On The Shelf

Mickie Cathers

Probably best known for soothing the pain of sunburns, aloe vera is a cactus-like plant favored not just for burns but also for acne, eczema, oral submucous fibrosis, and radiation-induced skin reactions. Aloe vera juice is promoted as a low-calorie drink that clears up skin, relieves constipation, reduces heartburn, and improves eye health. But is aloe really a magic cure-all?

Background and function

This spiny, perennial succulent is a member of the Liliaceae family and grows in dry, hot, subtropical regions. The word “aloe” derives from the Arabic “allaeh,” meaning “shining bitter substance” and “vera” is Latin for “true.” Truly, aloe vera (Aloe barbadensis Miller) has a long history as a universal remedy with far-reaching pharmacological and cosmetic uses. By the early 1800s, aloe was being used as a laxative and was successfully used to treat chronic and severe radiation dermatitis in the 1930s.

Studies investigating the benefits of aloe as a dietary supplement or topical treatment focus on aloe’s active components that serve as antioxidants, laxatives, anti-inflammatories, antiseptics, and analgesics. Aloe boasts a panoply of vitamins (vitamins A, C, E, B12), enzymes (amylase, catalase, and peroxidase), minerals (zinc, copper, selenium, and calcium), sugars (mannose-6-phosphate and glucomannans), anthraquinones (aloin and emodin), fatty acids (lupeol and campesterol), hormones (auxins and gibberellins), and 20 of the 22 amino acids, including 7 out of 8 essential amino acids.

Each triangular, fleshy leaf of the aloe plant contains a clear gel of 99% water along with glucomannans, amino acids, lipids, sterols, and vitamins. The middle layer of latex is the bitter yellow sap and contains anthraquinones and glycosides. It’s these anthraquinones that create aloe’s laxative effect by increasing intestinal water content and peristalsis. Anthraquinones have also been associated with antiviral, antitumor, and anticancer activity. Both the clear gel and yellow latex are widely used in health care products.

Is there a benefit?

Several studies have shown that aloe vera gel can improve skin health and decrease the appearance of fine wrinkles and skin redness by stimulating the fibroblast. Found in the gel of the leaf, glucomannan (a dietary fiber) and gibberellin (a plant hormone) interact with growth factor receptors on the fibroblast, stimulating activity and proliferation, which in turn significantly increases collagen creation.

By increasing collagen, aloe vera not only produces moisturizing and anti-aging effects, but can also accelerate wound contraction and strengthen resulting scar tissue. Aloe’s anti-acne effect is attributed to the amino acids that soften hardened skin cells, and to zinc, which tightens pores.

Aloe’s anti-inflammatory properties are attributed to its ability to inhibit the cyclooxygenase pathway, much like NSAIDs, and reduce prostaglandin E2 production. Aloe also bolsters the immune system by inhibiting the release of reactive oxygen free radicals from activated neutrophils, bolstering the immune system.

Clinical research for topical application of aloe suggests benefits in enhanced healing and reduced pain from burns. Aloe may also be helpful to people with herpes simplex, lichen planus, psoriasis, or acne (in combination with medical soap and tretinoin gel). Aloe vera gel has been found to produce a protective effect against radiation damage to the skin through an antioxidant protein, metallothionein, which is generated by the skin and scavenges hydroxyl radicals.

Many studies have shown the benefits of aloe vera in the prevention and treatment of digestive diseases. Significant clinical evidence demonstrated that a mouthwash and gel made with aloe vera was effective in preventing and treating gingivitis and periodontitis as well as reducing the swelling and postoperative pain after third molar surgery and atraumatic tooth extractions.

While aloe vera gel has been found to provide benefits as a topical ointment or a mouthwash, there is no scientific evidence to support oral ingestion of aloe vera. Trials evaluating aloe vera’s effect on irritable bowel did not show significant benefit over placebo and in 2002, FDA issued a final rule banning the use of aloe as an OTC laxative.

What to tell your patients

Topical use of aloe gel is generally considered safe and can be effective when treating skin conditions although patients with allergies to plants in the Liliaceae family (e.g., lilies and tulips) may be cautioned to apply aloe to a small area first as adverse effects may include redness, burning, and stinging. Also note that the application of aloe to skin may increase the absorption of steroid creams such as hydrocortisone. Be aware that combined use of oral aloe vera and furosemide may increase the risk of potassium depletion and may interact with oral hypoglycemic drugs and insulin by decreasing blood glucose levels. The laxative effect of aloe may cause low potassium levels and electrolyte imbalances.

Oral consumption of aloe gel is possibly safe when used short term. However, aloe latex and whole-leaf extracts should be avoided. Adverse effects include abdominal cramps, diarrhea, red urine, hepatitis, and constipation. Serious adverse effects include kidney damage. Patients should be aware that taking 1 g per day of aloe latex could be fatal. Caution pregnant and breastfeeding patients that oral ingestion of aloe gel or aloe latex may be unsafe. ■