The right diet for high blood pressure
Exercise and good food, rather than supplements, are key to lowering high blood pressure
Too much table salt can raise our blood pressure and adjusting to a lower salt diet can take up to eight weeks, so you need to persevere. Photograph: Thinkstock
Typically, blood pressure rises and falls throughout the day. When it stays raised and uncontrolled over time, it makes the heart work harder and forces the blood through the arteries. This increased pressure causes damage to the arteries and can lead to heart and kidney disease, as well as stroke.
The evidence suggests that the Dash plan (dietary approaches to hypertension) is the best pattern of eating to prevent or treat high blood pressure.
Steps to control high blood pressure
-Take blood pressure medicine as prescribed
-Drink alcohol in moderation
-Follow a low-salt Dash plan
-Maintain a healthy weight
-Exercise and be active
Principles of the Dash plan
Low in salt and saturated fat, but high in magnesium, potassium, calcium and fibre High in fruit and vegetables Includes only wholegrain products and low-fat dairy Includes lean meats, fish, poultry and nuts Low in red/processed meat, sweets and sugared beverages
“There is no harm in adopting this eating pattern, even if you are taking blood pressure medication,” says Aoife McCarthy, a cardiology dietitian at Cork University Hospital. However, it is important to consult with the family doctor first, in case there are any contraindications. For example, the Dash plan may not be suitable for patients with pre-existing kidney impairment.
It is important to continue taking your blood pressure medication while making dietary changes. As the diet lowers blood pressure, some people can experience side effects such as dizziness. This may mean that your blood pressure medication needs to be adjusted to reflect the improvements in diet and weight loss you have made, according to McCarthy.
Salt and substitutes
Many of us are aware that too much table salt can raise our blood pressure. As a specialist dietitian, McCarthy
is frequently asked about substitutes such as healthier- sounding salts. Pink Himalayan salt is currently a popular alternative to table salt. “For people who have no known co-morbidities or who are not on medication, Lo-Salt (potassium chloride) is suitable to use. But other types of salt, for example sea salt, pink Himalayan salt and kosher salt, are all similar to table salt and are not suitable substitutes. Adjusting to a lower salt diet can take up to eight weeks, so you need to persevere,” says McCarthy.
Changes to labelling regulations are helping to clear up some confusion around the salt content of foods. Sodium levels were often given in the past without the salt equivalent. It is now mandatory for salt, not sodium levels, to be declared per 100g of a food. This will make similar foods and meals easier for people with high blood pressure to compare.
Behavioural change is difficult, and McCarthy highlights the relationship between being overweight and having high blood pressure as an issue that many people avoid tackling. She also points to the fact that many people are still unaware of the link between too much alcohol and high blood pressure.
The promise of heart health comes in an increasing variety of nutrition supplements too. Investing in individual nutrients and dietary components rather than food is not recommended, as foods provide a variety of phytochemicals, vitamins, minerals, bioactive compounds and fibres that are not commonly found in supplements.
The American Heart Association recently reviewed its recommendations about common supplements to drive home the message that there is “no substitute for a balanced diet that limits excess calories, saturated fat, trans fat, sodium and dietary cholesterol”. Its recommendations about supplements are as follows:
What to do
Patients with heart disease should consume about 1g of omega-3 fatty acids called EPA/ DHA. This should ideally come from fish. This can be hard to get by diet alone, so a supplement could be needed. As always, consult with a physician first.
If you have elevated triglycerides, try to get between 2g and 4g per day of EPA/DHA.
What not to do
Don‘t take antioxidant vitamin supplements such as A, C and E. Scientific evidence does not suggest these can eliminate the need to reduce blood pressure, lower blood cholesterol or stop smoking.
Do not rely only on supplements. There isn’t sufficient data to suggest that healthy people benefit by taking certain vitamin or mineral supplements in excess of the daily recommended allowance. Some observational studies have suggested that using these can lower rates of cardiovascular disease and/or lower risk factor levels. However, it’s unclear in these studies whether supplements caused these improvements. See iti.ms/1PaMuVs
Instead of eating more fruits, vegetables and moderate amounts of low-fat dairy, as the Dash plan suggests, some patients may be intent on increasing dietary minerals (potassium, calcium and magnesium) through supplementation. McCarthy stresses the phrase “food first”. Her recommendations about common supplements for blood-pressure management are as follows:
Specifically in relation to blood pressure, there is no evidence to support the use of antioxidant supplements. The research on the Dash
diet plan is based on consuming the foods and not the individual nutrients, and we cannot expect the same effect from taking a supplement to substitute for the recommended dietary changes in the Dash plan.
Owing to Ireland’s northerly latitude and long winters, Irish people are at a higher risk of vitamin D deficiency. Supplementation of vitamin D is recommended by the Food Safety Authority of Ireland (FSAI) for overall health and wellbeing. In relation to blood pressure, however, there is no evidence to support additional supplementation.
Omega-3 fatty acids have a modest effect on lowering blood pressure; however, the effects are not sufficient to recommend fish oil supplements for the management of hypertension.
Other ‘heart healthy’ supplements ‘scientifically proven to work’
There are many products on the shelves of supermarkets and health food shops all claiming to improve heart health in a variety of ways. Blood pressure is one of a group of risk factors contributing to the risk of cardiovascular disease.
The advice from the cardiac dietitian is to “include a variety of foods in your diet similar to the Dash plan, rather than investing in an array of expensive supplements”. Compliance with supplements is poor in the long term and often the nutrient is already contained in commonly eaten, inexpensive foods; for example, beta glucan is found in oats.
Supplements don‘t substitute for other important lifestyle changes such as losing excess weight, building more exercise into the week, taking blood pressure medication as prescribed, and reducing the salt content of our diet.
Paula Mee works at Medfit Proactive Healthcare and is a member of the Irish Nutrition and Dietetic Institute.
See medfit.ie; @paula_mee