About 25% of the global population has high blood pressure (hypertension). It’s incredibly common, especially as we age. A cohort study called The Framingham Heart Study recruited 1,300 participants aged 55-65 years without hypertension and followed them up. The investigators found that the lifetime risk of developing hypertension was 90%! So there’s a good chance that most of us are going to find our blood pressure creeping up over time.
So what can you do about it?
Now most people know that reducing salt (and reducing weight if clinically indicated) can help lower blood pressure, but is there anything else you can do?
Yes! Major trials on diet and blood pressure have aimed to tease out what a blood pressure-lowering diet should look like. Many of these trials (eg the Dietary Approaches to Stop Hypertension (DASH) diet) tried different mixes of foods and nutrients, but when tested individually, some of these foods and nutrients had no effect. So it has been a challenge to nail it down to just one thing, but basically we know the following:
Get loads of plant-based foods - these almost certainly work via a variety of mechanisms driven in part by their fibre, potassium, calcium and magnesium content - not to mention phytonutrients.
Replace processed carbs with either protein or healthy fats. This one often surprises people, but the OmniHeart trial provided good evidence that (in the context of a diet which was low in saturated fat, sodium, rich in fruits/veges, with minerals at recommended levels) replacing 10%kcal of carbohydrate with 10%kcal of protein (half of which was from plants) or 10%kcal fat (most of which was monounsaturated) lowers blood pressure. It’s not clear whether it was the reduction in carbohydrate, or increase in protein or certain types of fat which was the “effective” ingredient, but at least we know this dietary pattern is useful!
I just want to emphasise two things about the OmniHeart trial. Firstly, the control diet was already healthy (low in sodium, high in fruits/veg etc) in this study - so the fact that the simple switch from carb to protein/fat had additional blood pressure lowering effects is the reason I think this trial gives actionable evidence. But also note, high-protein, reduced-carb diets which are not also low in sodium, low in saturated fat and plant-based do not cause reductions in blood pressure in other trials. (I don’t know the reason high-protein might work in one context but not in another - maybe there is an interaction?). So, if people want to try the OmniHeart approach: make it plant-based, low-sodium and limit saturated fat.
How can you incorporate these findings into your own diets?
Try the following tips:
Take every opportunity to add more fruit or veges to your brekkie!:
asparagus, mushrooms, tomatoes, spinach etc with a cooked breakfast.
fruits on cereal, yogurt or even as an accompaniment to a cooked breakfast.
Make up a home-made granola with bran flakes, shaved almonds, seeds, dried fruit, fried coconut and have milk with a decent protein content (dairy/soy).
Instead of having two slices of toast and one egg, have one slice of toast and two eggs.
Or instead of having two slices of toast and one egg, have one slice of toast, one egg, and 2 tablespoons of beans.
If you get hungry, snack on nuts, seeds or fruit.
Yogurts are also a great snack or basis for a healthy dessert.
Make a filling salad main by adding a pulse (eg butter beans/chickpeas/lentils), and tofu/eggs/chicken, plus a high-unsaturated fat oil - rapeseed, olive, avocado, nut).
Take every opportunity to add more fruit or veges to your lunch!:
Add a side salad to any meal if this suits.
Add any vege to a hot meal if it works:
eg for spag bol, make half the plate veges - bell peppers, courgettes (zucchini), aubergine (eggplant), onions…
for stir fry-type dishes, replace half the rice/noodles with edamame beans/chickpeas.
Have fruit for dessert.
Minimise the processed carb, and maximise the protein/healthy fat part of a lunch:
Choose a lean protein main, and make the rest of the meal plant-based: eg instead of chicken and loads of rice, have chicken and a pulse/legume with veges.
Choose an open sandwich and pile high with protein and salad.
Naked burritos (with loads of guac and vege sides) can be a great choice. Add fruit as dessert!
Choose pulse/legume-based mains (eg curries and stir-fries etc) - many of these will have 4-5 different plant-based foods in them.
When planning a main fill the plate with veges first - aim for half the plate.
If you like carbs, aim for the most slowly digested and highest fibre types as often as you can: eg brown rice, whole oats, millet, faro, barley, quinoa, buckwheat.
Legume-based pastas are your new friend:
They are high-protein, low-carb (and made from legumes……) - don’t forget to serve with loads of veges, a drizzle of olive oil etc.
Anything else?
You might wonder why I haven’t mentioned things like dairy, omega-3, and mineral supplements like calcium and magnesium. It’s worth mentioning that calcium, magnesium and potassium each seem important independently: BUT dairy products (which are high in each of these) do not appear to lower blood pressure either in trials, in or high-quality cohort studies. So despite dairy being part of the DASH diet, it doesn’t seem like it’s a *necessary* part of a blood pressure lowering diet. The reason I haven’t recommended mineral supplements is because most people can get enough from food - and plus the foods themselves probably contain a bunch of other beneficial compounds.
There’s also been some fairly high-profile work done on omega-3 fatty acids: a meta-analysis showed that about 2-3g/day of omega-3 fatty acids could lower systolic and diastolic blood pressure by about 2-3mm Hg. This is a pretty modest reduction - for example a low sodium DASH diet compared to a high sodium control diet lowers systolic blood pressure between 7 and 11 mm Hg. There are also limitations to the omega-3 studies, including a lack of clarity on whether the source of omega-3 matters. It’s important to note that omega-3 supplements you buy over the counter are not regulated - and therefore come with risks associated. Omega-3 can be prescribed, but this is only ever done where there is good evidence of effectiveness. Right now the evidence for omega-3 and blood pressure does not meet that threshold. Therefore the best advice is get omega-3 from foods as part of the DASH, high-protein/reduced-carb, Med-style dietary patterns which have good evidence behind them for overall reduced CVD risk. For vegans, getting omega-3 indirectly from ground linseed, chia seeds, hemp seeds and walnuts is an option (I will do a post on vegan nutrition soon).
Also note, your diet doesn’t need to be low-fat to lower blood pressure. A study comparing a high-fat dairy version of DASH to a low-fat dairy version of DASH found the effect on blood pressure was not changed. BUT only the low-fat dairy version of DASH significantly lowered LDL-cholesterol and apolipoprotein a. So to get the full CVD benefits of a blood pressure lowering diet - it makes sense to limit high-fat dairy and base your diet mostly on foods which are predominantly monounsaturated and polyunsaturated: nuts, seeds, plant-based oils (except coconut and palm), avocado, oily fish.
And finally, let me finish another post talking about exercise: it lowers blood pressure too, so do any that you enjoy and probably the more the better!
Your work is priceless! Just incredibly valuable information!
I'm so super grateful to have access to you!
Excellent article. What if I'm also diabetic? What's the best diet pattern to beat both?