I used a filter coffee machine to prepare a large cup of coffee, made with decaffeinated ground coffee. The process was exactly the same as my experiment to see if caffeine coffee affected bloood pressure, except for the type of coffee, which in that case was obviously a standard caffeine coffee. In the current experiment, the coffee was decaf.

Here are my results:

Here is the data as a graph showing the effect of de-caffeine coffee on blood pressure:

Before drinking the coffee, my blood pressure was fairly stable at around 125/82. However, at 10:31, around 5 minutes after drinking the decaf coffee, my blood pressure fell to 116/78, and fell even further at 10:36 to 112/75.

For 10:31 to 10:50, my blood pressure was below the starting blood pressure of around 125/82. From 10:58 until the end of my experiment, blood pressure had returned to near the starting level.

It appears from these results that drinking the decaffeinated coffee reduced my blood pressure for a period of around 25 minutes before blood pressure returned to normal.

Now, whether this is due to the decaf coffee itself, or some other factor involved remains to be seen. For example, it may well be that the decaf coffee itself has no effect on blood pressure, and something like the heat in the drink was responsible.

As a follow up experiment, I need to drink an equivalent volume of hot water.

That will be my next experiment.

People who have high blood pressure need to watch what they eat. Closely linked to this is exercise, which is also beneficial. However, before changing diet or exercise routines, please consult your doctor to talk through your personal situation.

Causes of hypertension (high blood pressure) in most cases are very difficult to diagnose (in fact some sources suggest that even up to 90% of cases have unknown causes). However, some of the common factors thought to be involved include:

• moderate to excessive alcohol intake
• smoking
• too much caffeine
• being overweight
• too much salt in the diet
• genetics

These factors mean that:

• If you are overweight, try to lose weight. Reducing % body fat can lower blood pressure. A 30 minute walk every day can help you achieve this.
• Try to eat more fruits and vegetables and less processed foods.
• Always look at the nutritional information on the food you buy, and choose those low in salt (or sodium).
• Drink less caffeine drinks. Often fizzy drink contain a lot of caffeine, so do read those labels. Try to switch to decaffeinated coffee if you are a coffee drinker. I actually found I needed a caffeine coffee in the morning so had one caffeine coffee first thing, followed by decaf if I wanted more.
• Reduce alcohol intake to recommended levels or less.
• Stop smoking!

The problem with trying to lower your salt, is that there is so much hidden salt in the stuff you buy at the grocery shop.

Tips to reduce salt in your diet

• By products that are labeled as no salt added.
• By fresh meat and vegetables rather than processed products. Lots of those cold meats at the deli have added salt, as do canned vegetables.
• Try to stop putting salt on food when cooking or eating. You may find that the food becomes “tasteless” when you do this, but after a while you will get use to it.
• When buying bread, look for the sodium levels on the packaging and select the one with the lowest levels. I have found the amounts of sodium in sliced bread varies enormously.
• Cut back on stock cubes and packages soups which are often high in sodium. If you want stock cubes, look for low sodium ones.
• If using canned food, rinse well in water to remove salt. Tinned vegetables and tuna are good examples of foods packages in extra salt.
• Read the labels on breakfast cereals. These often have high levels of salt.

Additional Supplements thought to contribute to lowering blood pressure

Magnesium, potassium and calcium are three very important elements of a diet, and are thought to have blood pressure lowering properties. I have listed below some of the sources of these supplements, but please do consult your doctor before supplementing with these minerals.

Magnesium – dark green leafy vegetables. Soy products, legumes and seeds, nuts (e.g. almonds and cashews), whole grains like brown rice, bananas, dried apricots, and avocados. Your body eliminates excess magnesium.

Potassium – salmon, cod, and sardines. Broccoli, spinach, lettuce, parsley, peas, lima beans, tomatoes, potatoes with skins. Citrus fruits, apples, bananas, and dried apricots. Note people with kidney problems should avoid these foods. They require a low potassium diet.

Calcium – Milk and dairy products such as yogurt and cheeses. However, try to go with low fat products. Skimmed milk has a higher calcium content than full fat milk. Broccoli, kale, and bok choy. Salmon and tinned sardines (eat the bones), shellfish, almonds and Brazil nuts. Also look for products with extra added calcium.

B Vitamins – Broccoli, spinach, wheat germ, bananas, potatoes, chicken, fish, lean meat, milk, liver and eggs.

Omega 3 – Walnuts, oregano, salmon, halibut, shrimps, cod, tuna, scallops, cauliflower, cabbage, broccoli, sprouts, kale, spinach and strawberries. Look out for margarine and dairy drinks with added Omega 3.

The DASH Diet

The DASH Diet puts many of these factors into an easy to follow diet system. You can get a free copy of the Dash Diet from the National Heart, Lung and Blood Institute website. The DASH diet is clinically proven to significantly reduce blood pressure.