The endurance-boosting beverage may also promote the formation of helpful “brown fat”.
Beet juice has enjoyed a surge of popularity over the last few years, largely because of evidence that its high nitrate content may improve endurance by reducing the amount of oxygen you need to sustain a given pace.
There is also evidence that the nitrate in beet juice has broader health effects, particularly on lowering blood pressure. Some researchers speculate that this is a key factor in the health-promoting effects of eating lots of leafy greens, since spinach, arugula, and other greens also have high nitrate levels.
And now, there’s yet another possible benefit. In a study published last year (hat tip to researcher Andy Jones for pointing it out on Twitter), researchers at the University of Cambridge suggest that the inorganic nitrate found in vegetables may also help turn regular white fat tissue into calorie-burning brown fat.
Brown fat has received a lot of attention over the past decade, because it’s so different from the white fat we’re more familiar with. Brown fat generates heat by burning kilojoules, and there’s evidence – in rodents, at least! – that it helps ward off weight gain and improves glucose sensitivity and insulin resistance.
Babies are born with lots of brown fat, but we tend to lose it as we age. However, under certain circumstances, conventional white fat cells can be “browned”, taking on the characteristics of brown fat. These converted cells are sometimes called beige fat. Prolonged exposure to cold is one trigger that browns fat; the Cambridge study suggests that nitrate is another.
The research involved rats and mice, and also the growth of fat cells in test tubes, so it’s hard to know at this point whether this particular pathway is relevant in humans. Still, it’s suggestive, and involves the same process of converting nitrate to nitrite and then nitric oxide within the body that has been linked to endurance gains in humans.
Another interesting wrinkle was that the transformation of white fat into brown fat due to nitrate was accelerated in low-oxygen conditions. People who are overweight often have low oxygen levels in their fat tissue, so this could be a form of defense mechanism. Perhaps endurance exercise might exert a similar stimulating effect on the fat-browning process.
Anyway, while there’s lots of research still to be done, it’s interesting to see how wide-ranging the potential effects of nitrate are. And as the authors note, it’s particularly interesting given nitrate’s checkered past (though it’s now considered a “good guy”):
“From the perspective of metabolic health and disease the small molecule has had a turbulent and mixed history. Originally considered to be biologically inactive, nitrate (and indeed nitrite) were later thought to be detrimental to human health. It was suggested that dietary nitrate may contribute to the risk of cancer development through the formation of the carcinogenic N-nitrosamines in vivo. However, mounting epidemiological and mechanistic studies have been unable to link increased dietary nitrate with an elevated risk of cancer. A World Health Organization Committee on Food Additives has since determined there was no evidence of nitrate-induced carcinogenicity.”
For now, in my hierarchy of reasons to eat lots of spinach and beets, the order remains: (1) lower blood pressure; (2) possible endurance benefits; and now I can add (3) faint possibility of enhanced brown fat stores.
