What is the DASH diet?
Diagnosed with high blood pressure and advised to cut back on your salt intake? Nutritionist Kerry Torrens takes a closer look at the DASH diet – what it is, how it may help and what its limitations are.
What’s the problem with salt in my diet?
Although over the last decade we’ve worked hard at reducing our salt intake, the average UK adult is still eating a third more than the recommended amount of 6g per day.
The problem with this is that consuming too much salt may lead to hypertension, more commonly referred to as high blood pressure, which is a major cause of stroke and heart disease. We all know friends who load salt on everything with seemingly no adverse effects, but researchers have discovered that for a number of us, salt may be a major factor leading to high blood pressure. That’s because some of us are genetically more susceptible to the effects of salt in our diets.
So why is this important? Well, high blood pressure makes the heart work harder, this creates extra force in the arteries which may damage them as well as organs such as the heart, kidneys, brain and eyes. Most people don’t even know they have high blood pressure but it affects about a third of all UK adults.
Discover our full range of health benefit guides and read more about popular diets such as the dopamine diet and Dukan diet. Also check some of these delicious DASH diet recipes, from a healthy porridge bowl to avocado & black bean eggs.
What is the DASH diet?
Recognising that diet plays a role in the development of high blood pressure, many doctors advocate a low-salt diet. The DASH (Dietary Approaches to Stop Hypertension) diet is one such eating plan. First introduced at a meeting of the American Heart Association in 1996 and later published in the New England Journal of Medicine in 1997. The diet offers a non-pharmaceutical strategy to help combat high blood pressure and reduce the risk of associated disease.
What are the principles of the DASH diet?
The DASH eating plan is based on heart healthy guidelines which limit the intake of fats, especially saturated and trans fats, and focuses on foods rich in nutrients known to lower blood pressure. These are typically foods low in sodium but rich in other minerals including potassium, magnesium and calcium. Overall the DASH diet limits sodium to between 1500mg and 2300mg (3.75g to 5.75g salt) a day.
The diet specifies a number of servings of each of the recommended food groups, the exact number being dependent on your calorie requirements, with plans based on 1600, 2000 or 2600 calories per day. A certain degree of meal planning is required but guidance and meal plan suggestions are available online.
What foods can I eat on the DASH diet?
On the DASH diet you’re encouraged to include fruit and vegetables, fat-free and low-fat dairy products, wholegrains, lean meats, poultry and fish, as well as unsalted nuts and seeds. Sweets and added sugars are limited. The amount you eat is based on the number of servings determined for your recommended calorie intake. A typical serving guide, based on 2000 calories a day, would look like this:
Food
Servings per day
Grains (preferably wholegrain)
6-8
Vegetables
4-5
Fruit
4-5
Fat-free or low fat dairy
2-3
Lean meat, poultry or fish
< 6
Fats and oils
2-3
Food
Servings per week
Nuts, seeds, dry beans
4-5
Sweets and sugars
<5
What foods should I avoid on the DASH diet?
The DASH plan recommends you minimise your intake of red meat, sweets, added sugars and sugary drinks, as well as foods with high levels of salt. It promotes more home cooking and reducing reliance on processed and packaged foods. Where packaged foods are used, the DASH diet recommends checking labels for nutrition facts so you can make informed decisions.
What are the benefits of following the DASH diet?
Following the DASH diet offers a number of health benefits, including:
- Lowers blood pressure – a consistent body of evidence supports the DASH diet’s blood pressure lowering potential, both for those with high blood pressure as well as for those with normal blood pressure.
- May relieve gout – when compared to a standard American diet (one high in red and processed meat, sugary drinks and refined grains), the DASH diet lowers levels of uric acid, suggesting that adoption of the diet may be beneficial for those with gout.
- Lowers the risk of type 2 diabetes – in similar fashion to diets like the Mediterranean diet, the DASH plan appears to reduce the risk of type 2 diabetes and possibly improves insulin resistance.
- Reduces your risk of kidney disease, despite other risk factors
- Weight loss is a welcome benefit for some DASH followers, this may be because of the reduction in the amount of high fat and sugary foods, as well as the calorie restriction determined by the plan.
- May reduce the risk of certain cancers, a positive association has been seen between adopting the DASH plan and the lower incidence of certain cancers. This may be because the diet is high in fibre and nutrient dense, although further studies are needed to ascertain the exact mechanism.
Like most eating plans the DASH diet is more effective when combined with lifestyle modifications including managing weight, getting regular exercise, stopping smoking and reducing alcohol consumption.
What are the limitations of the DASH diet?
The DASH diet encourages low-fat and fat-free dairy choices, however, based on more recent findings, this may not be necessary. Our knowledge of fats and their role in heart disease has advanced since the 1990s and its now recognised that full-fat dairy offers nutritional benefits such as supporting the intake of fat-soluble vitamins, including vitamins A and D. In recognition of this, a 2016 DASH study examined the effect of replacing low-fat dairy with full fat-alternatives and found the latter lowered blood pressure to the same extent as the original DASH diet, but interestingly also lowered blood fats as well as a type of cholesterol (vLDL), known to be associated with plaque formation in our arteries.
From a practical standpoint, and due to the need for a high degree of meal planning, compliance with the DASH diet appears to be low. Furthermore, if you’ve be used to eating a low-fibre, refined carb diet, you’d be best advised to introduce the recommended fibrous foods such as wholegrains, fruits and vegetables slowly, to allow your digestive system to adjust to the new foods.
Finally, those with food allergies (e.g. nuts) or intolerances (e.g. lactose) may need the help of a registered dietitian to help them adapt the plan to meet their specific circumstances.
What happens if I restrict my salt intake too much?
Sodium is an important electrolyte and plays a key role in the body, helping to maintain fluid levels and blood volume and facilitate nerve and muscle signalling.
Low levels of sodium may lead to a condition called hyponatremia, symptoms of which are similar to dehydration and include headaches, seizures, coma and even death. Older adults, especially those on medication, as well as athletes who take on a lot of hydration, are at greater risk of this condition.
For this reason, if you have a medical condition which requires a low-salt diet, or your GP or dietitian has advised you to limit your intake, you should continue to do so. However, if you are a healthy individual who has not been diagnosed with high blood pressure and cooks largely from scratch with minimal consumption of packaged or processed foods, then you may not need to adjust your current salt intake. If you are unsure you should refer to your GP for guidance.
If you are considering any significant changes to your diet, please consult your GP to ensure you can do so without risk to health. This is especially relevant if you are on medication, including those to manage blood pressure.
This article was published on 22 December 2020.
Kerry Torrens BSc. (Hons) PgCert MBANT is a BANT Registered Nutritionist® with a post graduate diploma in Personalised Nutrition & Nutritional Therapy. She is a member of the British Association for Nutrition and Lifestyle Medicine (BANT) and a member of the Guild of Food Writers. Over the last 15 years she has been a contributing author to a number of nutritional and cookery publications including BBC Good Food.
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