Diet for hypertension: what to eat to lower blood pressure

From what readings is blood pressure considered high?

We speak of hypertension when blood pressure measured in the clinic is 140/90 mmHg or higher, according to the European hypertension guideline [1]. Between 120 and 139 systolic, or between 70 and 89 diastolic, is called elevated blood pressure [1].

These are the two numbers in which blood pressure is written. The top one is the force with which the heart pushes blood when it beats, and the bottom one is what remains between beats.

This classification helps you understand what you are being told. The number you need to reach is decided by the person treating you, because it depends on your age, your cardiovascular risk and what you take. We work on food so that the number comes down.

A single reading does not diagnose anything. High blood pressure is confirmed with readings taken outside the clinic, including at home [1].

How much salt should you cut, and where does the salt you eat come from?

The European guideline recommends less than 5 g of salt a day, equivalent to about 2 g of sodium [1]. Hypertension guidelines also recommend reducing sodium [1] [2].

Much of that sodium comes through processed foods [1]. The salt cellar on the table is the small, visible part. The large part was already inside the bag, the jar or the tray. It is in bread, cold cuts, cured cheese, tinned food, sauces, stock cubes and ready meals.

With high blood pressure, the work is more in the shopping than in the kitchen.

The label is the tool. By law, a food can only claim “low sodium or salt” if it does not exceed 0.12 g of sodium per 100 g or 100 ml [3]. Use it as a reference when comparing two jars at the supermarket.

Three habits that are worth more than removing the salt cellar:

• Buy bread without salt or low in salt.
• Rinse pulses and jarred vegetables under the tap for a minute.
• Replace stock cubes with homemade stock of leek, carrot and bay leaf, which freezes in ice-cube trays.

How to increase potassium, and when not to

The potassium in food is also taken into account when organising the diet for high blood pressure [1]. The plan must be adapted if there is kidney disease or medicines that alter its levels.

This is achieved by eating, not with capsules: vegetables, fruit, pulses, potato, unsalted nuts and low-fat dairy.

In people with high blood pressure who eat a lot of salt and do not have moderate or advanced kidney disease, increasing potassium by between 0.5 and 1 g a day may be considered [1]. This is done with more fruit and vegetables or with a low-sodium salt enriched with potassium [1].

Do not switch to potassium salt on your own. If you have kidney disease or take medicines that can raise potassium, the team must assess kidney function and monitor blood potassium before recommending it [1]. The European guideline allows an individual possibility, not an absolute ban for all these situations.

Medicines that can raise potassium include some diuretics, such as spironolactone, and ACE inhibitors or ARBs, such as enalapril or losartan [1]. Discuss your treatment before using a potassium-enriched salt.

If you have kidney disease, your nephrologist or dietitian will tell you how much protein, potassium, phosphorus and other ions and minerals suit you at your stage. You can read the diet for chronic kidney disease. In any of these cases, do not buy potassium salts on your own.

What is the DASH diet and how is it similar to the Mediterranean diet?

DASH stands for “Dietary Approaches to Stop Hypertension”, an eating plan designed by the US National Heart, Lung, and Blood Institute [4]. It is based on daily and weekly targets for food groups, with no special foods or branded products [4].

These DASH servings correspond to an illustrative pattern of 2,000 kcal a day [4]. They are not the automatic amount for a sedentary older person: energy needs and servings change according to activity and clinical situation. In brackets, what counts as one serving is indicated [5]:

• Grains, 6 to 8 (one slice of bread or half a cup of cooked rice or pasta).
• Vegetables, 4 to 5 (one cup of raw leafy greens or half a cup of chopped or cooked vegetables).
• Fruit, 4 to 5 (one medium piece or half a cup of chopped fruit).
• Low-fat, sugar-free dairy, 2 to 3 servings (one cup of milk or yoghurt, or about 40 g of cheese).
• Meat, poultry or fish, 6 or fewer (about 30 g cooked, or one egg).
• Fats and oils, 2 to 3 (one teaspoon of oil).

Nuts, seeds and pulses come to 4 to 5 servings a week [4]. Each serving is about 40 g of nuts, two tablespoons of seeds or half a cup of cooked pulses [5].

The original plan gives its own sodium figures [4]. For this guide, follow the general reference: less than 5 g of salt a day, about 2 g of sodium [1].

Read from our perspective, that list is almost the traditional Mediterranean shopping list. Today a healthy pattern, such as the Mediterranean or DASH, is recommended to lower blood pressure and cardiovascular risk [1].

What differs is where the fat comes from, which here is provided by extra virgin olive oil. The full Mediterranean pattern is in the anti-inflammatory diet.

How much does blood pressure fall with weight loss, exercise and less alcohol?

Quite a lot, and here there are numbers. According to the European guideline, losing an average of 5 kg is associated with an average fall of 4.4 mmHg in the systolic reading and 3.6 in the diastolic [1].

If you are overweight, that is the biggest lever you have. The reference is a body mass index, weight divided by height squared, between 20 and 25 [2]. How to work on it without going hungry is in the weight-loss diet.

Regular aerobic exercise helps lower blood pressure [1]. Start with an activity you can sustain, and check how to adapt it if you have frailty, falls or symptoms when you stand up; an individual fall in reading cannot be promised.

Hypertension guidelines recommend reducing alcohol or avoiding it [1] [2]. If you take medication, are pregnant or need to drive, follow the relevant advice; do not treat any consumption figure as a guarantee of safety.

And coffee, tea and other drinks?

Here we change what we used to say, and it is worth saying so clearly. Coffee is not discouraged. The European guideline says that drinking coffee is not associated with a higher risk of hypertension in the general population, and that it might even be associated with a lower risk [1].

On tea and cardiovascular disease, the data are not conclusive [1]. If your blood pressure is not controlled, talk to your doctor about coffee.

What does raise blood pressure, acutely, are energy drinks with a lot of caffeine and taurine [1]. Soft drinks and packaged fruit juices should be limited for another reason: free sugar, which should be kept below 10 % of daily calories [1].

With bottled water, checking the sodium on the label and choosing a low-mineral water is a sensible step.

Does blood pressure management change in older people?

Age alone does not require a different diet or stopping medication. The European guideline distinguishes situations: at 85 or older, or with previous symptomatic orthostatic hypotension, a less strict blood pressure target may be accepted [1].

In moderate or severe frailty, or with a life expectancy of less than three years, it recommends particular caution and individualisation [1]. Dizziness on its own does not confirm orthostatic hypotension. Do not change medicines on your own.

The recommendation to reduce salt for the general population does not automatically apply in the same way if you take diuretics, feel dizzy on standing, have had falls or have other problems; review the plan with your doctor.

Nor does it mean swapping salt for a potassium salt without an assessment. Before using a potassium salt, check with your doctor if you have kidney disease or take medicines that can raise its levels [1].

What mistakes do we see in consultation?

• Compensating with stock cubes or soy sauce. It is the same salt under another name.
• Counting carton vegetable juice as a vegetable. It usually contains added salt.
• Swapping ham for turkey cold cuts. It is leaner, but it also contains added salt.

And the question that comes at the end of the visit: no, this does not replace your medication. Changing what you eat may lead your doctor to review the plan when they see the readings, but adjusting or stopping a drug is their decision.

Three salt-free dinners in under fifteen minutes

All three use foods from the list above, and none needs salt in the pot.

Courgette and onion omelette with salad. Courgette and onion softened slowly in extra virgin olive oil, two eggs and, on the side, tomato with oregano. A well-softened onion sweetens the omelette, and the lack of salt is noticed less.

Rinsed chickpeas with spinach and paprika. A tin of chickpeas drained and rinsed for a minute under the tap, sautéed with spinach, sliced garlic, a little paprika and a drizzle of oil. A quick dinner; check whether pulses suit you if potassium is restricted.

Hake en papillote with vegetables and lemon. A hake fillet on julienne of leek, carrot and courgette, with slices of lemon, dill and oil, sealed in baking paper. Twelve minutes at 200 °C, with no salt and no pan to wash.

If you prefer to have the whole week sorted, with its shopping list, there is the weekly no-added-salt menu for hypertension.