Food therapy - Avocado

By Kyle J. Norton

Avocado is a commercially valuable fruit cultivated in tropical climates throughout the world. it is a green-skinned, pear-shaped fruit that ripens after harvesting and native to the Caribbean, Mexico, South America and Central America, belonging to the flowering plant family Lauraceae.
Nutrients
1. Vitamin K
2. Dietary fiber
3. Vitamin B6
4. Vitamin C
5. Folate
6. Copper
7. Potassium
8. Amino acid
9. Others
a) Vitamin A
b) Vitamin B1, B2, B3, B12
c) Vitamin D
d) Vitamin E
e) Carotenoid
f) Pantothenic acid
g) Calcium
h) Chromium
Chemical constituents
The fruit contains campesterol, high amounts of β-sitosterol (average 76.4 mg/100 g); fatty acids (approximately 60% monounsaturated, 20% saturated, and 20% unsaturated); high amounts of glutathione (27.7 mg/100 g); approximately 2% protein; 6–9% carbohydrates and sugars (glucose, fructose, d-mannoheptulose, a taloheptulose, and an alloheptulose); two bitter substances (1-acetoxy-2,4-dihydroxyheptadeca-16-ene and 1,2,4-trihydroxyheptadeca-16-ene); carnitine; proanthocyanidins; persenones A and B(a).

1. Avocado and leukemia
Hass avocados, the most common commercial avocado cultivars in the world, not only support the  cardiovascular health also process the properties in maintaining healthy weight  and healthy aging(1).
Endocarp, seed, whole seed, and leaf (0.1 mg/mL) extracts showed to inhibit leukemic cell profileration through an oxidative stress mechanism, according to the University of Antioquia(2)

References
(a) Leung's Encyclopedia of Natural Ingredients:Chemical Composition of Avocado
(1) Hass avocado composition and potential health effects by Dreher ML¹, Davenport AJ.(PubMed)
(2) Pro-apoptotic effect of Persea americana var. Hass (avocado) on Jurkat lymphoblastic leukemia cells by Bonilla-Porras AR¹, Salazar-Ospina A, Jimenez-Del-Rio M, Pereañez-Jimenez A, Velez-Pardo C.(PubMed)
(3)

2. Avocado and Cholesterol
Cholesterol is needed for our body to build cell walls, make hormones and vitamin D, and create bile salts that help you digest fat. However too much of it can be dangerous because cholesterol cannot dissolve in your blood. The special particle called lipoprotein moves this waxy, soft substance from place to place.
Avocado may be one of best fruit used to reduce the accumulation of bad cholesterol in the blood, as it process body fat lowering capacity. The fruit was also found to reduced risk of metabolic syndrome(1), including obesity(2) and cardiovascular diseases(3) According to Dr. Monika P, and Dr. Geetha A., hydro-alcoholic fruit extract of P. americana (HAEPA) in a  a period of 14 weeks rat study, showed a significantly decreased body mass index (BMI), total fat pad mass and adiposity index. Levels of reduced glutathione, adiponectin, mRNA expression of adiponectin were significant lower in rat in rats fed a high-fat diet (HFD)(4). The study of the level of expression of adiponectin and PPAR-γ in rats, Persea americana (avocado) fruit extract enhanced the HAEPA exhibition of hypolipidemic activity probably by increasing the mRNA, which is RNA messenger expression of adiponectin, a protein with function in regulating glucose levels as well as fatty acid breakdown. and PPAR-γ, a protein with function in regulation of cellular metabolism (carbohydrate, lipid, protein), and tumorigenesis, which reduce the risk of hyperlipidemia and obesity(5). In support of the view of above, researchers at the Potchefstroom University for Christian Higher Education, suggested that consumption of 200 g/d of avocado within an energy-restricted diet does not compromise weight loss when substituted for 30 g of mixed dietary fat. Serum lipid concentrations, plasma fibrinogen, arterial compliance, and systolic and diastolic blood pressures were not affected by weight loss or avocado intake(6).

References
(1) Avocado consumption is associated with better diet quality and nutrient intake, and lower metabolic syndrome risk in US adults: results from the National Health and Nutrition Examination Survey (NHANES) 2001-2008 by Fulgoni VL 3rd¹, Dreher M, Davenport AJ.(PubMed)
(2) Effect of Persea americana (avocado) fruit extract on the level of expression of adiponectin and PPAR-γ in rats subjected to experimental hyperlipidemia and obesity by Monika P, Geetha A.(PubMed)
(3) Avocado oil supplementation modifies cardiovascular risk profile markers in a rat model of sucrose-induced metabolic changes by Carvajal-Zarrabal O¹, Nolasco-Hipolito C², Aguilar-Uscanga MG³, Melo-Santiesteban G⁴, Hayward-Jones PM¹, Barradas-Dermitz DM⁵.(PubMed)
(4) Effect of Persea americana (avocado) fruit extract on the level of expression of adiponectin and PPAR-γ in rats subjected to experimental hyperlipidemia and obesity by Monika P, Geetha A.(PubMed)
(5) Effect of Persea americana (avocado) fruit extract on the level of expression of adiponectin and PPAR-γ in rats subjected to experimental hyperlipidemia and obesity by Monika P, Geetha A.(PubMed)
(6) Substitution of high monounsaturated fatty acid avocado for mixed dietary fats during an energy-restricted diet: effects on weight loss, serum lipids, fibrinogen, and vascular function by Pieterse Z¹, Jerling JC, Oosthuizen W, Kruger HS, Hanekom SM, Smuts CM, Schutte AE.(PubMed)

3. Avocado and Diabetes
Diabetes is defined as a condition caused by insufficient insulin entering the bloodstream to regulate the glucose. It is either caused by cells in pancreas dying off or receptor sites clogged up by fat and cholesterol. In some cases, diabetes is also caused by allergic reactions of cells in the immune system.

Extracts of Persea americana Mill (Lauraceae) ("Avocado") has been used in folk medicine to treat hypertension and lower blood glucose, but the underlined  mechanism is unknown. According to University of KwaZulu-Natal, in STZ-induced diabetic rats, the avocado extract may be used in diabetic management through its effectiveness in increased hepatic glycogen concentrations, decreased urine flow and electrolyte excretion rates, whilst subchronic treatment reduced plasma creatinine and urea concentrations(1). Other study suggested that consuming monounsaturated fatty acids in avocado in the diet of patients with non-insulin-dependent diabetes mellitus improves the lipid profile favorably, maintains an adequate glycemic control, and offers a good management alternative(2) and high-monounsaturated fat diet metabolited better in some aspects than the currently recommended diet for non-insulin-dependent diabetes mellitus (NIDDM)(3).


References
(1) Effects of Persea americana Mill (Lauraceae) ["Avocado"] ethanolic leaf extract on blood glucose and kidney function in streptozotocin-induced diabetic rats and on kidney cell lines of the proximal (LLCPK1) and distal tubules (MDBK), by Gondwe M¹, Kamadyaapa DR, Tufts MA, Chuturgoon AA, Ojewole JA, Musabayane CT.(PubMed)
(2) Effect of a high-monounsaturated fat diet enriched with avocado in NIDDM patients by Lerman-Garber I¹, Ichazo-Cerro S, Zamora-González J, Cardoso-Saldaña G, Posadas-Romero C.(PubMed)
(3) The high-monounsaturated fat diet as a practical alternative for NIDDM by Campbell LV¹, Marmot PE, Dyer JA, Borkman M, Storlien LH.(PubMed)

4. Avocado and Cardiovascular disease
Heart diseases are caused by high blood pressure that contributes to hardening of the arteries. High levels of bad cholesterol (LDL) building up in the arteries as a result of uncontrolled diet with high levels of saturated fat and trans fat.
In animal study,  Persea americana Mill (Lauraceae) aqueous leaf extract (PAE) showed a significant effect in reduced risk and treatment of heart diseases through its hypotensive (antihypertensive) effects(1). According to Nutrition Science Solutions LLC, consumption of one-half an avocado (68 g), not only provided many nutrients for body needed, but also supported cardiovascular health(2).
The National Health and Nutrition Examination Survey (NHANES) 2001-2008, suggested that avocado consumption is associated with improved overall diet quality, nutrient intake, and reduced risk of metabolic syndrome(3), including cardiovascular disease.

References
(1) Cardiovascular effects of Persea americana Mill (Lauraceae) (avocado) aqueous leaf extract in experimental animals by Ojewole JA¹, Kamadyaapa DR, Gondwe MM, Moodley K, Musabayane CT.(PubMed)
(2) Hass avocado composition and potential health effects by Dreher ML¹, Davenport AJ.(PubMed)
(3) Avocado consumption is associated with better diet quality and nutrient intake, and lower metabolic syndrome risk in US adults: results from the National Health and Nutrition Examination Survey (NHANES) 2001-2008 by Fulgoni VL 3rd¹, Dreher M, Davenport AJ.(PubMed)

5. Avocado and Anti inflammatory effect
The immune system is the set of cells and their activity against antigens or infectious agents that comprises of the body's defense system against diseases. The immune system does a great job of keeping people healthy and preventing infections. Beside foods and nutritional supplements, herbs also play a important role in helping the immune system defend against viruses and bacteria attacks.
In UV-induced damage in skin cells, the unique lipid molecules, polyhydroxylated fatty alcohols (PFA), extracted from avocado, showed to reduce UVB-induced damage and inflammation in skin. Application of the extract  prior to their exposure to UVB enhanced a protective effect, increased cell viability, decreased the secretion of IL-6, a pro-inflammatory cytokine and an anti-inflammatory myokine. and PGE(2) in mediated the inflammation process , and DNA repair(1).
Avocado soybean unsaponifiables (ASU)supplement, when applied alone, exhibited pain-reducing and anti-inflammatory effects, through suppressing TNF-alpha, a pleiotropic inflammatory cytokine, IL-1beta which plays a central role in the regulation of immune and inflammatory responses, COX-2 which  involved in the conversion of arachidonic acid to prostaglandin H2, iNOS gene expression which involved in immune response, and prostaglandin E2 and nitric oxide production in articular chondrocytes and monocyte/macrophages(3). When used combination with epigallocatechin gallate, in the study by Nutramax Laboratories, Avocado soybean unsaponifiables (ASU)supplement demonstrated a significantly anti-inflammatory activity and may offer an attractive supplement or alternative to non-steroidal anti-inflammatory drugs (NSAIDs) in the management of osteoarthritis(2).

References
(1) Polyhydroxylated fatty alcohols derived from avocado suppress inflammatory response and provide non-sunscreen protection against UV-induced damage in skin cells by Rosenblat G¹, Meretski S, Segal J, Tarshis M, Schroeder A, Zanin-Zhorov A, Lion G, Ingber A, Hochberg M.(PubMed)
(2) Inhibition of cyclooxygenase-2 expression and prostaglandin E2 production in chondrocytes by avocado soybean unsaponifiables and epigallocatechin gallate by Heinecke LF¹, Grzanna MW, Au AY, Mochal CA, Rashmir-Raven A, Frondoza CG.(PubMed)
(3) Avocado soybean unsaponifiables (ASU) suppress TNF-alpha, IL-1beta, COX-2, iNOS gene expression, and prostaglandin E2 and nitric oxide production in articular chondrocytes and monocyte/macrophages by Au RY¹, Al-Talib TK, Au AY, Phan PV, Frondoza CG.(PubMed)

6. Avocado and as Antioxidant
Free radicals are atoms, molecules, or ions with unpaired electrons through chemical bonds with other atoms or molecules during a chemical reaction. They may have positive, negative or zero charge. The unpaired electrons cause radicals to be highly chemically reactive in the human body, leading to aging and cancers.
eEthyl acetate, containing 70% acetone, and 70% methanol extracts of the peel, pulp, and seed from two avocado (Persea americana Mill) exerted its antioxidant activity in vitro against microbial pathogens,  including Gram-positive bacteria through inhibition of oxidative stress(1). the Tecnológico de Monterrey-Campus Monterrey suggested that avocado pulp may sever as a novel lipophilic antioxidants in a food matrix due to the presence of acetogenins(2), a class of polyketide natural products found in plants. The University of California in the study of the effect of harvest date on nutritional compounds and antioxidant activity (AOC) in avocado (Persea americana Mill. cv Hass) fruit , suggested that AOC in early harvested fruit after storage for 35 days was much higher than that in late harvested fruit after storage for 21 days(3).

References
(1) Avocado (Persea americana Mill.) phenolics, in vitro antioxidant and antimicrobial activities, and inhibition of lipid and protein oxidation in porcine patties by Rodríguez-Carpena JG¹, Morcuende D, Andrade MJ, Kylli P, Estévez M.(PubMed)
(2) Activity-guided identification of acetogenins as novel lipophilic antioxidants present in avocado pulp (Persea americana) by Rodríguez-Sánchez D¹, Silva-Platas C, Rojo RP, García N, Cisneros-Zevallos L, García-Rivas G, Hernández-Brenes C.(PubMed)
(3) Effect of harvest date on the nutritional quality and antioxidant capacity in 'Hass' avocado during storage by Wang M¹, Zheng Y, Khuong T, Lovatt CJ.(PubMed)

8. Avocado and osteoarthritis
Osteoarthritis is a group of diseases involved progressive denegation of joints, including articular cartilage and subchondral bone.
Avocado/soybean unsaponifiables (ASU) supplement, in the searching for randomised, placebo-controlled, double-blind trials of ASU, suggested that ASU improved the symptoms of OA, with only real long-term trial yielded a largely negative result, according to Dr. Ernst E.(1). The Frederiksberg Hospital in the study of the same, with 664 OA patients with either hip (41.4%) or knee (58.6%) suggested that the 3 months, Avocado/soybean unsaponifiables (ASU) supported better chances of success in patients with knee OA than in those with hip OA(2). Other study also found a significantly effective of the supplement ASU in reduced the progression of joint space loss as compared with placebo in the subgroup of patients with advanced joint space narrowing, but require confirmation in a larger placebo-controlled study in hip OA(3).

References
(1) Avocado-soybean unsaponifiables (ASU) for osteoarthritis - a systematic review by Ernst E.(PubMed)
(2) Symptomatic efficacy of avocado-soybean unsaponifiables (ASU) in osteoarthritis (OA) patients: a meta-analysis of randomized controlled trials by Christensen R¹, Bartels EM, Astrup A, Bliddal H.(PubMed)
(3) Structural effect of avocado/soybean unsaponifiables on joint space loss in osteoarthritis of the hip by Lequesne M¹, Maheu E, Cadet C, Dreiser RL.(PubMed)

9. Avocado and Prostate Cancer
Intake of dietary MUFA from whole fruit of avocado are associated to reduced risk of prostate cancer, The new study at the University of the West Indies suggested(1). In support of the above, the University of California suggested that the anti prostate cancer effect are not as result of a single ingredient such as related carotenoids (zeaxanthin, alpha-carotene, and beta-carotene), lutein but the interaction of all ingredients in the whole fruit conbination with other det-derived phytochemicals through cell cycle arrest and  G(2)/M cell cycle arrest accompanied by an increase in p27 protein in controlling the cell cycle progression at G1 in incubation of PC-3 cells(3). The Purdue University study in the evaluation of the anti cancers effect of avocado also showed  a positive effect of the whole fruit in inhibition of six human tumor cell lines in culture, including human prostate adenocarcinoma (PC-3) cells(4).

References
(a) Leung's Encyclopedia of Natural Ingredients:Chemical Composition of Avocado
(1) Associations of whole-blood fatty acids and dietary intakes with prostate cancer in Jamaica by Jackson MD¹, Walker SP, Simpson-Smith CM, Lindsay CM, Smith G, McFarlane-Anderson N, Bennett FI, Coard KC, Aiken WD, Tulloch T, Paul TJ, Wan RL.(PubMed)
(2) Inhibition of prostate cancer cell growth by an avocado extract: role of lipid-soluble bioactive substances. by Lu QY¹, Arteaga JR, Zhang Q, Huerta S, Go VL, Heber D.(PubMed)
(3) Cytotoxic and insecticidal constituents of the unripe fruit of Persea americana by Oberlies NH¹, Rogers LL, Martin JM, McLaughlin JL.(PubMed)

10. Avocado and Breast cancer
Persin, the toxin chemical compound found in the fruits and leaves of avocado showed to inhibit human breast cancer cell line, in the testing of synthetic analogues of the avocado-produced toxin persin(1). In support to the above, researchers at the Gavan institution, suggested that persin could be given together with commonly used breast cancer drugs like tamoxifen, which seem to act in a different way, but patients would benefit by needing smaller amounts of each type of medicine. Indeed, in the laboratory, persin and tamoxifen look to be a good combination(2). Other member of Persea, Persea declinata (Bl.) Kosterm  from the same genus with avocado, in  the Lauraceae family and widely distributed in Southeast Asia, in the testing against MCF-7 Cells showed that its bark methanolic crude extract (PDM) found to inhibit cell cycle arrest and subsequently induced apoptosis through increased the expression of the proapoptotic molecule, Bax(pro-apoptosis), but decreased the expression of prosurvival proteins, Bcl-2 (pro-apoptotic oranti-apoptotic) and Bcl-xL(pro- and anti-survival protein) in a dose-dependent manner(3).


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References
(a) Leung's Encyclopedia of Natural Ingredients:Chemical Composition of Avocado
(1) Synthesis and in vitro evaluation of analogues of avocado-produced toxin (+)-(R)-persin in human breast cancer cells by Brooke DG¹, Shelley EJ, Roberts CG, Denny WA, Sutherland RL, Butt AJ.(PubMed)
(2) Persin - the avocado toxin that kills breast cancer cells(Gavan Institution)
(3) Persea declinata (Bl.) Kosterm Bark Crude Extract Induces Apoptosis in MCF-7 Cells via G0/G1 Cell Cycle Arrest, Bcl-2/Bax/Bcl-xl Signaling Pathways, and ROS Generation by Narrima P¹, Paydar M¹, Looi CY¹, Wong YL¹, Taha H², Wong WF³, Ali Mohd M¹, Hadi AH(PubMed)

11. Avocado and Skin health
In a in growing rats fed diets containing 10% (w/w) of the tested oils, showed to increased soluble collagen content due to a result of a consequence of the inhibition of lysyl oxidase activity(1). On wound healing in rats, after  the 14th day of treatment with 50% SSFAO or avocado oil containing rich source of oleic acid and essential fatty acids, exhibited a significant increase in percentage wound contraction and reepithelialisation(2). In Exposing skin to ultraviolet (UV) radiation, unique lipid molecules, polyhydroxylated fatty alcohols (PFA), extracted from avocado, reduced significantly UV-induced cellular damage, through increasing cell viability, decreased the secretion of IL-6, a pro-inflammatory cytokine and an anti-inflammatory myokine. and PGE(2) in mediated the inflammation process(3).

References
(1) The effect of various avocado oils on skin collagen metabolism by Werman MJ¹, Mokady S, Nimni ME, Neeman I.(PubMed)
(2) Effect of semisolid formulation of persea americana mill (avocado) oil on wound healing in rats by de Oliveira AP¹, Franco Ede S, Rodrigues Barreto R, Cordeiro DP, de Melo RG, de Aquino CM, E Silva AA, de Medeiros PL, da Silva TG, Góes AJ, Maia MB.(PubMed)
(3) Polyhydroxylated fatty alcohols derived from avocado suppress inflammatory response and provide non-sunscreen protection against UV-induced damage in skin cells by Rosenblat G¹, Meretski S, Segal J, Tarshis M, Schroeder A, Zanin-Zhorov A, Lion G, Ingber A, Hochberg M.(PubMed)


Side effects
1. Skin product of avocado oils may contain latex which can cause skin side effect in certain people with hypersensitivity to latex, leading to symptoms of reddening of the skin, itching, hives, or eczema.
2. Liver damage
Certain types of avocado may cause liver damage as a result of collagen accumulation in the liver
3. Breastfeeding
Some types of Avocado may be unsafe during breastfeeding as it can cause problems of upset stomachs in babies.
4. Drugs
Avocado may decrease the effect of "blood thinning" or anti-inflammatory medications.
5. It may cause symptoms of gastrointestinal irritation, vomiting, diarrhoea, respiratory distress, congestion, fluid accumulation due to toxic fatty acid derivative, Persin.
6. Etc.