About Botanical Oils
The use of botanical oils can be traced back thousands of years, with roots in cultures as diverse as the ancient Sumerians, Chinese and Roman Empire. Botanical oils are prepared from whole plant, preserving its scent, main active ingredients, and the essence of the plant. Botanical oils made from various plants have been used throughout history to honor gods, prepare bodies for funerals, preserve beauty, assist with hygiene and treat a wide variety of medical conditions. Instructions for the preparation and use of plants as medicine is catalogued in the works of Dioscorides, De materia medica, back in the first century.
Modern technology has allowed the active parts of plants to be identified and studied for their role in health and their usefulness against various medical conditions. The value of botanical oils has stood the test of time.
The Properties of Lemon
From India to Italy, the importance of citrus trees touches every continent and crosses from the kitchen table to medicine cabinet. The oldest citrus trees grew in Asia and the modern lemon was actually created by a series of hybridizations of citron and sour orange, possibly in India. By the 1st century AD, lemons had arrived in Italy and were featured in Roman mosaics of North Africa. Their cultivation was described in Qustus al-Rumi’s Arabic treatise on farming in the 10th century, and the Cantonese recorded the lemon’s uses in the 12th century. The personal physician to Muslim leader Saladin wrote a treatise on the lemon at the end of the 12th century. In spite of the nickname “limeys” by which they came to be known, the British navy used sweet lemons, not limes, to combat scurvy at sea in the 18th century.
Christopher Columbus brought the first lemon seeds to Hispaniola in 1493, and Spaniard explorers brought them to St. Augustine, Florida. Today, most of the world’s supply of lemons is grown in Italy and California.
Types of Lemons
The lemon was born a hybrid, and it continues to evolve. The lemon you are most likely to purchase at a grocery store is the Meyer lemon, which is prized for its versatility in cooking. There are approximately 17 recognized varieties of lemon, whose Latin name is Citrus Limon. While much of the literature on the uses of lemons fails to designate the species being used, there is a growing interest in establishing the purity and origin of certain lemon species, which conditions optimize the valuable oil gotten in the extraction process and which are most potent medicinally.
The lemon’s extreme sourness is taken in small doses, but that small dose comes loaded with nutrients. Low in calories, the lemon is twice as rich in Vitamin C as oranges and contains a very high amount of potassium. Lemons also contain bioflavonoids and anti-oxidants such as beta-cryptoxanthin and lutein and zeaxanthin. Vitamins A, B1, B2, B3, B5, B6, Folate and Calcium are all present as well.
The peel of the lemon is also nutritionally valuable. Just 1 tablespoon of the peel contains 9.6mg of potassium, 8mg of calcium, 7.7mg of Vitamin C and 0.6g of fiber. The peel also contains magnesium, phosphorus, plant sterols and essential fatty acids. It is most valued for its flavonoids, which have strong anti-oxidant properties.
Lemon Oil Preparation
The essential oils of the lemon are taken from the bright yellow peel. This outer peel is called the “flavedo”, and it is covered with tiny glands. Each gland contains one drop of essential oil. To extract the organic oil, the glands of the peel must be physically broken open. The main volatile oils in lemon peels are limonene, alpha-terpinene, alpha-pinene, and the main polyphenols in lemon peels are eriocitrin, hesperidin, narirutin, and diosmin.
Expression, or Cold Pressing
Expression refers to the process of slowly breaking down lemon peel under mechanical pressure to release the oils from the glands of the peel. This is process uses Ecuelle a piquer, or an apparatus designed to extract oils from fruit rinds. It began in France as a bowl lined with needles to prick the fruit’s peel, and a funnel to collect the released oils. It has been modernized to accommodate commercial practices, but uses the same principles of poking and agitating the rind.
Cold-pressed means that the oil was expressed at a low temperature. The low temperature preserves the volatile oil, which provides the rich scent of the plant. The oil that is produced will range in color from a deep emerald green to yellow, depending on the how mature the plant was and which variety of lemon was used. If the oil is clear, heat was most likely used in processing, although a cloudy appearance is probably the result of bacteria or wax that has precipitated since processing.
Distillation extraction means exposing a plant to water or steam to break down the plant material and release the essential oil. The oils are cooled and condensed for collection. Distillation is used for lemon peel extraction, although the resulting oil lacks the rich color and odor of fresh lemon peels. This more mild scent may be the motivation for steam distillation, but it has two other advantages.
Steam distilled lemon peel oil will not contain the waxy residue that a cold-pressed oil would contain. This makes them less likely to clog oil diffusers, stain fabric and, as they are less biologically active, extends the shelf life.
The other result of steam distillation is to create an oil that is “psoralen free”, or does not contain the furocoumarins. Furocoumarins have been found to be photocarcinogenic. When these compounds are exposed to light, they can cause mutations in cells that lead to cancer. This correlation between the use of lemon peel extracts containing furocoumarins and skin cancer was first explored in lemon oil as a topical application, such as lotions, in animal studies.
The way this photocarcinogenesis happens is not straightforward, making it hard to know whether all use of lemon oil is a risk factor for developing skin cancer. More recent human studies have found an increase in the incidence of melanoma, basal cell carcinoma and squamous cell carcinoma in people who eat more citrus fruit, although these studies were focusing on furocoumarins from oranges and grapefruit, not specifically lemons. More studies are needed to understand this phenomenon, but it does create value for “psoralen free” lemon peel extracts.
Medicinal Uses for Lemon Oil
Uses in Ayurvedic Medicine
The lemon is considered to be the most valuable of all fruits for preserving health. It used widely in Ayurvedic Medicine, the traditional medicine system of India. It is revered for its cleansing properties. When following an Ayurvedic lifestyle, the recommendation is to begin the day with a glass of lemon water. This is believed to stimulate digestion and purify the body. Lemon is also used to stimulate the nervous system and immune system. Its antimicrobial properties are used to fight viruses, infectious disease, ear infections and cellulitis. Lemon oil topically manages oily skin.
Uses in Chinese Medicine
Lemon is considered a cooling food in Traditional Chinese Medicine, harmonizing the stomach and supporting digestion. Although lemon is strongly acidic as a fruit, it is considered alkalinizing to the body, which is extremely valuable to a society that eats a meat rich diet. Lemon is believed to replenish fluids, including depleted body fluids and unquenched thirst. As in Ayurvedic medicine, it is considered cleansing to the liver, kidneys, blood, mouth and urinary tract.
Hesperidin, a bioflavonoid found in the oil of the lemon peel, has been found to help improve the cognitive deficits that happen in Alzheimer’s Disease. Specifically, aluminum chloride causes oxidative stress in the brain, affecting memory and learning. Hesperidin, when given to animals at the same time as aluminum chloride, prevented the cognitive deficits from happening. Lemon peel essential oils used in a regimen of aromatherapy were shown to be beneficial for improving cognitive function in Alzheimer’s Disease in humans as well.
Stress and anxiety
Lemon essential oils helped lower the stress hormone cortisol in a trial done with rats. Smelling lemon essential oils can raise the heart rate and improve mental and physical performance on tests. Lemon scent improves the overall sense of well-being. People exposed to the scent of lemon reported fewer physical symptoms than they did when smelling something unpleasant. People who smelled lemon essential oils saw a bigger improvement in their mood than people who were exposed to the scent of lavender, which was neutral in its effect.
A trial of 84 premenopausal women assigned to either make no changes, use very low calorie diet with a placebo drink or a very low calorie diet supplemented with lemon juice for 7 days showed promising results for the benefits of lemon juice. In addition to weight loss, which occurred in the lemon and placebo groups, the lemon group saw a reduction in inflammation markers and no loss of important blood markers hemoglobin or hematocrit.
An even stronger effect may be seen when using the polyphenols found in the peel. A study in obese mice on the ability of these polyphenols to break down adipose showed that weight gain was moderated when the mice took hesperidin from lemon peels at the same time as the fatty food. More clinical trials are needed to see if this effect is true for humans as well.
Cancer Prevention and Treatment
Anti-oxidants have long been recognized for their effect on cancer, but promising research is being done into the effect of specific components of the lemon peel. One of the flavonoids in lemon, eriocitrin, has been showed to cause apoptosis, or cell death, in acute myelomonocytic leukemia cells. Limonene is being explored for its effect on breast cancer. It has been shown that this abundant component concentrates well in breast tissue and may play a role in slowing the progression of breast tumors. As complementary care, when given in conjunction with chemotherapy, polyphenols from lemon extracts protected organs from the toxic effects of the chemotherapy.
Oil extracted from the peel of lemons contains several compounds, including 8-geranyloxypsolaren, 5-geranyloxypsolaren and 5-geranyloxy-7-methoxycoumarin that are anti-microbial. These compounds, which are abundant in lemon peel essential oil, kill bacteria such as streptococcus mutans, which cause cavities and periodontitis.
The anti-microbial action and positive impact on mood lend to the popularity of lemon in cleaning products. Lemon is astringing, which means that it tightens tissue. This helps reduce the pain of a swollen throat when lemon is drunk in warm water.
Questions about Lemon Oil
What should I look for in a lemon oil?
Cold pressed lemon essential oils may be bright green to yellow, and should smell strongly like lemons. If they have been distilled they will be clear and may be thinner, as all waxes and residues will have been removed in processing.
Is it safe to use lemon oil on kids?
Do not use lemon oil on the skin of kids if they will be in the sun. It can raise their risk for sunburn or skin cancer. Although other members of the citrus family are common allergens, lemon usually is not, but always watch for irritation when using essential oils on the skin. Allergies can develop over time. Never give a child any essential oil internally. A drop of essential oil diluted in a carrier oil applied to the feet is sufficient to get the benefits for a child.
Can I cook with lemon oil?
Absolutely! Lemon extract is a popular ingredient in baking recipes, and the nutrient rich peel is frequently grated into a zest in cooking. Lemon oil is popular in salad dressing, and can be made at home for optimal freshness. The medicinal properties and scent of the lemon will break down with heat.
How long is the shelf life of lemon oil?
Lemon oil has a short shelf life. It should be stored a dark bottle, in a cool dark place since light and heat will oxidize it, but even under those conditions, it only lasts about 8-10 months. Watch for clouding or an unpleasant smell as signs it has spoiled.
Can I use it on my skin?
Lemon oil is very drying, so it not recommended for use on eczema or other dry skin conditions. Because of this, it is great for treating oily skin, but remember that lemon oil on the skin in the sun is photosensitizing, possibly increasing your risk of a sunburn, and photocarcinogenic, potentially increasing the risk of skin cancer. This will not occur if a soap scented with lemon oils is used, as the soap breaks down the oil and does not leave the furocoumarins on the skin. Use caution with cold pressed lemon oils in products used on sun-exposed skin.
Caution and Considerations
Use caution with lemon oil on the skin. It is photosensitizing and can increase the risk of a sunburn or increase the risk of skin cancer.
While lemon juice is safe to drink, never take essential oils internally. Small doses in a carrier oil on the skin or in cooking is a great way to experience the benefit of nutrient rich lemon peel.
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By Dr. Keri Layton, Naturopathic Medicine