Diet and food

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Answers to the most common questions about the effects of food and diet on blood pressure.

Diet and food

Is potassium helpful? Should I take a supplement?

It is true that eating potassium helps to lower blood pressure in part by counteracting the effects of sodium in “salt” and influencing the amount of fluid in our bodies. For people eating a healthy diet, it is very rarely necessary to take potassium supplements and they are not recommended unless they have been prescribed by a doctor. This is because too much potassium can be harmful, especially if you have kidney problems or you are taking medicines that might already have elevated the amount of potassium in your body.

Because of this, you also need to be careful if you are using a salt substitute, as these may contain particularly high levels of potassium and you should discuss this with your doctor before using them. The best way to ensure you have a healthy intake of potassium is to eat a healthy, balanced diet.

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Why is obesity linked to blood pressure?

It is not completely understood how obesity is linked to high blood pressure, but it is certainly true that being overweight increases your blood pressure.

Your blood pressure is controlled by a number of different pathways – from how hard and fast your heart beats, through the release of different hormones, to how much fluid your kidneys remove from your body. Carrying too much fat appears to affect one of the hormone pathways – the renin-angiotensin system – causing blood pressure to rise. It also interferes with the kidneys’ abilities to remove fluid, and this too causes blood pressure to rise. In addition, overweight people are more likely to consume more salt.

The good news is that is losing weight will help. In fact, if you are overweight, it has been found that losing 10kg can lower your blood pressure by 5-10mmHg.

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Does eating oily fish help with high blood pressure?

Oily fish, for example sardines, trout, salmon and mackerel, is rich in ‘omega 3’ fatty acids. One study has shown that fish oil supplements, when taken in large amounts (3g daily) do show a small reduction in blood pressure. However, such a large amount could be difficult to take every day.

However, eating oily fish can help to regulate your cholesterol levels. This means that your overall risk of a heart attack or stroke may come down. Try to eat fish at least twice a week, including one portion of oily fish. Recently, there have been some concerns about residues in oily fish, particularly mercury. It is probably sensible, therefore, not to eat large amounts of oily fish, i.e. only one portion a week.

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I use a bread maker, but it says I need to use salt - do I?

Salt is totally unnecessary for making bread. Its main use in bread is to slow down the fermentation of the yeast so, without it, the bread rises quicker. Once you are used to the taste, it is fantastic – the only problem is you will want to eat too much of it!

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What are trans fatty acids and how bad are they?

Fats are made up of two main types of fatty acids: saturated and unsaturated fatty acids. Unsaturated fatty acids are found in liquid vegetable oils, while saturated fats are found in solid animal fats.

To turn liquid vegetable oils into solid fat for margarines, biscuits, cakes, and other processed foods, hydrogen is added (known as hydrogenation).  During this process, trans fatty acids may be formed. Trans fatty acids raise the level of “bad” LDL cholesterol in your blood, increasing the risk of heart disease. Some evidence suggests that trans fats may be even worse than saturated fats at raising LDL cholesterol levels.

So, as well as avoiding foods that contain saturated fats, you should also try to cut out “hydrogenated” fats.

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