Broccoli and Vascular Health Study

This intervention will take place at two independent sites, The Institute of Food Research's Human Nutrition Unit (HNU)in Norwich and the Hugh Sinclair Human Nutrition Unit (HSU), at the University of Reading. The participants recruited from Norwich and Reading will solely attend the unit in their area and the paper work has been written to reflect this i.e.separate participant information sheets (PIS). In addition to the tests carried out at both sites, the Reading cohort will also undergo additional vascular tests, also reflected in the PIS. Despite the sites being independent, 96 participants will be recruited across both sites, with the possibility of uneven numbers from each site making up the final number.

The purpose of this study is to assess whether diet can affect an individuals chances of developing CVD, as it is one of the biggest killers in the UK. We are particularly interested in participants who have a 10%-30% risk of developing CVD. We are able to assess a person's risk with the help of the Joint British Societies 2 guidelines on the prevention of cardiovascular disease, cardiovascular disease risk prediction chart. These charts take a number of parameters we obtain from the participant, their age, sex, total cholesterol concentration, systolic blood pressure (BP), body mass index (BMI), serum high density lipoprotein concentration, their smoking status and diabetes status and put them into an algorithm. The result is a risk score out of 100, of a person developing CVD over the next 10 years.

The study will be conducted over two sites, Reading and Norwich, with a principal investigator assigned to each site. The total number of participants recruited over both sites will be 96. It may be that uneven numbers are recruited over the two sites e.g. 46 at one and 50 at another however regardless of the number at each site, 48 participants will be assigned to each of the two groups. One group will consume 400g of the commercially available high glucosinolate Beneforté® broccoli each week for 12 weeks and the other will consume 400g of a standard broccoli, Parthenon for 12 weeks.

As we are assessing the effect of diet on CVD risk, our participants will be screened initially. Their urine will be tested (urine dipstick test), their height, weight, waist and hip measurements, BMI, BP will be measured and questions linked to lifestyle choices (alcohol consumption, smoking status and physical activity) will be asked. A separate section pertaining to women's health will also be present on the questionnaire.

All participants will be asked to give written informed consent before they can participate in the intervention study. The Reading cohort will be sent a copy of the consent and medical declaration forms to read through at home. The forms sent to the homes will be clearly distinguishable from the real forms as they will have the watermark with "SAMPLE" written across them.

CVD risk assessment calculator This calculator will be used once the results of the screening are known. A program devised by the University of Manchester will be used to calculate the risk our participants have of developing CVD over the next 10 years. This program is based on the Joint British Societies 2 guidelines on the prevention of CVD risk prediction charts. For the purposes of this study we would like our participants to fall into the 10%-30% risk category as most literature suggests people in this range may benefit from dietary change, without the need for medication, in the most part. The CVD risk scores will be sent to the participants GP and we will continue to advise our participants to discuss the results with their GPs if they score >10%.

Genotyping There is evidence to suggest that a person's genetic make-up may affect the way isothiocyanates (ITCs), one of the active components of broccoli, work. Of the 30,000 genes found in humans a group of genes associated with the protein glutathione S-transferase M1 (GSTM1) has been shown to affect ITCs after consumption and has been implicated in CVD. There is evidence to suggest that individuals with a deletion in GSTM1 breakdown the glucosinolate, from which the ITC sulforaphane is derived, differently to individuals that have the gene. We also know that glutathione S-transferase theta-1 (GSTT1) may also be involved in reducing the likelihood of developing CVD.

Along with the GST gene family and their association with cruciferous vegetables, there are a number of other genes that have been implicated in CVD itself. These include genes associated with lipid metabolism, thrombosis, leukocyte adhesion and nitric oxide production and thus blood vessel dilation. This is by no means an exhaustive list and will therefore remain open to other viable candidates.

Vascular measurements As we age, our arteries stiffen which causes an increase in the demands of the heart and an increase in blood pressure. This increase in BP can dramatically increase the risk of heart attack, stroke and heart failure. Arterial stiffness has also been associated with many of the common risk factors associated with CVD such as age, high blood pressure, smoking, cholesterol levels and obesity, but importantly, arterial stiffness has been shown to be an independent predictor of CVD in a large section of society.

There are many ways in which arterial stiffness can be assessed. We will be looking at blood pressure, which will be very familiar to most participants in our age range (over 50yrs of age). The only difference being that the participant will wear a cuff for an hour and readings will be collected every ten minutes.

Another method will be Pulse Wave Analysis (PWA), where a probe will be held against the neck and the upper thigh to take the measurements for up to a minute at a time. As participants may not be wholly familiar with this technique, it is hoped that a short video clip could be shown on a laptop or diagrams/photographs of the technique will be discussed with the participant at screening.

Restricted conditions prior to study day Before the study day the participants will be asked to abstain from a number of activities. This will be clearly stated in the PIS.

These include:

1. No alcohol or caffeine for 24 hours before the study day. Participants who consume a lot of caffeine will be advised that they may suffer from headaches. They will be asked to tell the study scientist if they needed to take any medication as a consequence.
2. Low fat meal to be consumed the night before the study day. Participants will be asked to eat a low fat meal from a selected list that we give them. We will ask that the meal is consumed before 10pm, as the participants will then have to fast for their study day.
3. Fasting for at least 8 hours. Participants will need to fast for at least 8 hours. This means that they won't be able to eat or drink anything, apart from water during this time. They can drink as much water as they feel they need.
4. No heavy exercise the morning of their study day. Participants will be asked not to engage in any vigorous exercise the morning of their study day. This will be defined as any activity that causes an increase in heart rate, panting and/or sweating. A participant who normally cycles will be asked not to on the morning of their study day.
5. No smoking an hour before their study day measurements. All participants that smoke will be asked to abstain from smoking at least an hour before their study day. We would also ask that they avoid all passive smoking.