Garlic, Onions and Blood Pressure

Garlic is a perennial herb and a member of the lily family. Its relatives include onions, chives, leeks, autumn crocus, and lily of the valley, among many others.

Garlic, native to Central Asia where it grows wild, has been cultivated all over the world for over five thousand years, making it one of the oldest cultivated plants.

For millennia, garlic has been highly valued in cultures around the world for its culinary and therapeutic virtues. It has been indispensable in Chinese cooking for over four thousand years.

In 3000 B.C.E., the Indian healer Charaka, the father of Ayurvedic medicine, said garlic maintains the ability of blood to flow and strengthens the heart.

In Egypt, laborers who built the pyramids of Cheops in 2800 B.C.E. were given a daily clove of garlic for strength and protection. Six garlic bulbs were found in Tutankhamen’s tomb, which dates from 1300 B.C.E.

The garlic was placed there by his priests either to ward off evil spirits or for him to use on his otherworldly journey. Codex Ebers, an Egyptian medical papyrus written in 1550 B.C.E., gives over eight hundred therapeutic formulas, many of which were either based on or used garlic.

Over one thousand years later, in 450 B.C.E., Hippocrates ranked garlic as one of the most important of his four hundred “simples,” or therapeutic remedies. Long before processed food, 2 to 5 percent of the people in any society developed high blood pressure.

People who develop high blood pressure have minor but perceptible symptoms, with headaches and nosebleeds being the most common. High blood pressure also leads to heart disease, kidney failure, and visual problems.

So even though doctors didn’t routinely measure blood pressure until this century, people have long recognized the symptoms of high blood pressure. These symptoms were usually called “hot blood.” Folk remedies to cure hot blood included garlic.

In the twentieth century, scientists have identified some of garlic’s active chemical components, confirming the accuracy of this folklore. In 1921, Dr. Michael Leoper published a paper discussing the blood-pressure-lowering effects of a garlic extract.

It not only lowered blood pressure, but it relieved symptoms, such as headaches, dizziness, and occasional nosebleeds. Garlic lowers blood pressure by causing the blood vessel walls to relax and dilate, reducing resistance to blood flow, or peripheral resistance.

In 1985, Dr. Ed Block identified ajoene, a material in garlic responsible for lowering blood pressure. He confirmed his findings by making the same material in the lab and testing it on people with high blood pressure. His findings have been expanded since then.

Active components in garlic also cause the kidneys to reduce their output of high-blood-pressure-causing hormones. In addition, garlic is a mild diuretic, which causes the kidneys to relax their reabsorption of salt and produce more urine.

As they produce more urine, they release more salt, and this reduces blood pressure. Potassium, a second and necessary mineral, is also released, but because garlic supplies potassium, it naturally compensates, to some extent, for potassium loss in urine.

Other researchers in 1921 credited the effects of garlic on intestinal putrefaction. If indeed toxins from intestinal microbes have any role in high blood pressure, garlic could be effective because of its antibacterial properties or because it reduces the absorption of the toxins.

The possibility that intestinal microbes can cause high blood pressure is still being researched. Garlic can further benefit people with high blood pressure by reducing platelet aggregation.

When blood components, called platelets, clump together, or aggregate, they form clots, which can cause heart attacks and strokes. Garlic reduces aggregation and helps prevent these internal clots, thus reducing heart attack and stroke risk.

This is particularly important for people with high blood pressure because high blood pressure increases platelet aggregation by a large factor. Garlic can make any dietary program more effective. Its only side effect is a slightly pungent breath.

Compared to most modern medications that produce dizzy spells, blackouts, and loss of sexual ability, a little garlic breath doesn’t seem so bad. Onions, aparagus, leeks, and other members of garlic’s botanical family all contain some allicin, an active ingredient in garlic and its analogs.

They contain these to a lesser extent than does garlic, so they aren’t as effective, but they can still contribute to the overall effect. Add chives to the sour cream on your potatoes, put a slice of onion on your salad, and always add a crushed garlic clove to your pot of soup.

According to the experts, kyolic garlic, aged garlic pressed into tablets and sold in health-food stores, works as well as garlic. At the first international meeting on garlic, papers were presented to show that aged, kyolic garlic has the same properties as fresh, raw garlic bulbs.

There are many garlic tablets sold under many names; some are quite expensive. Because there are no clinical studies on this aspect of garlic tablets, the only advice is to try them and see. However, you should always focus on fresh garlic.


  • Add a clove of garlic to each serving of soup.
  • Add a clove of garlic to a garden salad.
  • Add a clove of garlic to each serving of fish, roast, or fowl.
  • Add a half clove of garlic to each serving of spaghetti sauce.


  • Avoid garlic salt; it’s salt.
  • Avoid garlic oil except in a recipe.
  • Don’t let a day pass without eating some garlic.