High Blood Pressure and Dietary Supplements

Food supplements are quite literally on everyone's lips-or at least that is what advertising would have us believe. We are constantly being told that we need product X, Y or Z to stay or become healthy, productive, young, beautiful or whatever else.

Effects on certain medical conditions are generally implied rather than openly advertised. Although food supplements resemble medicinal products in their dosage forms, such as capsules, drops, (effervescent) tablets, etc., they are legally classified as foods and must not be intended to alleviate or cure diseases. Of course, they must not have any adverse effects on health either.

However, advertising copy and descriptions suggest that they have such effects. But what is the truth behind these claims? In keeping with our specialist focus on blood pressure, we have taken a closer look at dietary supplements.

First of all, you should ask yourself whether you actually need the supplement. Apart from certain risk groups, it is generally not necessary to supplement your diet. It is far more important to ensure that your diet itself is balanced. Trying to compensate for an unbalanced diet with supplements is unlikely to be effective.

The risk groups mentioned above may include, for example, pregnant women or people with an intestinal disorder who have an increased need for certain nutrients or difficulty obtaining sufficient amounts of them from food. In these cases, supplementation, meaning the targeted addition of nutrients to the diet, will always take place in consultation with the treating physician.

Of course, within the broad field of dietary supplements, some are better researched than others. In general, however, it is striking that the effects that can actually be demonstrated almost always fall far short of the advertising claims. This is especially true of new, recently "hyped" products that claim to have a broad range of effects, covering virtually everything from hair loss to athlete's foot.

CBD products

One example is CBD oil (cannabidiol oil). Although studies are now available, many of them provide little evidence to support the advertising claims. You can find our detailed article on this topic here:
Does CBD or hemp oil help lower high blood pressure?

Ashwagandha

Ashwagandha is another relatively popular example at present. The winter cherry, known from Ayurveda, is said to have significant effects.

However, if you look into it more closely, you will also find various studies that have investigated one effect or another. The best-studied effects are those on sleep and a general stress-regulating effect, although the latter is itself a rather vague term.

On closer examination of the individual studies, the critical reader quickly notices that they have limitations. Most of the studies were conducted over only a short period, and the subjects, if they were humans rather than animals or test tubes, were young and/or healthy.

Under limitations, one often already finds qualifying phrases such as "should be studied further." But indications of possible side effects can also be found after a little searching.

For example, people with cardiovascular disease and those taking blood-thinning medication should consult their doctor before taking ashwagandha.

Potassium

There are a small number of dietary supplements that have actually been relatively well researched, including their effects on blood pressure. However, desired effects are almost always accompanied by an undesirable (side) effect. One example is potassium, which is often promoted as an alternative salt for people with high blood pressure but is not suitable for people with kidney disease, for example.

Zinc

Another example is zinc, which is used not only as an ointment for injuries but also as a dietary supplement in connection with blood pressure. Although there is evidence that zinc deficiency contributes to high blood pressure, the current state of research is not advanced enough to recommend taking it as a dietary supplement.

To date, the studies have been conducted on mice and rats as well as on human blood vessel samples. They aim to investigate zinc's mechanism of action to determine whether it could be a future target for therapies, i.e. medicines, that act on blood vessels.

Zinc is also generally consumed in sufficient amounts through a balanced diet. However, an overdose of zinc, which is classified as a heavy metal, can cause symptoms of poisoning and, for example, impair the body's absorption of copper. A copper deficiency, in turn, can lead to neurological problems and anaemia.

Magnesium

The situation is similar with magnesium. Although there is evidence that a deficiency promotes high blood pressure, this must be confirmed on an individual basis. Studies have shown that magnesium affects blood pressure primarily when a magnesium deficiency is present.

Here too, there is a risk of overdose, with potentially devastating consequences. Excess magnesium can cause paralysis, which may also affect the respiratory muscles, and cardiac arrhythmias that can lead to cardiac arrest.

Therefore, taking dietary supplements should always be discussed with your doctor, especially if you are taking medication. The medication does not necessarily have to have been prescribed for the same condition, as interactions with other medications are also possible. Therefore, when asked about medication use, it is important to mention not only prescribed medicines but also any over-the-counter products and dietary supplements taken "voluntarily."

Dietary supplements as effervescent tablets

Particular care should be taken with dietary supplements administered as effervescent tablets. Due to their high sodium content, they can negatively affect blood pressure. Researchers at Saarland University Hospital discovered this. They examined both over-the-counter and pharmacy-only effervescent dietary supplement tablets and found that they contained an average of 283.9 mg of sodium. The highest level was found in a vitamin C effervescent tablet containing 564.7 mg of sodium, which corresponds to 28% of the recommended maximum daily sodium intake. And that is in a single effervescent tablet. People with hypertension should therefore include any effervescent tablets they take when calculating their daily salt intake.

Overall, most people can obtain all the nutrients they need from food. With a balanced diet, overdoses of individual substances are virtually impossible. This contrasts with dietary supplements, which often lack a reference value for actual individual requirements and in which the units of the active ingredient contained are just as inconsistent as the recommendations for use.

This can easily lead to overdoses. It is often said that any excess is simply excreted again. However, this applies primarily to healthy (!) people. In people with pre-existing conditions, it can lead to metabolic disorders, among other things. Excreting substances taken in excess also places an additional burden on an already damaged kidney, which can worsen an existing kidney condition. People with high blood pressure in particular should be especially careful.

Therefore, talk to your doctor about whether supplementing a particular substance makes sense and is advisable for you. At best, you will merely waste money; at worst, you may even harm your health.

This article is from Tensana – the leading app since 2011, helping hundreds of thousands of people monitor their blood pressure every day. Our content is based on carefully researched, evidence-based data and is continuously updated (as of 01/2026).

Author Sabine Croci is a qualified medical assistant with many years of experience in internal medicine and cardiology practices as well as outpatient care, and has headed the specialist editorial team at Tensana since 2015. Thanks to her extensive additional qualifications as an emergency medical technician, first responder, and in various areas of therapy and emergency care, she provides well-founded, practical, and reliably verified information.