You’ve likely heard that broccoli and its “cruciferous” cousins can help prevent cancer.
Vegetables in the cruciferous family get their name from the cross-shaped indentations in their buds.
Those cruciferous cousins include cabbage, collards, cauliflower, kale, cress, mustard greens, turnips, rutabaga, horseradish, wasabi, arugula, bok choy, and Brussels sprouts.
The anti-cancer power of this family of vegetables comes primarily from chemicals called glucosinolates and indoles.
When we cook, chew, and digest cruciferous vegetables, their glucosinolates break down into compounds that display anti-cancer effects.
The most promising of these anticancer allies are indole-3-carbinol and sulforaphane, which possess these helpful properties:
The evidence that cruciferous vegetables may reduce the risk for breast, colon, lung, and prostate cancers comes from population studies.
That epidemiological evidence is mixed, but many lab and animal studies find that they should help discourage the development and spread of common cancers.
And research published in the past decade suggests that genetic variations — called polymorphisms — may govern the ability of anti-cancer compounds in cruciferous vegetables to reduce the risks for lung and colorectal cancers.
Gene variations may also affect the power of cruciferous vegetables to reduce each individual person’s risk for breast, prostate, or other cancers.
Although the evidence is strong enough that the NCI recommends eating cruciferous vegetables — and all other kinds – we’re not here to talk about their anti-cancer potential.
Instead, new research shows that indoles such as the indole-3-carbinol in cruciferous vegetables extends the “healthspan” of experimental worms, flies, and rodents.
Healthspan versus lifespan
Measures to lengthen life — also called “lifespan” — get all the attention.
But what good is a longer life if all or most of those extended years are marked by pain and/or disability?
A newer concept called “healthspan” is rapidly gaining ground in biomedical research, given the unpredictable — possibly very low — value of simply adding more years.
The term healthspan refers to the portion of life in which the body is mostly or fully functional and largely disease-free.
A person’s healthspan depends on their genes, diet, and lifestyle, including their exercise or activity levels.
Cruciferous veggies may extend healthspan
Scientists from Atlanta recently reported that indole may help extend healthspan.
Indole is the chemical at the center of the indole compounds in cruciferous vegetables, such as indole-3-carbinol.
A team based at the Emory University School of Medicine — led by professor Daniel Kalman, Ph.D. — has been studying the health effects of indole in worms, fruit flies, and mammals.
These creatures’ own gut microbes routinely produce indole, provided the right ones are present, including a common type of E. coli that doesn’t cause disease.
Those same microbial processes occur in the human gut, where friendly microbes — including friendly forms of E. coli — convert the glucosinolates in cruciferous vegetables into indole.
In other words, the results of these animal experiments should translate to humans — although to be certain, they will need to be replicated in people.
Emory University experiments link indoles to extended healthspan
The Emory researchers fed worms the type of friendly E. coli bacteria that produce indole.
They then compared those worms with worms fed a type of E. coli that cannot produce indole (Sonowal R et al. 2017).
As they age, older worms spend less time moving around, can't swallow as well and are more sensitive to stressors.
Indole didn't extend the worms’ lifespan, but it markedly lengthened the time worms were mobile after the age of 15 days, and increased their swallowing strength and resistance to heat stress.
In addition, worms usually stop reproduction at the age of five days, but the indole produced by their gut microbes more than doubled their reproductive span, allowing them to remain fertile up to 12 days.
Indole had similar effects on mobility and resistance to heat in Drosophila fruit flies, and produced a comparable pattern in mice.
The researchers also analyzed the patterns of gene activity affected by indole. Interestingly, the genes regulated by indoles were distinct from other worm genes previously linked to longevity.
To see whether these effects would extend the mammals, the Emory team treated mice with antibiotics to eliminate the existing gut microbes, and then re-colonized them with either normal E. coli, or with bacteria that cannot produce indole.
In very old mice (28 months), the gut-produced indole helped animals maintain their weight, mobility and activity levels.
And, in younger mice, indoles extended their survival after exposure to lethal levels of radiation.
“It's like the Picture of Dorian Gray, in terms of the genes involved,” Kalman said. “Indole makes old animals look more like the young ones.”
The Emory teams speculated that indole produced in our guts may help keep the intestinal barrier intact — thereby barring undesirable compounds from the bloodstream — and/or by limiting system-wide inflammation, which promotes aging and a wide range of diseases and infirmities.
Professor Kalman's team wants to discover whether having a mix of gut microbes that fails to produce much indole may contribute to frailty, and whether dietary indole might slow aging and discourage disease.
“Indole is such an ancient messenger,” Kalman said. “It’s how plants steer their growth, how bacteria talk to each other, and how plants and bacteria ‘talk’ with our bodies and ensure proper homeostasis [stability] within our immune system. It’s perhaps not so surprising that this molecule helps maintain our vitality.”
Buckwheat may be another healthspan-booster
Last year, Vanderbilt University researchers reported that a compound found in buckwheat seeds extends the lifespan of worms (Nguyen TT et al. 2016).
Their study involved the same worm employed by the Emory University team — C. elegans — which is commonly used in studies of basic biological processes essential to humans.
Worms fed salicylamine — a compound in buckwheat that inactivates damaging molecules called isoketals — lived longer healthy lives compared to worms not receiving the compound.
(Isoketals are formed during normal cell metabolism, and disrupt the function of proteins and DNA. Levels of proteins damaged by isoketals are higher in people with atherosclerosis, Alzheimer’s disease, hypertension, and end-stage kidney disease.)
The Vanderbilt team found that salicylamine lengthened worms’ median lifespan from 16 to 25 days.
Critically, they also found that the longer-lived worms remained healthy, so salicylamine also appears to lengthen healthspan.
The Vanderbilt findings from 2016 support the idea that oxidative (free radical) damage produced by compounds such as isoketals contributes to aging-related tissue damage and death.
“There’s a notion that we’re slowly oxidizing ourselves to death,” said study co-author L. Jackson Roberts, M.D. “If we could overcome that, we predict we would have a longer lifespan.”
Roberts and his colleagues previously identified isoketals as byproducts of the oxidation of fatty acids and other lipids. "With every breath, we’re generating molecules that can potentially damage us,” said study leader Thuy Nguyen, Ph.D.
In previous studies, the researchers discovered that dietary salicylamine prevented age-related memory deficits in mice suffering from a brain disease similar to Alzheimer’s.
Dr. Roberts and his colleagues had also discovered that salicylamine “scavenges” or neutralizes isoketals and prevents them from damaging proteins.
He's convinced that salicylamine can prevent oxidative (free radical) damage and possibly extend people’s healthspans, and Vanderbilt faculty member Naji Abumrad, M.D., plans to market salicylamine as a dietary supplement.
Most lifespan studies have used genetic tools or altered developmental pathways to achieve their effects.
In contrast, as Dr. Nguyen noted, we can get salicylamine from our diets — especially from buckwheat, whose uncommon health attributes we’ll review.
Buckwheat: An underrecognized superfood
Even though its name includes “wheat”, buckwheat is not a grain.
Instead, buckwheat is the seed of a flowering plant, and it contains no gluten.
Buckwheat is also rich in polyphenol-type antioxidants such as rutin and quercetin.
Those antioxidants also occur in many fruits and vegetables, but buckwheat contains an overlooked category called “bound” antioxidants, which may be equally important
The bound antioxidants in buckwheat include glutathione and superoxide dismutase, which survive cooking and are released by our gut microbes during digestion.
Buckwheat (like beans) is rich in “resistant” starch, which stabilizes blood sugar levels after meals, aids weight loss, curbs food cravings, and thereby may reduce the risk for diabetes.
As Chinese researchers wrote last year, “… buckwheats possess antitumor, anti-oxidant, anti-inflammatory, hepato-protective, anti-diabetic activities, etc. All reported data lead us to conclude that Fagopyrum buckwheats have convincing medicinal potential.” (Jing R et al. 2016)
Eastern Europeans commonly enjoy the toasted, steamed groats known as kasha, while buckwheat is the key ingredient in Japanese soba noodles.
Soba noodles make a delicious, gluten-free alternative to wheat pasta, and many gluten-avoiders find they prefer soba to bean- or rice-based pasta.