Prostaglandins are technically hormones but are seldom classified as such. They belong to a group of lipid compounds that are obtained from fatty acids with important functions in the body.
Prostaglandins are not stored by the body but the cells can produce them on demand when there are available raw materials. Prostaglandins PG2 and PG3 have significant roles with regards to blood pressure.
PG2 is made from either one of the two fatty acids. It can be linoleic acid or arachidonic acid. Linoleic acid is polyunsaturated fat derived from plants while arachidonic acid is from animal meat. Aspirin or indomethacin hampers the production of prostaglandin thereby increasing blood pressure due to increased total peripheral resistance.
PG2 from linoleic acid is responsible in the dilation of peripheral arterioles and make possible the smooth flow of blood in the kidneys. Also, it helps the kidneys in removing sodium from the blood by releasing leukotrienes.
PG3 is composed of eicosapentaenoic acid (EPA) which is an omega-3 fatty acid. EPA is best obtained from blue-skinned cold-water fish like salmon, mackerel and trout but can also be found in the chloroplasts of green plants. It has no influence on the kidneys and peripheral resistance unlike PG2.
However, it acts as natural lubricants in the blood cells and cells in the arteries and arterioles to facilitate the flow of the cells to the vessels and capillaries. Hence, people with plenty of EPA are assured of lower blood pressure. This is maybe one explanation why vegetarians generally have low blood pressure in the absence of significant medical studies.
So, in order to promote normal blood pressure, your diet must contain linoleic acid and sensible amount of EPA. A good diet then must have plenty of vegetables and some cold-water fish. If fish is not taken regularly, fish-oil capsules are available with EPA or flax-oil supplements, a good source of alpha linolenic oil (ALA) which is an omega-3 oil. EPA and flax oil are also good in the reduction of heart disease and cancer of the breast in women.
Additionally, ALA is produced from linoleic acid from the chloroplasts of green plants. People and animals depend on plants for their production since it can not be made by them. For this reason, taking flax-oil supplement is the only way to get ALA.
Flax oil which is rich in ALA, about 52%, is available in bottles in supermarkets which can be added to various foods like oatmeal and salad. Flax oil should not be used in frying or baking to avoid loss of nutritional value.
Further research is still ongoing to find the derivatives needed in order to reduce the blood pressure of people with damaged prostaglandin. As of now, eating food like vegetables and fish with the inclusion of garlic and onion is the natural remedy.