|There are two things you have to keep in mind, when you want to reap the benefits: Timing and dosage. With the currently available nitrate-based / -containing supplements, and both were probably off for the average customer.|
The use of the natural alternative, i.e. beet root juice, on the other hand, is complicated, because there is little information on how much nitrate you need and how much of it can be found in the average beet from the supermarket.
Luckily Lee J. Wiley et al. must have realized that as well and set out to characterize the plasma NO3 and NO2 pharmacokinetics and the changes in BP after ingestion of three different quantities of NO3-rich beet root juices, as well as the corresponding dose-response relationship between beet root juice and NO3 intake and the physiological responses to exercise. To this ends, the researchers administered different amounts of a beet root concentrate, i.e.4.2, 8.4, and 16.8 mmol from 70, 140, and 280 ml of Beet It, and measure the plasma NO3 and NO2 response, and the blood pressure (BP) of their 10 healthy, recreationally active volunteers (23 yr, height 1.79m, weight 79kg) over a 24h period.
|Figure 1: Average plasma NO3 and NO2 levels in healthy male volunteers after the consumption of different amounts of beet root juice concentrate (Wiley. 2014)|
In that it's certainly remarkable that these effects lasted for 24h, so that the systolic blood pressure was still significantly lower (by 5 mmHg) than at baseline when the scientists took the last reading.
"[...S]ignificant main effects by dose and time and an interaction effect on systolic BP (all p < 0.05). [...] The peak reduction in systolic BP occurred 4 h postadministration of 4.2 (5 mmHg), 8.4 (10 mmHg), and 16.8 mmol NO3 (9 mmHg), respectively, relative to baseline (all p < 0.05). Systolic BP was reduced relative to baseline, CON, and 4.2 mmol NO3, at 2, 4, and 8 h postadministration of 8.4 mmol and 16.8 mmol NO 3 (all p < 0.05). There were no differences in systolic BP between 8.4 and 16.8 mmol NO 3 at any time point ( p < 0.05)." (Wiley. 2014)
Figure 2: The profound drop in systolic BP could be a problem if your BP is already low ➲ dizziness and -worst case- blackout!
Low blood pressure warning: For the average Westerner it certainly wouldn't be a problem if his blood pressure dropped by 10mmHg, but for a trained athlete who may already have a relatively low systolic BP, the high 16.8mmol (=280ml Beet It) could be straw that breaks the camels neck, i.e. make you feel as if you would black out (see Figure 2).A similar effect, albeit not dose-dependent effect was observed for the diastolic blood pressure, which dropped significantly, relative to baseline and CON (all p < 0.05). As the researchers point out, the peak reduction in diastolic BP from baseline occurred at 4 h postadministration of 8.4 mmol NO3 (3 3 mmHg) and 2 h postadministration of 16.8 mmol NO3 (4 4 mmHg; both p< 0.05) relative to baseline (both p < 0.05) and returned to near-baseline values by 24 h (p < 0.05).
"What about the really important stuff?"
Oh yes, I almost forgot the effects the scientists observed, when the subjects consumed the beetroot juice 2.5h before a "moderate- and severe-intensity exercise" in the form of a "step" exercise test (20W ➲ 93W ➲ 258W) on a cycle ergometer.
That's good for you, because as you can see on the right hand side of Figure 2, you do already have to consume more 1.3kg of unfertilized beet roots to get up to the medium and most effective dosage of 8.2mmol of nitrate.
- Hoon, Matthew W., et al. "The Effect of Nitrate Supplementation on Exercise Performance in Healthy Individuals: A Systematic Review and Meta-Analysis." International journal of sport nutrition and exercise metabolism (2013).
- Lee, C. Y., et al. "Nitrate and nitrite nitrogen in fresh, stored and processed table beets and spinach from different levels of field nitrogen fertilisation." Journal of the Science of Food and Agriculture 22.2 (1971): 90-92.
- Sindler, Amy L., et al. "Inorganic Nitrite Supplementation for Healthy Arterial Aging." Journal of applied physiology (Bethesda, Md.: 1985) (2014).
- Thompson, Kevin G., et al. "Influence of dietary nitrate supplementation on physiological and cognitive responses to incremental cycle exercise." Respiratory physiology & neurobiology (2013).