Is There an Environmental Cause of Type 2 Diabetes in the Fongo-Tongo District Population (West Region of Cameroon)?

Worldwide, diabetes is an unremitting disease characterized by amplify in blood glucose, called hyperglycemia (≥200mg/dl or ≥11.1mmol/l in a random blood draw), due to insufficient secretion of insulin by the pancreas or the body’s inability to use insulin called insulin resistance. Persistent, uninhibited high blood glucose will damage organs and parts of the human body. Diabetes is a silent killer or a terrifying disease due to its numerous complications including blindness, kidney failure, heart disease, stroke and lower limb amputation [1]. Is there a link between this disease and firewood smoke?

The cold of the equatorial climate of the western highlands with “mountain facies in Fongo-Tongo District” requires special heating conditions. These include firewood in homes on hearths or rarely in chimneys. Seven months of the year are rainy, notably August, September and October during which the elderly are condemned to stay by the fire all day long. Smoke from burning wood is made up of a complex mixture of gases, toxic air pollutants, and fine particles. The problem is that these microscopic particles in the case of traditional kitchens without chimneys can eventually enter the eyes and the respiratory system. Therefore, they can cause various health problems, such as eye, lung or heart diseases, with harmful effects, especially for people with fragile health [2]. What will be the impacts of smoke on the health of the elderly population most affected? This study therefore aims to establish the link between firewood smoke and rising diabetes among elderly people in Fongo- Tongo. Indeed, Eucalyptus species are abundantly cultivated as a source of timber, carpentry, and cabinetmaking and especially highly used domestic energy. In addition, do Eucalyptus species, abundant in the West region of Cameroon, be an indirect cause of diabetes type 2 and/or play an important role in the treatment of diabetes and hypertension?

To achieve these objectives, we query search engines such as Google, Google scholar, Pubmed, Crossred, through the search keys which are for the most times, titles of different paragraphs of results and discussion of this work. We collect and identify three species of Eucalyptus from sixty samples which were collected in sixty eucalyptus farms.

Of the 47 hypertensive patient’s ages between 76 and 90 years recorded at the Fongo-Tongo District Hospital, 31 developed type 2 diabetes, i.e. 66 % (Head of hospital’s personal communication).

Health impacts of smoke

Breathed in, the fine smoke particles lead to inflammation of the upper respiratory tract which promotes asthma or chronic bronchitis. They manage to pass into the blood, which can cause cardiovascular pathologies and increase the risk of heart attack or stroke. Fine particles can even reach the placenta and have repercussions on the newborn.” These are long-term effects. “Exposure must be repeated and over several years for there to be the appearance of established pulmonary and cardiovascular diseases or cancers. It must have been exposed for at least five to ten years [3].

Cardiovascular or cardio-neurovascular diseases include pathologies that affect the heart and all of the blood vessels, which includes: coronary heart disease (affecting the blood vessels that supply the heart muscle) cerebrovascular diseases (affecting the blood vessels that supply the brain). The seven main cardiovascular diseases are: Myocardial Infarction (MI), Cerebrovascular Accident (CVA), Arteriosclerosis, Angina pectoris, Heart failure, Cardiac arrhythmia and Arterial hypertension. Arterial hypertension is an increase in blood pressure in the arteries; it can be the cause of cardiovascular, cerebrovascular, or even neurodegenerative complications, favorable to diabetes [4]. The resurgence of these two diseases in Fongo-Tongo District makes us think of firewood smoke as their indirect cause.

Hypertension and firewood smoke link

We speak of arterial hypertension when at rest the systolic pressure is higher than 140mmHg and/or when the diastolic pressure is higher than 90mmHg. Air pollution is one of the environmental factors known to play a role in high blood pressure. This cause was demonstrated by the work of a team from Inserm and Sorbonne University, supported by international collaborators and focused on a study of the impact in daily life of a mixture of 5 air pollutants on the blood pressure. Two hundred and twentyone (221) participants were involved in this study, carried out in MobiliSense area, located in Greater Paris territory. In two models, one taking into account the variations in the concentrations of pollutants in the ambient air, the other the variations in the inhaled quantities of these pollutants, the researchers were able to observe an association with acute and repeated increases in blood pressure. This work opens the way to a better understanding of the link between air pollution and hypertension which is a potential risk factor for diabetes [4]. Although the direct link of firewood smoke with diabetes is not yet clarified, as in the case of high blood pressure. Meanwhile, high blood pressure usually provokes diabetes type 2.

Link between hypertension and diabetes

Arterial hypertension is associated with type 2 diabetes in 80% of cases; it contributes to the high risk of cardiovascular disease associated with type 2 diabetes. In general, high blood pressure and diabetes share common causes, linked to the increase in obesity and physical inactivity. These two diseases also interact with each other: a person with hypertension has a greater risk of developing type 2 diabetes [4]. According to John Randolph Petrie et al. [4], hypertensive patients frequently suffering from insulin resistance, present an amplified risk of developing diabetes compared to people with normal blood pressure. This might be due to the following bodily processes common to both illnesses: oxidative stress, obesity, inflammation, activation of the immune system and thickening of the blood vessels. Subsequently hypertension cannot cause diabetes directly; it could boost the risk of a hypertensive patient to develop type 2 diabetes [4]. It was demonstrated that hyperinsulinemia is the cause not only of impaired glucose tolerance, obesity and hypertension, but also of elevated uric acid serum, of an elevation of serum triglycerides as well as of an increase in Na+ in erythrocytes (red blood cells), decrease in red blood cell K+ and increase in plasma K+. All these disorders are risk factor of arterial hypertension and diabetes [5] Are there less polluting woods to use with less risk? Or what woods to avoid reducing the frequency of high blood pressure and therefore diabetes in Fongo- Tongo District?

The combustion of wood emits little carbon dioxide (CO2), the main greenhouse gas 11 times less than fuel oil, 5 times less than gas and 4 times less than electricity [6]. Wood heating is often referred to when we talk about fine particles. At the origin of the emission of 27% of them, its combustion is however less polluting than fossil fuels [7]. Is the eucalyptus, main source of domestic energy in Fongo-Tongo District, good firewood? Due to the high density, well-dried Eucalyptus wood burns very sustainably. In addition, Eucalyptus gives off wonderful, smokeless warmth and has a great perfume [8]. The blocks are extremely hard, so they continue to burn well and are durable. Eucalyptus may be therefore a good source of heating in Fongo-Tongo District [9].

Therapeutic benefits of Eucalyptus species recorded in Fongo-Tongo District

Eucalyptus essential oil is more than 60% citronellal, rich in aldehydes that limit high blood pressure. The wrinkled leaves of the common eucalyptus are used to ward off certain insects or to deodorize. Eucalyptus globulus Labill is traditionally known to reduce intestinal glucose absorption and post-meal blood glucose levels. It is the leaves that help increase insulin secretion. The concentrated dry extract of Eucalyptus globulus Labill, when it is obtained by aqueous extraction of the leaves, is devoid of the characteristic components of the essential oil. The leaves contains phenolic acids, tannins and flavonoids, characteristics of its leaves. Studies show that the leaves of Eucalyptus globulus Labill in the form of an extract have anti-inflammatory, antibacterial and antiviral actions, particularly in the respiratory tract. Some studies have also revealed that Eucalyptus globulus Labill leaves have an antidiabetic action, since they would help reduce hyperglycemia [9]. Eucalyptus Radiata essential oil is renowned for its effectiveness on the treatment of colds, coughs, bronchitis, sinusitis, mainly composed of 1,8-cineole, or eucalyptol, this molecule gives the essential oil a powerful expectorant and mucolytic activity. Antiviral and immunomodulating, it will help relieve certain wet season ailments. The essential oil extracted from the leaves of Eucalyptus globulus has in fact become a reference for naturally treatment of respiratory conditions (bronchitis, flu, laryngitis, pharyngitis, rhinitis, coughs, etc.). It is also known to relieve rheumatic pain and appreciated when diffused to purify indoor air. Diluted in massage oil, Eucalyptus globulus essential oil can be used topically to relieve rheumatic pain [10]. Eucalyptus citriodora essential oil has antiseptic, antibacterial, antiviral and antifungal properties. In cosmetics, it is appropriate for the treatment of acne, scaly skin and wounds. Repellent for insects, it also treats coughs and phlegm. It can also relieve symptoms of respiratory illnesses. It improves concentration and has a harmonizing action. It helps in cases of weariness and promotes harmony and serenity [11].

Ethnopharmacological preparation

We offer the following method of preparation that we have experienced. The pulverized Eucalyptus leaves are infused at the rate of a handful (15g) in a liter of water, for 10 minutes. Drink 250ml of infusion, 3 times a day while controlling blood sugar. The pharmacopoeias confirm this use by reporting uses of hot decoctions of eucalyptus leaves in tea form as oral hypoglycemic [9].

Primary contraindication of this preparation

The main xenobiotics foreign to life are:
a. alcohol,
b. synthetic chemical compounds such as medicines and drugs, pesticides, construction materials, and carcinogenic substances contained in food, which are foreign to living organisms and ecosystems.
c. food additives, including mainly colorings, preservatives, antioxidants, emulsifiers, gelling agents, thickeners, flavor enhancers, and sweeteners.
d. Cosmetics absorbed through the skin, which are beauty products containing very small molecules, such as vitamin C and retinol (vitamin A),
e. a very large number of atmospheric substances, such as nitrogen (78%) and oxygen (21%), and some much less abundant gases such as carbon dioxide (0.038%) and rare gases such as argon.

The release of these xenobiotics and pollutants from eucalyptus leaves could inactivate Sirtuin 1, thereby inducing insulin resistance and chronic diseases. Furthermore, the ethnopharmacological means by which herbal medicines are prepared and administered not only result in a reduced effect in patients, but also in limited drug efficacy due to bioavailability issues, side effects, and unacceptable organoleptic properties. Nanotechnology-based approaches can be used for their delivery to minimize these side effects, bioavailability, and associated organoleptic problems. This would increase the popularity of eucalyptus use against type 2 diabetes. It may be necessary to measure plasma Sirtuin 1 levels in people in the Fongo-Tongo district based on exposure to eucalyptus leaves [11-14].

Analysis of pre-existing uses of Eucalyptus species

Is the oral intake of the infusion of Eucalyptus species beneficial and without risk of toxicity for patients? The answer to this question requires the analysis of pre-existing uses of Eucalyptus species preparations.

Internal therapeutic uses:

a) Infusion: Count 1 level teaspoon, or 1.8 grams of dried leaves, for a cup of 150ml of boiling water. Leave infused for 10 to 15 minutes then filter. Drink 1 to 3 cups between meals. Mother tincture: Take 30 drops in a glass of water, 3 to 4 times a day.
b) Syrup: Count 20 to 30 grams of eucalyptus leaves for 300 ml of boiling water. Leave to infuse for 15 minutes before filtering. Add 300 grams of cane sugar and cook over low heat until the consistency of syrup. Put the preparation in a bottle and keep cool. Drink 2 to 4 tablespoons a day (adult dose) [12].

Eucalyptus trees contain a wide range of phytochemicals demonstrating a range of pharmacological effects, including hypoglycemic action. Volatile and non-volatile constituents of eucalyptus include terpenes and tri-terpenoids, flavonoids, flavanols, gallotannins, quercetin, euglobals, procyanidins, macrocarpals. The presence of these molecules, some of which have hypoglycemic potential, shows that there is enough promise to use eucalyptus or its bioactive phytomolecules as an important therapeutic target against type 2 diabetes [13].

Toxicity and precautions for use

However, eucalyptus is toxic to humans and animals in general. It contains cyanogenic glycosides which can release hydrocyanic acid which works by blocking cellular respiration [12,13].
a) Leaves: Eucalyptus leaf is contraindicated during pregnancy and lactation, in case of inflammation of the bile ducts, gastrointestinal or renal inflammation, and serious liver disease. It is not recommended for children under 3 years old and in case of treatment with iodine substances. Watchfulness is advised in case of antidiabetic treatment because the hypoglycemic effects of eucalyptus can be added to those of drugs. Also consumed in large doses, it can be toxic. Do not exceed the recommended dosage [9,12].
b) Essential oil: Eucalyptus essential oil is not recommended for children under 7 years old. Although, Eucalyptus radiata A.Cunn. ex-DC essential oil is suitable for children. It is contraindicated in case of asthma because it has a drying effect on the mucous membranes. It should not be applied to the face, especially near the nostrils. Prefer external use because 0.4ml of this essential oil is a toxic dose for the body. Ingestion of 10ml of Eucalyptus globulus Labill essential oil can be fatal. Never exceed the indicated doses. Eucalyptus Radiata A.Cunn. ex-DC and E. citriodora Hook essential oils are not recommended during the first 3 months of pregnancy [14-16]. Very flexible in use, unlike certain other Eucalyptus essential oils, Eucalyptus Radiata essential oil is relatively well tolerated by everyone, except people with asthma and epilepsy. Pregnant women under 3 months and infants less than 3 months must avoid use it. All routes of administration are permitted, however it is preferable to dilute it in diffusion, because it is sensitizing to the respiratory tract, and during cutaneous application because of its irritating nature for the skin [10].

Mitigation measures for the impact of wood smoke

The condition of the wood you burn and how you store it are also important:
i. The wood must breathe. To this end, the wood must be stacked in such a way as to allow air to circulate freely in the hearth.
ii. Use small logs which are a better source of heat.
iii. Use well-seasoned wood.
iv. Do not burn prohibited items such as household waste or cardboard, fresh, damp, rotten, infected or moldy wood, painted or chemically treated wood, driftwood, plywood, particle board or wood that contains glue, both outside and inside
v. To avoid this situation, the construction of spacious, wellventilated and high kitchens with keep up chimneys and large openings can reduce the problem.
vi. It is also urgent to take measures, such as expanding early detection and fighting against diabetes services in urban and rural areas.

At the end of this study, we find that air pollutants from wood smoke like PM can provoke high blood pressure, rick factor of diabetes type 2. Consequently, wood smoke has environmental pollutants which are indirect and non-metabolic causes of diabetes, after a long-term inhalation of firewood smoke, in traditional kitchens. Though this firewood smoke may be indirectly responsible of diabetes type 2, because arterial hypertension is a natural risk factor of type 2 diabetes. Our study identified an environmental cause of type 2 diabetes, confirmed by previous studies, in rural areas [17-19].

Three Eucalyptus species (Eucalyptus globulus, Eucalyptus radiata end Eucalyptus citriodora) recorded are widely used in Fongo-Tongo District. They give off wonderful smokeless warmth and have a great perfume, especially Eucalyptus globulus. Therefore, they are best firewood that can help to reduce the frequency of hypertension in elderly and consequently that of diabetes type 2. However, the observation of the measures described above remains essential to mitigate the impacts of smoke on human health and the environment. These measures can also reduce the risks of diabetes linked to arterial hypertension caused by firewood smoke. Keeping in mind the hypoglycemic potential of eucalyptus, efforts are needed to develop therapeutics with defined dosages with extracts or isolated bioactive compounds of eucalyptus. Advances in nanotechnology can be exploited for their release to alleviate the side effects, bioavailability and organoleptic problems associated with them. The present work may stimulate the increase in popularity of the therapeutic use of eucalyptus leaves for type 2 diabetes.

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