Beetroot and blood pressure Amrita Ahluwalia William Harvey Research Institute Barts & The London Medical School

High blood pressure- The silent killer! 1/3 of all deaths caused by CVD Pressures >140/85 No the sex I am interested in refers to differences between men and women with respect to their susceptibility to disease of the heart and the circulation. The heart and circulation are referred to collectively as the cardiovascular system, cardio representing the heart bit and vascular meaning the circulation (i.e. the blood vessels that carry blood around the body). Diseases of the CVS include heart attacks, stroke and high blood pressure. These diseases are a big problem in the UK with ~1/3 of all deaths due to CVD. Interestingly pretty much across all of the different diseases of the CVS there is an increased risk for men compared to women. So as an e.g. of this is a graph of the % of the UK population that have high blood pressure-hypertension, the men are in pink and the women blue-just challenging a few gender stereotypes there-and for those who know me well this wont be a surprise! But up until about the age of 65 its clear to see that more men get CVD than women. This is something that I have become progressively more and more interested in over the course of my career and my talk is peppered throughout with reference to this aspect of my work

Fruit and vegetables reduce blood pressure DASH study 459 participants 8 weeks Normotensive over 22 BP <160/95 Control diet potassium magnesium 25th percentile F and V 75th percentile for fruit veg intake and less snack/sweets Appel LJ et al,NEJM 1997;336:1117-1124

Vitamins increase all cause mortality! Vit A,E,C selenium and beta carotene 68 randomised trails with 232,606 participants both A and E increase mortality and C or selenium no effect. 46 studies with low bias Sasazuki looked at BP and vit c and found no effect in patients with helicobacter pylori Studies with benefit on smoking/cancer, respiratory tract infections, macular degeneration Bjelakovic, G. et al. JAMA 2007;297:842-857

Dietary nitrate Greatest protection of CVD afforded by green leafy vegetables (Joshipura et al, Anal Intern Med, 2001) Bioactivation of nitrate through enterosalivary circulation to nitrite and thence nitric oxide. Inorganic nitrite releases NO to cause vasodilation in humans

Dietary nitrate Greatest protection of CVD afforded by green leafy vegetables (Joshipura et al, Anal Intern Med, 2001) Bioactivation of nitrate through enterosalivary circulation to nitrite and thence nitric oxide. Inorganic nitrite releases NO to cause vasodilation in humans

cGMP Nitric Oxide NOS L-Arginine NO. NO2- NO3- O2 In 1994 2 groups simultaneously published that nitrate might provide a source of endogenous NO. Really both groups capitalised on studies in the early to mid 70s demonstrating that certain anaerobic bacteria found in the stomach or on the back of the tongue convert nitrate to nitrite and that this nitrite is then swallowed Both ben Jon wondered whether this might be a route for NO generation. Separately using slightly different techniques NO3-

Nitric Oxide NOS L-Arginine NO. NO2- NO3- Chemical acidification Bacterial anaerobes Chemical acidification NO2- In 1994 2 groups simultaneously published that nitrate might provide a source of endogenous NO. Really both groups capitalised on studies in the early to mid 70s demonstrating that certain anaerobic bacteria found in the stomach or on the back of the tongue convert nitrate to nitrite and that this nitrite is then swallowed Both ben Jon wondered whether this might be a route for NO generation. Separately using slightly different techniques NO3- Benjamin et al , Nature. 1994;368:502 Lundberg , Weitzberg et al , Gut. 1994;35:1543-1546.

Entero-salivary circulation • NO3- • NO2- • NO

Dietary nitrate Greatest protection of CVD afforded by green leafy vegetables (Joshipura et al, Anal Intern Med, 2001) Bioactivation of nitrate through enterosalivary circulation to nitrite and thence nitric oxide. Inorganic nitrite releases NO to cause vasodilatation in humans

The beetroot! Healthy volunteers (normotensive) Beetroot juice (500ml) Assessed: Plasma Nitrate/nitrite Blood pressure

Plasma Nitrate/Nitrite

Ingestion of dietary nitrate elevates circulating nitrate and nitrite Healthy Volunteers N=14 Juice [nitrate]=45±2.6 mM Webb et al. 2008, Hypertension, 51, 1-7.

The enterosalivary circulation Normal Healthy Volunteers N=6 Juice [nitrate]=34 +/- 0.1 mM Webb et al. 2008, Hypertension, 51, 1-7.

Blood Pressure

Elevation of circulating nitrite correlates with a decrease in blood pressure

The enterosalivary circulation and blood pressure

Does nitrate supplement act like beetroot? What is the dose-response for beetroot?

Does nitrate supplement act like beetroot? What is the dose-response for beetroot?

Nitrate supplement mimics beetroot juice Plasma Nitrate/Nitrite Normal Healthy Volunteers N=18 KNO3=24 mmol KCl control

Nitrate supplement mimics beetroot juice Blood pressure Normal Healthy Volunteers N=20 KNO3=24 mmol Kapil et al 2010 Hypertension in press

Does inorganic nitrate act like beetroot? What is the dose-response for beetroot?

Dose-dependent effects

• NO3- • NO2- • NO

Nitric oxide and hypertension NOS L-Arginine NO. Bacterial anaerobes Blood vessel nitrite reductase NO2- In 1994 2 groups simultaneously published that nitrate might provide a source of endogenous NO. Really both groups capitalised on studies in the early to mid 70s demonstrating that certain anaerobic bacteria found in the stomach or on the back of the tongue convert nitrate to nitrite and that this nitrite is then swallowed Both ben Jon wondered whether this might be a route for NO generation. Separately using slightly different techniques NO3-