Restoring Boiling-Induced Sulforaphane Depletion in Broccoli with Mustard Powder!

One of the benefits that comes from eating cruciferous vegetables like broccoli and purple cabbage is consumption of sulforaphane, a naturally occurring anticancer compound. However, do you know that boiling these vegetables for longer than 4 minutes destroys most of their sulforaphane? Besides eating these vegetables raw (I like purple cabbage raw, but not broccoli) are there any foods that when combined reduce sulforaphane destruction? Luckily, the answer is yes!

In the figure below, the white bars indicate the amount of sulforaphane present after 4, 8 or 12 minutes of boiling. Boiling broccoli for 8 minutes destroys almost 2/3 of its sulforaphane, and after 12 minutes, sulforaphane is ~75% reduced. Adding ground mustard seeds (grey bars) at a relative to broccoli concentration of 1% or 2% restored broccoli’s sulforaphane content almost completely back to initial levels after 4, 8 and 12 minutes of boiling. It’s important to note that a mustard seed concentration of 1%, relative to broccoli translates into 3 grams of mustard seed powder per 300 grams of broccoli! That’s not a lot!

broccoli sulfurophane 2

If you’re interested, please have a look at my book!

Reference

Ghawi SK, Methven L, Niranjan K. The potential to intensify sulforaphane formation in cooked broccoli (Brassica oleracea var. italica) using mustard seeds (Sinapis alba). Food Chem. 2013 Jun 1;138(2-3):1734-41.

Is Dietary Fiber Associated with Reduced Mortality?

In an earlier I post I hypothesized that gut bacteria may be involved in mechanisms that affect lifespan. Because gut bacteria ferment dietary fiber to make short chain fatty acids such as butyrate, which may be involved in processes that mediate lifespan, investigation of large-scale epidemiological studies about the association between dietary fiber intake with all-cause mortality would be a good way to test this hypothesis. While this post won’t summarize all of the studies that relate fiber intake to mortality risk, in future posts I will sequentially investigate all the studies that have examined this association.

The Dietary National Institutes of Health-AARP Diet and Health Study (Park et al. 2011) included 567,169 men and women, aged 50–71 years who provided dietary intake data for a 9-year period. Dietary intakes were assessed with a self-administered 124 item food frequency questionnaire.

Compared with the lowest dietary fiber intake (13g in men, 11g in women), death from all causes was reduced by 22%, when compared with those with the highest intake (29g in men, 26g in women). So, the answer is to eat more fiber! I should say it’s easy to get 30 grams of fiber/day. That’s pretty close to my breakfast, which includes 100g of flaxseed, 35g yacon and ~90g of medjool dates.

Which dietary component was associated with this reduced risk, fiber from grains, fruits, vegetables or beans? Relative risk (including 95% confidence intervals) for men is shown in Table 1.

Grains Fiber Mortality Table 1

In comparison with the lowest grain fiber intake, those with the highest intake had significantly reduced risk of 23%, 23%, 17%, 52% and 26% death from all causes, cardiovascular disease, cancer, infectious diseases and, respiratory diseases, respectively. In women, fiber from grains significantly reduced mortality risk for each of these categories by 17-28%, with the exception of deaths from infectious disease. So, for the Paleo types who say don’t eat whole grains, the evidence doesn’t support that idea!

In Table 2 we see that fiber from fruits was not significantly associated with reduced mortality risk for any outcome. Does that mean don’t eat fruit? No. Fruit intake is well documented to be associated with improved health, so other components besides fruit fiber are likely involved.

Fruit Fiber Mortality Table 2

What about mortality risk for fiber from vegetables (Table 3)?

Vegetable Fiber Mortality Table 3

In men, compared with the lowest vegetable fiber intake, those with the highest vegetable fiber intake had 5% and 8% significantly reduced all-cause mortality risk and, cancer deaths, respectively. In women, all-cause mortality was significanty reduced by 5%, whereas respiratory disease deaths were reduced by 28%.

The association between fiber from beans with mortality risk is shown in Table 4.

Beans Fiber Mortality Table 4

Fiber from beans was not associated with reduced mortality risk for any outcome in men, but, all-cause, CVD, cancer and infectious disease deaths were significantly reduced by 13%, 17%, 3% and 41%, respectively in women.

The take home message? Eat more fiber!

If you’re interested, please have a look at my book!

References:

Park Y, Subar AF, Hollenbeck A, Schatzkin A. Dietary fiber intake and mortality in the NIH-AARP diet and health study. Arch Intern Med. 2011 Jun 27;171(12):1061-8.