The effect of delivering dietary nitrate via different food matrices on blood pressure in normotensive volunteers

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Caroline Day completed the Summer Studentship at the Nutrition and Dietetics Department at King’s College London under the supervision of Dr Trevor George.  Caroline, myself and Harriet Smith also run Fight the Fads, a nutrition media platform that addresses and corrects misinformation in the media with evidence-based science. You can find FTF on Twitter and Instagram.
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Project Title: The effect of delivering dietary nitrate via different food matrices on blood pressure in normotensive volunteers

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About the project:

My project investigated the effect of the consumption of dietary nitrate, consumed in the form of both beetroot bread and beetroot juice, on blood pressure.

Increased vegetable consumption has been associated with a reduction in blood pressure and reduced risk of cardiovascular disease. Originally, this association was thought to be a result of the anti-oxidant properties of vegetables. More recently however the effect vegetable nitrate on blood pressure has been investigated. Vegetables including beetroot have a high nitrate content which after ingestion is reduced endogenously to nitric oxide, a potent vasodilator. Previous studies have found the consumption of beetroot juice is associated with a significant reduction in systolic blood pressure.  This could have important clinical relevance if the dietary nitrate in beetroot could be transferred to a commonly consumed food such as bread, which could then be used in the lifestyle management of hypertensive patients.red-beets-1725799_1920.jpg

Whist some studies have found that beetroot enriched bread products also reduced blood pressure in normotensive subjects, no studies had compared the effect of delivering nitrate via bread and juice using beetroot from the same source, so direct comparisons of the efficacy of each method of delivery have not been possible. My project aimed to create a novel beetroot bread product to establish if it was possible to create the same blood pressure lowering effect as when the same source of beetroot was consumed as a juice.

beet-1637437_1920.jpgAdditionally, I wanted to test if my increasing the nitrate content in the novel beetroot bread, it was possible to create further reductions in blood pressure.

My results demonstrated that the  both beetroot juice and beetroot bread lowered blood pressure in participants. After the consumption of beetroot bread, blood pressure remained lower for two hours longer than beetroot juice consumption.

What was the best aspect of your Summer studentship experience?

Having the opportunity and funding to design and implement your own research idea is an invaluable experience. I am considering expanding the study for my dissertation project next year, I have gained skills so many areas that I can take forward with me to make this process much smoother! Particularly in participant recruitment, project planning and data analysis.

What was the most challenging part of your studentship?

Learning to adapt when the project didn’t go to plan. Adding beetroot extract to a standard bread recipe presented many challenges. I had originally intended to maximise the nitrate content of the bread by using a concentrated beetroot juice extract. Unfortunately, the high sugar content of this extract killed the yeast in the standard bread recipe and my loaf ended up more like a cake. This then delayed the project as I had to source and trial other forms of beetroot extract. After two disappointing weeks of trial and error, and thirty loaves of unusable bread I finally found a recipe that worked. This has taught me that patience and flexibility are crucial skills for working in research!

What’s the one thing you learnt that is transferable to future work you might do?

My study was powered for 24 volunteers and only 9 were recruited, so the results do not have sufficient statistical power to draw conclusions even though a pattern was observed. Experiencing the difficulties of participant recruitment has been very useful as this is something I will need to do on a larger scale for my dissertation.

Tips for anyone who is interested in applying for the NS – SS or a similar fellowship:

When researching your project for the application process, I would recommend exploring a number of different project ideas. Speaking to researchers in different areas and thoroughly explore the literature. By doing this I gained a lot of knowledge in different research areas before deciding on my final topic, which helped both with the planning of chosen project and has sparked ideas for future research.

Would you be interested to do more research in the future and if so what topic(s) would interest you?

I am hoping to continue this project as part of my final year dissertation with a larger sample size. There is also the potential to test the bread products on participants with hypertension as all the studies to date have used normotensive subjects.

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The Nutrition Society (NS) offers a unique funding opportunity to a limited number of students to undertake a research project during the summer months. The Summer Studentship Series is a collaboration with six students that took part in the 2016 NS Summer Studentship (NS-SS). I decided to ask everyone a couple of questions related to their projects and general experience, in an attempt to give you an idea of the variety of projects we completed and the interesting elements of each project. My hope is to inspire more students to do research and provide useful information and tips for those who may be interested in applying for the NS Summer Studentship or other similar research projects. I firmly believe research is the way forward in nutrition and I hope these series inspires more of you to get involved in research projects. This year’s Nutrition Society Summer Studentship application is now open and you can find it here.

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