The effect of concentrated beetroot juice with or without vitamin C on the levels of N-nitroso compounds in urine

The interest in consumption of nitrate-rich red beetroot juice has increased
greatly over the last couple of years. Beetroot juice contributes to the
formation of endogenous nitric oxide, causing a number of beneficial effects.
However, since beetroot juice is very rich in nitrate, consuming this product
may also cause endogenous formation of N-nitroso compounds, which are
considered to be carcinogenic. Furthermore, we will examine what the effect is
of supplementation with vitamin C on the endogenous formation of N-nitroso
compounds. Studies show that vitamin C can decrease the formation of these
compounds, which could potentially mean that consuming beetroot juice in
combination with vitamin C would diminish potential negative side effects of
this consumption.

The main aim of the study will be to compare the urinary N-nitroso compounds
levels after intake of 70 ml of concentrated red beetroot juice containing 400
mg nitrate either with or without supplementation with 1 g vitamin C.

The participants will be randomized equally to the groups. Half of the study
population will orally consume red beetroot juice without vitamin C for a
single week. The other half of the study population will orally consume red
beetroot juice in combination with vitamin C for a single week.

Beetroot-juice will be consumed by both groups. However, the intervention group
will also consume vitamin C in addition.

The consumption of beetroot-juice can cause gastro-intestinal distress on the
short-term. Thereby, it can cause beeturia (red colouring of urine) and a
headache. Exposure to beetroot-juice during a longer period of time, can
increase the risk on cancer due to the formation of N-nitroso compounds.
However, in this study participants will only consume beetroot-juice during a
relatively short period of time.