It’s not uncommon to arrive at your late forties and have the doc tell you you’re hypertensive. For many, the pressure of kids and a mortgage, accompanied by a lack of time for exercise, and the convenience of Maccas drive-through is enough to make blood pressure soar. When this lifestyle eventually culminates in hypertension, it’s time to have a long hard think about how to improve your health and bring that blood pressure back down. This is where the DASH diet comes in. It’s not easy and it’s not as fast as the name suggests, but hypertension is a huge risk factor for heart attack and stroke. So, if you want to live a long and happy life, read on!
DASH stands for Dietary Approach to Stop Hypertension. The only way to meet DASH requirements is to eat fruit, vegetables and whole grains in abundance and avoid processed sugary and fried foods. You will have to ditch the boxed pizza for meals that take a little bit more effort. Don’t worry, it’ll be worth it.
Let’s talk fat! When following the DASH diet, fat will make up 27% of your total energy intake (TEI). 27% is at the lower end intake recommended for the average person. By reducing overall fat intake, body weight can be controlled. Overweight and obesity induce chronic low-grade inflammation, which has contributions to hypertension, as well as cancer. What is most important about the DASH fat recommendation is that only 6% of TEI comes from saturated and trans fat. Take the example of a 50-year-old overweight woman who leads a sedentary lifestyle in an office job. Her daily energy requirements come in at around 8,700kJ/day. 27% of this is ~522kJ/day. There are around 37kJ/g in fat, so, the woman may consume no more than ~14g saturated and trans fat/day. Apply these calculations to yourself to determine your own recommended fat intakes. It is important the hypertensive population limits saturated and trans fat because such fats have marked increasing effects on bad cholesterol. This augments the build-up of plaque within the blood vessels, narrowing the lumen (opening for blood to pass through). Think about it like a straw; pushing a quantity of water through a thin straw requires a lot more pressure than through a thick straw. The same principle applies to your blood! By widening the lumen, through reductions in atherosclerotic plaque, blood pressure is reduced. To achieve the DASH recommendations for fat, fatty cuts of meat, fried and processed food will need to be strictly limited.
Salt is delicious! We love it on our chips, steak and eggs. Some people even like it in their chocolate milk! The salty goodness does, unfortunately, come with consequences. I’m sorry to say to, hypertensive folk, that you are going to have to kiss salty deliciousness goodbye. The DASH recommendation for salt is 2300mg/day which is considerably lower than the average Westerner’s dietary intake. Salt’s a tricky one because it’s hidden where you least expect it, particularly in restaurant foods and as a preservative in even sweet processed foods. Salt exists as NaCl on the table, but, it is the Na (sodium) we really have to worry about in the body. It is stored mainly in extracellular fluid, which includes blood. Here, it exerts an osmotic pressure that draws water to itself. Hence, increasing the water content and overall volume of blood. Back to the straw analogy; pushing a large volume of water through a straw takes a lot more pressure than if that volume was reduced, right? Well, the same thing with your blood. Increasing blood volume increases the pressure it exerts on the vessels, hence, causing hypertension. It is speculated, there is an internal homeostatic point set for sodium, and excess is excreted. If this were the case, you could eat it by the spoonful. Unfortunately, the excretion system is still somewhat misunderstood and unlikely to be able to deal with the copious Western diet. Furthermore, it is the current belief that only 20-25% of people are salt-sensitive-hypertensive, which means the excretion mechanism is vastly underdeveloped in these people. It’s good and bad news for this population. On one hand, blood pressure reduction will be especially effective by the reduction of salt. On the other hand, it is even more important they put down that salt ridden snack. In either case, salt reduction is still important.
Aside from increasing blood volume, salt promotes the excretion of calcium. Calcium is an excellent mineral for vasodilation. Vasodilation means relaxation muscles that surround the vessels, increasing the lumen. Hence, reducing the pressure of blood within the vessel. For this reason, high calcium is recommended by DASH (1250mg/day). This can be achieved by increasing dairy and leafy green vegetable consumption.
The DASH recommends high potassium at 4700mg/day. Potassium is found in dark green leafy vegetables, bananas and other fruit and vegetables. Unlike sodium, potassium promotes the retention of calcium, allowing blood vessels to reap it vasodilation effects. It also promotes the excretion of sodium, and you already know the benefits of this!
Similar to calcium, magnesium has blood pressure lowering effects. As such, it is recommended in high doses by DASH (500mg). Foods high in magnesium include nuts, whole grains and (yet again) green leafy vegetables.
Fibre has a plethora of health benefits, including some pertaining to cardiovascular health. For this reason, DASH recommends a high fibre intake of 30g/day. Fibre binds cholesterol and promotes its excretion. Due to consequential body cholesterol decline, cholesterol is removed from the blood to the liver for healthful purposes (for example, hormone and bile production). The lowered blood cholesterol resulting, reduces atherosclerotic plaque, increasing lumen and finally, decreasing blood pressure.
DASH is achievable only by consumption of plenty of fruit and vegetables and whole grains while avoiding sugary, processed, fatty foods. While this may be a shock to the system for the fast-food junkies out there, it is highly recommended for getting your health back on track!
Renae Earle is a Masters of Dietetics student at the University of Queensland. Having achieved her Bachelor of Exercise and Nutrition Science with distinction, she is motivated to complete her studies and become an accredited practicing dietitian.
Renae is passionate about evidence-based practice and debunking nutrition myths. She believes that in today’s fad celebrity diet culture, it is increasingly important to deliver the facts. She aims to help people achieve a sustainable and healthful lifestyle by combating the flurry of misinformation offered by tabloids and social media.
In order to achieve this goal, Renae has dedicated herself to the field of nutrition. She is well educated on a wide range of nutrition topics such as supplementation, chronic disease, restrictive diets and metabolism.
Renae has a keen interest in offering personalised nutrition plans that suit the specific needs of her future clients.