Thread by @Luke_Bell_1987

There's been a story in a UK tabloid (that I won't name), and @BBCRadio4 of all places; that #rocket #salad causes #cancer due to high levels of #nitrates in the leaves. Here's my take, and what's wrong with the thinking behind it.

A thread.

1/12

It's true, #rocket #leaves are hyperaccumulators of #nitrates ; this isn't anything new. It's been known for a long time. Other crops with high nitrate content include #spinach and #watercress

2/12

Nitrate content varies according to where the #crop is grown, and is closely tied to the soil #plants are grown in, and the amount of #light they receive. Rocket leaves grown in #winter have higher nitrate content than those grown in #summer

3/12

The #EU introduced in regulation No. 1881/2006 to impose 'limits' on nitrate in rocket. These values were completely arbitrary, and not based on any #scientific #clinical data. The 'limits' for spinach, are half that of rocket, yet both can contain similar amounts.

4/12

Nitrates are thought to react with acid in the stomach to produce nitrosamines. It is these products which are thought to be #carcinogenic

No human studies have ever conclusively proved this to be the case.

5/12

The body of #evidence arguably lies with the opposite #hypothesis ; that nitrate is beneficial for human #health

E.g. Some studies related to #sports #nutrition have found beneficial effects in athletes who consume nitrate-rich #vegetables

onlinelibrary.wiley.com/doi/abs/10.111…

6/12

There are also noted benefits for blood pressure:

academic.oup.com/jn/article/146…

This study specifically used rocket

7/12

There are even reported beneficial effects for smokers who consume more nitrate:

sciencedirect.com/science/articl…

8/12

The tabloid #article also completely missed the fact that rocket produces other #phytochemicals that have been linked with positive health effects, such as #isothiocyanates and #flavonols

9/12

My own and @cwagstaff 's research has shown that the isothiocyanate #sulforaphane (linked with anti-cancer effects; specifically prostate cancer) is stable or even increases in rocket leaves #postharvest

sciencedirect.com/science/articl…

10/12

Rocket also contains high concentrations of #polyphenols. Work by @ggkuhnle et al. @UniRdg_FNS has shown that these reduce the formation of carcinogenic nitrosamine compounds, and promote formation of anti-cancer nitroso-polyphenol derivatives:

sciencedirect.com/science/articl…

11/12

Generally, #scientists and #nutritionists agree that the benefits of eating #vegetables and #salads far outweigh any small risks

12/12