Purslane, the Omega-3 Champion of Leafy Vegetables

Common purslane (Portulaca oleraceae) is a fleshy-leafed creeping plant that grows wild all over the United States and in many other countries. The potograph below shows it growing on a narrow strip of soil by a parking lot. Many people consider purslane a weed, and the Internet has many sites dedicated to its extermination, as the following link attests.

However, this humble plant has the highest level of alpha-linolenic acid of any leafy green. Alpha-linolenic acid is an omega-3 fatty acid, one of the fatty acids essential for human nutrition. I first saw purslane mentioned in the book: The Modern Nutritional Diseases and How to Prevent Them, by Alice and Fred Ottoboni. This book, written by two health scientists concerned about their own health, offers lots of well-referenced information about our modern diet, and how the excessive consumption of carbohydrates may be leading to the epidemic of degenerative diseases we are experiencing as a population, including heart disease, obesity and diabetes. It goes into some detail on the metabolism of all the major nutrients (fats, carbohydrates and proteins), and makes recommendations for healthier living. Eating purslane is one of those recommendations.

Although I was tempted to eat the purslane I found growing so nearby, a lot of people walk their dogs in that area, so I decided to look for it in stores. I had no luck at my local supermarkets, but was able to find seeds for Golden Purslane online. I don't know if the nutritional profile is the same for these two varieties, but the picture on Amazon.com looked very close to what I had seen outside. The seeds are very small, smaller than poppy seeds. I added some to a planter on my windowsill and two days later I was rewarded with lots of little seedlings. They have not grown very vigorously, that windowsill is probably not getting enough direct sunlight. However, some of them have "taken", and are getting bigger slowly. They form taproots, and I'll give them the time to establish themselves before I harvest. You can see them here growing, and also compare the plants I found outside to the ones I planted. The largest of the seedlings shown in the picture are about two months old. I bet if you give yours plenty of sun you will get much faster growth

Another book in which you can find useful information about purslane is "The Omega Diet", by Artemis Simopoulos and Jo Robinson. They go into a lot more detail about the plant and its health benefits. The first edition of this book was printed in 1999, so these authors can be considered some of the earliest to draw our attention to purslane. The book mentions many other sources of Omega-3 fatty acids, as used in the Mediterranean diet.  

Purslane is not only rich in omega-3 fatty acids, but also in vitamin C and vitamin E. In fact, in these three nutrients it compares favorably to spinach. Maybe Popeye should take note! The same Simopoulos I talked about earlier mentions in an abstract published in the Journal of the American College of Nutrition that 100 grams of purslane contain 300-400 mg of alpha-linolenic acid (ALA), one of the omega-3 fatty acids.

The omega-3 fatty acids found in higher plants are not the same ones as in fish, other animals and in our own cell membranes. The alpha linolenic acid found in purslane, spinach, flax and other plants only has 18 carbon atoms, while the omega-3's found in fish oil have 20 (EPA: eicosapentaenoic acid) or 22 (DHA: docosahexenoic acid) carbons. In our bodies, one is converted to the other by the enzymatic addition of two carbon atoms at a time. This conversion process is not very efficient, so one needs to consume a lot of alpha linolenic acid to reach the acceptable intake (A.I.) of EPA and DHA (Wikipedia). The Ottoboni book has a nice little table comparing the fatty acid content of fish oil and flax oil in chapter 7.

According to Wikipedia, purslane also has 0.01 mg per gram of eicopentanoic acid (EPA), which is not present at all in flax oil. This would make 1 mg of EPA for a 100 g portion of purslane, 10 mg for a kilogram (2.2 pounds) and 1 gram for 100 kilograms (220 pounds). Very little compared to what you can get from fish oil (1 gram of fish oil has 120 mg of EPA). At these concentrations purslane is unfortunately not a practical source of EPA.  It would be interesting to investigate if it is possible to improve these yields by changes in the plant's environment and selective breeding.

Below you can find the links to the Simopoulos abstract and the Wikipedia article mentioned in the last two paragraphs.

All these sources also stress the importance of establishing the correct ratio of omega-3 to omega-6 fatty acids. Omega-6 fatty acids are also essential fatty acids, but because our diet includes so many products derived from corn, which has predominantly omega-6 fatty acids in its oil, our consumption is heavily skewed toward the Omega-6 fatty acids. This point is beautifully illustrated in Michael Pollan's book: The omnivore's dilemma. He traces the increase in the use of corn products in our society through the past century, from high fructose corn syrup used to sweeten beverages to the use of corn in cattle feed. I didn't get this book in written form, but instead got it from Audible.com. It is narrated by Scott Brick, who is one of my favorite narrators in audiobooks. Omega-6 fatty acids compete for the same enzymes in the conversion process from 18-carbon fatty acids to 20 and 22-carbon fatty acids, and thus decrease the efficiency of conversion from ALA to EPA and DHA.

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If you've read this far, hopefully you are ready to give purslane a try. Please check the following link for some recipes that use it.  Bon Appetit!