question of oxalate content as one reason to question this claim.
Oxalates are an example of an anti-nutrient. On the other side of the scale, however, are glucosinolates. These are central to the argument that eating broccoli is a good idea. I found this on the topic,
'Broccoli (Brassica oleracea var. italica), a member of Cruciferae, is an important vegetable containing high concentrations of various nutritive and functional molecules especially the anticarcinogenic glucosinolates'. https://www.sciencedirect.com/topics/medicine-and-dentistry/broccoli
Note that my source here is a book on 'Medicinal Plants'. If you remember, my position is that plants are medicine, not food. So if broccoli can be used as part of a treatment for cancer I don't have a problem with that at all, its good news. That doesn't mean we should eat it as part of our normal diet, these are two separate things.
So what are glucosinolates ? I found this,
'Glucosinolates are biologically active compounds found in the Brassicaceae family of plants, including broccoli, cabbage, cauliflower, rapeseed, mustard, and horseradish. Recent studies have shown beneficial effects of glucosinolates, including regulatory functions in inflammation, stress response, phase I metabolism, and antioxidant activities, as well as direct antimicrobial properties'. https://www.sciencedirect.com/topics/pharmacology-toxicology-and-pharmaceutical-science/glucosinolate
Inside the body, glucosinolates undergo hydrolisis, whose products, 'especially isothiocyanates (e.g., sulforaphane), are considered to be responsible for the protective, anticarcinogenic effects of a cruciferous-rich diet'. (ibid)
Sulforaphane I've heard of, Rhonda Patrick makes much of it. I'm not yet in a position to judge how valuable it might be.
So far so good, eat broccoli, prevent cancer, it might taste disgusting but that seems a fair trade off.
Not so fast, because that is not all you are getting. Lets read further from the same source,
'However, livestock species fed rations with high glucosinolates may exhibit adverse effects, including reduced feed intake and growth, gastrointestinal irritation, goiter, anemia, and hepatic and renal lesions. High sulfur can be associated with trace mineral deficiencies and polioencephalomalacia. Therefore, although a good source of nutrition, it is best to avoid overfeeding Brassicaceae'.
Makes sense, when dealing with medicines dose is always important.
'Some of the hydrolysis products (goitrin, thiocyanate ion, several isothiocyanates, and nitriles) may have antinutritional or toxic effects;' ... 'These adverse and beneficial effects are highly dose-dependent and the physiological range is relatively narrow'.
So what is the right dose for humans, and do the benefits outweigh the costs ?
'The large number of glucosinolates, the plethora of hydrolysis products possessing differing biological activities, and the dose dependence of the effects observed make research in this area both challenging and complex'.
Remember, we started this discussion out with a piece by Tim Crowe taking the piss out of the idea that broccoli might not be so clear cut. Doesn't look so open and shut now, does it ?
In fact the difficulty over glucosinolates has led to confusing and conflicting hybridisation strategies among plant growers - do we want more or less of them ? It seems growers have gone both ways, so what you are actually getting in your supermarket hunt for plants and seeds with 'anti-carcinogenic' glucosinolates is anyone's guess.
'Thus, plant-breeding strategies that concentrated solely on reducing the glucosinolate content of rapeseed for nutritional benefits succeeded in producing very low (‘zero’) glucosinolate varieties that were more nutritious but these required a significantly increased expenditure for crop protection. On the other hand, pest-resistant crop cultivars that contain high amounts of individual glucosinolates may have unacceptable sensory characteristics and may, possibly, also exhibit antinutritional properties'.
This introduces another element - pest resistance. So if you go with the more nutritious option, stated here as the low glucosinolate one, then you have to apply more chemicals to keep the pests away. Nice.
People, plants like these are nasty, let the insects have them.