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Aloe
History and Folklore
This succulent member of the lily family has distinctive, fleshy, “lanceolate” leaves, which is a botanist’s special way of telling you that the leaves are shaped like lances. After accumulating excess experience with their pointy ends, I quarantined my own Aloe outdoors from my small apartment. It rapidly grew larger than a toddler. That my own Aloe grew to threatening proportions is significant-Aloe almost thrives on neglect.
Though Aloe flourishes in the most barren soils, it is a native of the wetter tropics of Africa and Southern India. Despite its spiny form, it is not a cactus, nor is it the same as the American agaves, which it resembles. It is also confused with an unrelated incense mentioned in the Bible that is more properly called Aloe wood, or lignAloe.
The Bible’s reference to Aloe is questionable, but the ancient Sumerians, Greeks, Romans, and Egyptians used it. Aloe is frequently noted as the legendary skin treatment for Cleopatra, and Aloe gel may indeed help maintain a healthy complexion.
Aloe is one of the most popular herbs. Despite this, most people are not informed that two entirely different products are made from this plant, the gel and the Latex. (“Latex,” in this context, is a botanical term, and should not be confused with the commercial rubber latex.) The gel is a clear, gooey mucilage, obtained from the insides of the leaves, and is most often used for topical skin repair. The latex, on the other hand, is a bitter yellow liquid secreted by cells just beneath the rind of the leaf, and is often dried to make a product that is also confusingly called Aloe, and may be reconstituted with water as Aloe “juice.” To further obfuscate matters, the gel is also sometimes thinned down with water, which is used as a beVerage and is then also confusingly called “juice.” The latex has quite different properties than the gel, when taken internally. Aloe latex is often called a “natural laxative,” and it is-in the same sense that a hurricane is a natural building renovator.
How Scientists Think Aloe Gel Works
Aloe gel’s polysaccharides keep your wounds moist by absorbing water like a sponge. The reason for Aloe gel’s snotty texture, as well as for many other snotty things in life, lies in its polysaccharides. Polysaccharides are large chains of small, ring shaped sugars bonded together like beads on a chain. Sugars of all kinds, including those that make up Aloe gel’s predominant polysaccharide, acemannnan, attract water.
When sugars are small, simple molecules like those in table sugar crystals, they dissolve in water. When the sugars occur in a polysaccharide’s chains, like acemannan, however, the chains are too large to be surrounded and separated by tiny water molecules, so they can’t dissolve like table sugar. But water sticks to these chains, and the chains stick to one another, and this network of chains swells with water. This forms a gooey gel. This gel is similar to what you get if you soak rice, potatoes, or paper in water. Starch, found in grains and potatoes, and cellulose, a component of paper, are also polysaccharide chains, and if you soak them in water, they will swell just like acemannan and ultimately form a gooey pulp, too. Aloe gel is like this-a natural water-retaining sponge.
For many simple wounds and light burns, moisture speeds healing. Dry wounds get crusty, and any living cells in them shrivel up and die. That can be alright in some cases, because underlying tissues just seal themselves off from this arid wasteland and continue living. But processes required for repair must take place in a fluid environment, because particles can move and do things in a fluid. Dryness prevents particle motion. Water gives a wound’s particles mobility. So water’s tendency to cling to Aloe gel probably helps accelerate wound mending.
Aloe gel recruits your white blood cell; they can help heal you, but can also cause irritating inflammation. If you are allergic to pollen, you already know that plants “stimulate” your immune system. Some people’s immune systems are more susceptible to being duped into this inflammatory overreacting. Aloe gel’s acemannan does stimulate the immune system, attracting and activating your white blood cells to the site of application.
White blood cells repair and defend your tissues, but can also damage them with inflammation. So the recruitment of white blood cells could be good for some cases but bad for others. This pro-inflammatory action could even account for a few negative reports following the use of Aloe gel, like itching, redness, delayed healing, and allergic responses. These negative results are fortunately not as common as positive ones, which include reports of accelerated wound repair after Aloe gel is applied. You should be aware that the gel could cause adverse affects, however, so a small test patch might be warranted before committing it to liberal use, especially if you are prone to allergies.
Beta-sitosterol from Aloe gel gets your blood vessels to grow faster, which speeds healing. Beta-sitosterol is found in a wide variety of plants and is more commonly regarded by scientists as an effective cholesterol-lowering agent. But a couple of animal studies suggest it also stimulates the growth of new capillaries, a process called angiogenesis. Three studies link Aloe gel’s beta-sitosterol to angiogenesis, and all but your most superficial wounds require angiogenesis to heal. Not only do your preexisting, broken blood vessels need to mend, but also new blood vessels supply nutrients that support cellular mending activities.
One of Aloe gel’s glycoproteins breaks down your bradykinin, which would otherwise cause swelling, cramps, and enhanced pain perception. Other commonly cited active ingredients of Aloe gel are some of its glycoproteins. One glycoprotein from Aloe gel apparently breaks down bradykinin. Bradykinin is a chain of amino acids that stimulates the widening of blood vessels, or vasodilation. When blood vessels dilate, they leak fluid, and surrounding tissues become swollen. Bradykinin also causes involuntary muscle contractions that, when painful, are called “cramps.” And as if that were not enough, in addition to causing swelling and cramps, bradykinin enhances your perception of pain. Aloe’s degradation of bradykinin, then, may explain why Aloe gel can reduce our pain and swelling.
Aloe gel inhibits the formation of damaging free radicals. In other research, an Aloe gel glycoprotein inhibited the formation of superoxide, a free radical. This positive effect was corroborated by another study, which found that a water based Aloe gel extract inhibits white blood cells creation of oxygen-containing free radicals. Free radical’s damage tissues, and though white blood cells protect us by flinging free radicals at foreign invaders such as bacteria, free radicals can damage your own tissues, too. Aloe gel’s inhibition of free radical formation may therefore lessen your own “friendly fire.” This could help mitigate the free radicals formed by recruitment of white blood cells mentioned above.
Aloe gel inhibits COX-2, giving it an aspirin-like effect. In one study, a glycoprotein from Aloe gel inhibited the cyclooxygenase-2 (COX-2) enzyme, which is how painkillers like aspirin work. A second study confirms that a water-based extract of Aloe gel inhibits COX-2. COX-2 accelerates the production of painful molecules called prostaglandins during inflammation. Anti-inflammatories like aspirin also work by inhibiting this enzyme.
Aloe gel reduces blood clots. The same glycoprotein that inhibits COX-2 also reduces the concentration of another enzyme (thromboxane A2 synthase), which makes thromboxane. Thromboxanes are made by blood platelets and cause blood clotting. Thromboxane lessens your blood loss, but it can also restrict oxygenated blood flow to damaged tissues, a negative phenomenon called ischemia. Although you might conclude that you want thromboxanes to stop your bleeding, thromboxane formation is more commonly thought to cause injury through ischemia. Decreasing thromboxane formation is actually associated with a positive outcome for wound repair. Aloe’s anti-thromboxane activity could hasten your healing.
How scientists think Aloe latex works
Aloe latex contains laxatives. These colorful plant pigments, anthraquinones and anthrones, are collectively called anthranoid laxatives. They may remain in some incompletely purified Aloe gel preparations as well, so if you take the gel internally you still might want to be wary of their effects.
Anthranoid laxatives are found in other, unrelated plants, and act the same way. You can find them in senna, cascara, rhubarb root, buckthorn, and frangula. If you take any one of those herbs, you will notice an effect very similar to your taking Aloe latex. This discussion therefore applies to these herbs as well.
For the active ingredients to work, they must be liberated from attached sugars by your intestinal bacteria. The anthranoid laxatives in these plants usually have sugars attached to them, and the general term for a molecule that has attached sugar is a glycoside. Glycosides are very common in plants. The active ingredients of many plants are often less effective when in the glycoside form, and anthranoid glycosides are no exception. The sugar must be removed by your gut bacteria to liberate the active aglycone, the general term for any former glycoside that has had its sugar disconnected. Therefore, if you expect these plant anthranoid laxatives to work, you ought to have working gut bacteria that can free the active ingredient, the aglycone, from its attached sugar. If you are taking antibiotics or some other factor causes you to have compromised gut bacteria, you might not get the same action.
Anthranoid laxatives reverse the normal direction of the flow of water from your colon to your blood stream. The cells of your colon normally push charged particles called ions from the interior of the colon out into your bloodstream, which eventually reach your blood through capillaries surrounding the colon. When things flow in this direction, it is called absorption. Water follows this parade of ions, because ions have charges, and water loves anything with a charge. Your absorption of water keeps you hydrated. Anthranoid laxatives reverse this flow.
Specifically, anthranoid laxatives appear to open chloride ion channels, such that chloride flows into the colon, a direction opposite its normal route. Positively charged sodium ions may be expected to follow the negatively charged chloride ions, as opposite charges attract. Water always follows ions, so the colon fills with water, producing a watery diarrhea.
Anthranoid laxatives also stimulate production of a prostaglandin, causing gut contractions. This speeds your gut’s contents on a one-way trip. Overly forceful, involuntary contractions are painful and better known as “cramps.” That Aloe’s action is inhibited by anti-inflammatories (like indomethacin) suggests some inflammatory process mediates it. The details are not entirely clear, but anthranoid laxatives do cause more nitric oxide to form in the colon. Nitric oxide, in turn, stimulates the synthesis of a prostaglandin, (PGE2), an inflammatory molecule. Although PGE2 can stimulate processes that protect your stomach lining, such as decreasing acid and increasing protective mucous secretion, in your colon it has a different action, making your colon muscles jump around unpleasantly. This gives you cramps and diarrhea.
Aloe latex kills some of your colon cells, but at least they die a clean death. For some reason, chronic use of anthranoid laxatives is associated with colon cells committing suicide, or “apoptosis.” Apoptosis is a tidy sort of cell death that does not incite inflammation and is generally benign. Cancer researchers tend to perk their ears up when apoptosis is discussed. Since stimulating apoptosis of cancer cells interests them, Aloe latex has been proposed for use against colon cancer, but so far not enough research has been performed to validate this suggestion.
Like Aloe gel, Aloe latex recruits and activates immune cells. This is both good and bad. Aloe latex increases some of your cytokines, which attract and activate white blood cells. If you take anthranoid laxatives, immune cells will be recruited to your colon. But what do they do there? After people take anthranoid laxatives, these white blood cells are then observed dining on the remains of their suicidal colon cells-that is, the colon cells that have undergone apotosis. They also eat up and metabolize the colorful anthranoid laxative molecules, too. So on the one hand, these white blood cells seem to be cleaning up some of the mess that the anthranoid laxatives created. On the other hand, immune cells can irritate and damage an area through inflammation if they get overly aggressive.
If you take a lot of anthranoid laxatives, you will get a strangely polka-dotted colon. White blood cells recruited to the colon by Aloe latex contain a dark pigment, and chronic abuse of anthraanoid laxatives causes “melanosis coli,” a condition in which infiltrated white blood cells are seen as dark spots in the colon. The pigment they contain is actually the partially digested remains of the anthranoid laxatives, which are highly colored as well. The term “melanosis” is misleading, because the pigment they contain is lipofucsin, not melanin, so sometimes you will hear the condition called pseudomelanosis coli. A polka-dotted colon might raise your gastroenterologist’s eyebrows during a colonscopy, but most researchers say that the condition is benign. Although many have searched for a link between melaosis coli and cancer, the association currently remains ambiguous. Melanosis coli might worsen constipation, if severe. The spots do go away over time if the laxative use is halted.
Anthranoid laxatives generate damaging free radicals. While Aloe gel contains free radical scavenging properties, anthranoid laxatives in the latex have the opposite effect: free radical production. Free radicals can damage your DNA, causing cancer, but anthranoid laxatives epidemiological link to cancer currently remains equivocal. That they cause painful cramps and violent diarrhea probably serves as the best reason to avoid use of plant anthraquinones as laxatives.
Aloe gel is also commonly used internally for ulcers, but this use requires more scientific validation. Although anecdotal testimonials for Aloe gel’s internal benefit for ulcers abound, research substantiating these allegations is scarce. The gel occasionally causes severe stomach cramps. It is not known if some component of the gel causes this, but if anthranoids from the latex contaminate the gel, diarrhea and cramps may be expected.
Resource: Herbs Demystified by Holly Phaneuf, PhD
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Natural Health Hut
