What is the DASH diet?

Too much salt in your diet may lead to hypertension, more commonly referred to as high blood pressure, which is a major cause of stroke and heart disease. When your blood pressure is elevated, it makes the heart work harder, this creates extra force in the arteries which may damage them as well as other organs such as the heart, kidneys, brain and eyes.

Most people don’t even know they have high blood pressure but it affects about one third of all UK adults. Researchers discovered that for a certain number of us, salt may be a major factor leading to high blood pressure. This is because some of us are genetically more susceptible to its effects.

What is the DASH diet?

Recognising that diet may play 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 example. First introduced by the American Heart Association in 1996 and later published in the New England Journal of Medicine, the diet offers a non-pharmaceutical approach to combat high blood pressure and reduce its associated risks.

How does the DASH diet work?

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 the nutrients known to lower blood pressure. These are typically foods low in sodium (salt) but rich in other minerals including potassium, magnesium and calcium. Overall, the DASH diet limits sodium to between 1500mg and 2300mg – that’s 3.75g to 5.75g – per day.

How do I follow the DASH diet

The diet specifies the number of servings for each of the recommended food groups per day, the exact number is dependent on your calorie requirements with plans based on 1600, 2000 or 2600kcal. A certain degree of meal planning is required but guidance and recipes 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. The amount you eat is based on the number of servings determined for your specific 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 foods. Where packaged foods are used, the DASH diet recommends checking nutrition labels so you can make informed decisions.

What’s the evidence for the DASH diet?

Studies suggest following the DASH diet may offer a number of health benefits, these include:

1. 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.

2. 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.

3. Lowers the risk of complications associated with type 2 diabetes

In similar fashion to diets like the Mediterranean diet, the DASH plan appears to reduce the risk of complications from type 2 diabetes and possibly improves insulin resistance.

4. Reduces risk of kidney disease

Studies suggest this may be due to the lean protein, low-fat dairy, nuts and legumes which are consumed as part of the diet.

5. Weight loss

This is a welcome benefit for some DASH followers – it 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.

6. 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 is 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.

Is the DASH diet healthy? Our nutritionist’s view…

The DASH diet offers a balanced eating plan for managing blood pressure. Although the original DASH diet encourages eating low-fat and fat-free dairy foods, more recent findings suggest 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 our 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. Interestingly, it also also lowered blood fats as well as a type of cholesterol (vLDL), known to be associated with plaque formation in our arteries.

Compliance with the DASH diet appears to be low due to the high level of meal planning which is required. Furthermore, if you’ve been used to eating a low-fibre, largely refined carb diet, it’s best to introduce the recommended fibrous foods such as wholegrains, fruits and vegetables gradually, 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 their specific circumstances.

Who should not follow the DASH diet?

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 are at greater risk of this condition.

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.

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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 reviewed on 9 November 2023 by Kerry Torrens

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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