Vegetables are not just healthy and support your immune system a recent study from the University of Exeter also suggest vegetables rich in nitrates (such as beetroots, spinach, lettuce or radishes) may help to improve your stamina.

The research team around Professor Andy Jones tested the effects of organic nitrate supplementation or simply a diet with foods high in nitrates (beetroot juice) in 8 males. Their assumption was that the consumption of beetroot juice would reduce blood pressure in the test condition and moreover that with a diet high in beetroot juice the muscle oxygen needs in low intensity exercise (i.e. jogging) would be reduced and in high intensity exercise (sprint to exhaustion). This would lead to greater tolerance or better performance.

Their subjects consumed about 500ml of beetroot juice per day and this was found to decrease blood pressure, the needs of the muscles for oxygen in low intensity exercise and in high intensity exercise it led to improved performance (or longer sprint time).

These findings are however not just important to athletes and people who are physical active. These insights may also help older people who suffer of breathlessness or people who are unable to be physical active, because it appears that nitrate enhances muscle respiration which in turn improves the oxygen supply to body cells, which is vital for cell function.

The believed process by which nitrate improves muscle or cell respiration is the transformation of nitrate into nitrate oxide which may supply extra oxygen on cellular level. If this should be true than other vegetables high in nitrate such as spinach, radishes or lettuce may provide similar improvements to stamina or performance.

Nitrate seems also to improve blood pressure which in turn might be one of the explanations for the commonly found lower blood pressure and lower cardio vascular risk in groups which consume high fruit and vegetable diets. A study of the Barts & the London School of Medicine and Dentistry and the Peninsula Medical School supplied further support for this as healthy volunteers had lower blood pressures 3 hours after consuming 500ml of beetroot juice.

Their observations also suggest nitrate affects blood vessels and platelets therefore it is assumed nitrate may also be preventive for cardio vascular disease. Therefore diets rich of vegetables with high nitrate content could help people which suffer of high blood pressure and are potentially helpful if one would aim to increase stamina.

References:

Aboud, Z., Ahluwalia, A., Benjamin, N., Deanfield, J., Hobbs, A.J.,  Loukogeorgakis, S., MacAllist, R., Miall, P., Misra, S., Okorie, M., Patel, N., Rash, R., and A.J. Webb (2008) Acute Blood Pressure Lowering, Vasoprotective, and Antiplatelet Properties of Dietary Nitrate via Bioconversion to Nitrite, Hypertension, 51: 784-790

Bailey,S.J., Blackwell, J.R., Benjamin, N.,  DiMenna, F.J., Andrew M. Jones, A.M., Tarr, J., Vanhatalo, A., Wilkerson, D.P. and P. Winyard (2009) Dietary nitrate supplementation reduces the O2 cost of low-intensity exercise and enhances tolerance to high-intensity exercise in humans, Journal of Applied Physiology, doi:10.1152/japplphysiol.00722.2009

Article by Andrea Zick  Esteem Fitness Nutritionist London
Esteem Fitness Personal Trainers London and the South East UK