One of the top keywords that bring readers to my blog is “flaxseed.” I’m not surprised, for flaxseed—also called “linseed”—is popular here in North America and elsewhere for its many dietary and medicinal uses. I love to talk about flaxseed! I last mentioned flaxseed in my blog of July 7, 2015, where I described how linseed tea was used in making an emollient clyster (an enema, in other words) for Regency women suffering from childbed fever.

A field of blooming flax (Source: Courtesy of SasFlax, Flax Council of Canada, FC2015 Inc.)

A field of blooming flaxseed (Source: Courtesy of SaskFlax, Flax Council of Canada, FC2015 Inc.)

Today’s blog is built around Dr. Andrew Duncan’s description of common flaxseed in his book The Edinburgh New Dispensatory, published in 1803.1 His book contains an impressive description of the elements of pharmaceutical chemistry, such as the properties of oxygen, sulfur and arsenic; it includes the Materia Medica, which is a collection of the therapeutic properties of materials used in medicines and the healing arts; and it provides a list of the pharmaceutical preparations that were needed by apothecaries, doctors and surgeons treating patients during the Regency era.

Let’s look at each of Dr. Duncan’s comments about flaxseed. For fun, a copy of his original text is shown below. It gives you a feel for what it’s like to read Regency-era text where the “long s” —looking for all the world like an “f” character—is used. For example, the word “expressed” on line five looks like “expreffed” and the word that looks like “feed” is actually “seed.” Don’t let it give you a headache!

Description of flax from the Edinburgh New Dispensatory 1803

Description of LINUM (flaxseed or linseed) from the Edinburgh New Dispensatory, 1803

Species: Linum Usitatissimum

Duncan first describes the flaxseed plant, writing: Semen, ejusque oleum fixed. (Ed.) This Latin expression is translated roughly as “seed, [and] its fixed oil.” Today we say that the species Linum usitatissimum is a member of the genus Linum in the family Linaceae. The Ed. designation denotes the materia medica found in the Edinburgh Pharmacopoeia published in 1803. The Lond. Ed. notation refers to the London Pharmacopoeia (1791 edition).

Here’s what’s missing from Duncan’s description: flaxseed or linseed is classified as an oilseed, not a grain like wheat, oats and rice. Here is its overall composition: 41% fat, 20% protein, 28% total dietary fiber, 7.7% moisture, and 3.4% ash.2 (Ash is the mineral-rich material left over after a sample is burned.) Flaxseed is also gluten free.

Historical Uses of Flaxseed

The ancient use of flaxseed in Egypt is noted in Duncan’s second paragraph, along with information that the plant grows wild in the south of England and in Europe. In truth, flaxseed is considered a founding crop, meaning that it was among the first plants to be domesticated.3 Wild flax was likely first cultivated around 8,000 BCE (Before the Common Era) or about 10,000 years ago in the so-called Fertile Crescent, a region that today encompasses several countries, including Iraq, Kuwait and portions of Iran and Turkey, among others. Many early farming societies flourished in its fertile valleys.

Roughly 8,000 to 9,000 years ago the process for making flax into linen was developed. Some 3,500 years ago Egyptians began making linen clothing from flax fibers and using flax oil for embalming. About 2500 years ago medical practitioners used flax as a laxative and added it to poultices to heal sores and lacerations. By the 15th century of the current era, flaxseed (linseed) oil was being used to preserve Renaissance paintings. Beginning in about 1995, flaxseed became recognized as a functional food.3

Farmland flaxseed cookies (Source: Courtesy of SasFlax, Flax Council of Canada, FC2015, Inc.)

Farmland flaxseed cookies (Source: Courtesy of SaskFlax, Flax Council of Canada, FC2015, Inc.)

Flaxseed Is a Functional Food

Flaxseed contains nutrients and other compounds that have important health benefits. Among these are the following:

  • alpha-linolenic acid (ALA, for short), which is the true essential omega-3 fatty acid, being required in the human diet because our bodies can’t make it. (Our bodies can make the long-chain omega-3 fatty acids EPA and DHA from ALA.) Diets high in omega-3 fatty acids from all sources, including flaxseed, result in a lower risk of chronic diseases like heart disease, cancer and arthritis. Check out this review of omega-3 fats and this review of the importance of omega-3 fats in the human diet.
  • lignans are phytoestrogens—that is, they are plant chemicals that can have effects similar to those of the hormone estrogen in both humans and animals. Flaxseed is one of the richest sources of lignans, which have been shown to have antioxidant and anticancer effects. You might enjoy reading this summary of flaxseed lignans.
  • dietary fiber, of which flaxseed contains both insoluble dietary fiber (what your grandmother called “roughage”) and soluble dietary fiber, which includes mucilage gums like those found in flaxseed. Soluble fiber promotes bowel health and helps reduce the risk of heart disease and colon cancer. If you have a burning desire to read more about dietary fiber, try this article by Dr. Joanne Slavin or this one by Lattimer and Haub.

Mucilage and Oil Content of Flaxseed

Duncan writes that “linseed contains about one-fifth of mucilage, and one-sixth of fixed oil.”1 Here I must assume (always a dangerous thing to do) that the composition is based on weight, which is typical of most chemical analyses. Thus, Duncan’s figure for the mucilage content of flax is a little high at 20% (1/5 of the seed weight), while his figure for the oil content is low at ~16% (1/6 of the seed weight). Here’s what we know today, based on our more sophisticated methods of analysis:

  • Mucilage gums in flax constitute about 8% of the seed weight. The amount of mucilage gums found in flaxseed can vary, depending on how it’s extracted. It also differs among the various cultivars of flax.3 (Cultivars are different varieties of plants developed in cultivation by selective breeding.)4
  • The oil content of flaxseed is about 40-45% on a dry weight basis.5 The material left over after the oil is expressed is called flaxseed meal (or linseed meal), which is described in the section below on flaxseed oil-seed cake.

Mucilage Is (Not) Found in the Skin

“The mucilage resides entirely in the skin,” writes Duncan. Not true! The mucilage component of flax is not found in the “skin” but sits right on the surface of the seed coat. When whole flaxseeds are placed in water or some other liquid, the mucilage floats off the seed skin and makes the liquid viscous or gummy. Hence: flax tea. Make a pot of flax tea by pouring ten to twelve ounces of boiling water over whole flaxseeds. Allow to steep for several hours or overnight, pour off the gummy water and discard the soft seeds (or use them in soup). The mucilage gums in flax tea help promote bowel health.

Flax Oil Is Separated by Expression

In paragraph five Duncan makes only one statement that holds true today: “The oil is separated by expression.” Today many manufacturers use a cold-press process to keep flax oil as fresh as possible.

Duncan’s other comments about about flax oil are false. In today’s vegetable oil market, some oils like corn, canola and soybean are often cheaper than specialty oils like olive, walnut and flax. Flaxseed oil is sold in health food stores, some supermarkets and online. And flax oil is not “rancid and nauseous, and unfit for internal use” (as we shall see in an upcoming blog).

Flax Oil-Seed Cake

Duncan wrote that the cake remaining after the oil is expressed is used as animal feed. Some 200 years later, it’s still the case! Today linseed meal (what Duncan calls an “oil-seed cake”) is used in livestock and animal feeds, mainly for horses, cattle and broilers. Laying hens are fed a diet containing flaxseed meal to increase the omega-3 fat content of their eggs. In fact, eggs derived from hens fed flaxseed meal contain significantly more ALA and DHA compared with regular eggs. The meal itself contains about 5% oil, 30% protein and 10% fiber, along with vitamins and minerals. More information about flaxseed meal can be found in this guide for the animal feed industry.

How Much Did Dr. Duncan Get Right?

Much of Dr. Duncan’s description of flaxseed was accurate. His comments about the location of the mucilage gums and the oil content of flaxseed are off, which is only to be expected, given the relatively crude analytical procedures available in 1803.

His most egregious statement is that flax oil is “rancid and nauseous, and unfit for internal use.” In fairness, he lived in an era with almost no refrigeration. Thus any flax oil produced by crushing flaxseeds likely became unsavory fairly quickly, especially during the summer months. Today flaxseed oil is a popular dietary supplement and many research studies have revealed its health benefits, some of which I will examine in my next blog.


1Duncan, Andrew. The Edinburgh New Dispensatory (Dublin: Bell & Bradfute, 1803, p. 249 (PDF p. 280).

2Morris, DH. Flax: A Health and Nutrition Primer. Winnipeg: Flax Council of Canada, 4th ed., 2007, p. 10. Also available online here. (The file can be downloaded as a PDF.)

3Vaisey-Genser, Marion and Morris, Diane H. History of the cultivation and uses of flaxseed. In: Flax: The Genus Linum. Muir AD and Westcott ND, eds. New York: Taylor & Francis, 2003, pp. 1-21.

4Daun JK, Barthet VJ, Chronik TL, Duguid A. Structure, composition, and variety development of flaxseed. In: Flaxseed in Human Nutrition, 2nd ed. Thompson LU and Cunnane SC, eds. Champaign: AOCS Press, 2003, p. 15.

5Ibid., p. 5.