Auscultation: A Clinical Perspective

Auscultation and the Stethoscope: A Clinical Perspective

by: lim ju boo alias lin ru wu (林 如 武)

Introduction:

Ancient civilizations started listening to breath sounds for diagnosis appear in the Ebers Papyrus of Ancient Egypt (c. 1500 BCE) and the Hindu Vedas (c. 1400–1200 BCE).  In  ancient Greece (c. 440–360 BCE), Hippocrates practiced "immediate auscultation" by applying his ear directly to the patient's chest. He described sounds such as the "frictional rub" of pleuritis and "succussion splash" (the sound of fluid in the chest when a patient is shaken).

In the late Renaissance to 18th Century William Harvey (1628) provided the first detailed description of heart sounds as "two clacks of a water bellows".  Robert Hooke (17th century) predicted that internal sounds could reveal which "internal parts of bodies" were out of order.  James Douglas (1715) and William Hunter (1757) recorded specific heart murmurs heard even at a distance from the patient

Thus, in ancient times physicians began actively listening to body sounds (auscultation) by merely placing their ears on the body without needing any stethoscope as a diagnostic practice until  the early 19th century when the stethoscope was invented as a more convenient method.  Before the stethoscope, some basic forms of listening (immediate auscultation) involved placing an ear directly to the body, a practice noted as far back as Hippocrates, as I have already mentioned. The pivotal shift occurred in 1816 when French physician René-Théophile-Hyacinthe Laennec invented the first stethoscope in Paris.

He used a rolled tube of paper to listen to a patient's heart and lungs, finding the sounds clearer and the method more effective and discreet than immediate auscultation . This invention allowed physicians to listen to internal sounds with unprecedented clarity, leading to the development of a systematic understanding of the sounds produced by various heart and lung conditions.

 I have personally heard exactly the same sounds produced by the body without needing any stethoscope by merely placing my ears over the hearts of children with congenital heart problems  when their parents brought them to see me when I was having my dinner in a restaurant. Surely you don't expect me to carry a stethoscope to a restaurant, to the shop or to the supermarket or when I needed to attend to a unexpected medical emergency such as in a road accident.  Without any stethoscope,  I merely placed my ears on various regions on the precordium  (regions in the chest wall over the heart), and I could distinctly hear the murmurs and even classified the types and their underlying causes or pathology. I shall describe these pathological sounds later as I write along here.  The stethoscope  merely made it more easier and convenient for physicians.  Thus, the stethoscope was quickly adopted, and by the mid-19th century, listening to body sounds had become a basic  component of the physical examination

Auscultation to most ordinary clinicians view it as one of their most venerable and fundamental clinical skills in medicine despite the fact we now use far more advanced electronic, laboratory,  imaging and even molecular diagnostic techniques to diagnose especially for differential diagnosis and in cases where the diseases produce no sound such as diabetes, inflammation, fever, infection, cancer, a fracture (x-ray is needed), or malaria (thick stained blood film under a microscope is needed), or high blood pressure (except those sounds of Korotkoff heard when measuring blood pressure using a mercurial blood pressure instrument). Not all diseases can be diagnosed using a stethoscope. 

  

Auscultation is the act of listening to internal bodily sounds to evaluate physiological processes and discern potential pathology. Since René Laennec's invention of the stethoscope in 1816, this technique is indispensable in the bedside examination of patients, particularly in the assessment of the respiratory and cardiovascular systems, as well as in the identification of vascular abnormalities such as bruits. Despite the emergence of advanced diagnostic technologies which we now use in major hospitals with technological facilities, auscultation continues to maintain a primary role due to its simple, immediacy, non-invasiveness, and capacity to yield vital diagnostic insights (1,2).

 

Let us now have a look at:  

Auscultation of the Respiratory System  

 

When appraising the thorax, auscultation enables the clinician to evaluate airflow dynamics within the lungs and detect abnormal or adventitious sounds. The primary normal respiratory sound is the vesicular breath sound, which is audible over the majority of lung fields. These sounds are characterized by their soft and low-pitched quality, reminiscent of a gentle rustling. They manifest during active inhalation as air traverses into the bronchi and alveoli, persisting through passive exhalation driven by alveolar elastic recoil. The phases of these sounds can be broadly delineated as the tubular component, succeeded by the alveolar phases during both inspiration and expiration (3).

 

Any deviation from this normative pattern may signify underlying pathology. For instance, bronchial breath sounds, if detected in peripheral lung fields, may indicate consolidation, as seen in pneumonia, while adventitious sounds such as crackles, wheezes, or rhonchi may reflect conditions such as pulmonary fibrosis, asthma, or chronic obstructive pulmonary disease (3,4).

Auscultation of the Cardiovascular System  

Let  us now go into listening to the heart.  Cardiac auscultation entails the act of listening to the heart using a stethoscope to assess valve functionality and identify abnormal blood flow patterns. Both the diaphragm and the bell of the stethoscope are employed: the diaphragm for high-pitched sounds such as the first (S1) and second (S2) heart sounds, and the bell for low-pitched sounds such as the third (S3) and fourth (S4) heart sounds, or certain diastolic murmurs (5).

A systematic approach is imperative. The examination typically commences at the apical impulse and progresses to the lower left sternal border, the right and left upper sternal borders, and ultimately to the axilla when indicated. Various patient positions, including supine, sitting forward, and left lateral decubitus, are often utilized to accentuate specific sounds (6).

The normal heart sounds comprise S1, produced by the closure of the mitral and tricuspid valves, and S2, resulting from the closure of the aortic and pulmonic valves. Physiological splitting of S2 during inspiration is commonplace and generally benign. Abnormal sounds encompass S3, associated with rapid ventricular filling and often suggestive of heart failure, and S4, which arises from atrial contraction against a stiff ventricle, potentially indicating left ventricular hypertrophy or ischemia (7).

Murmurs represent additional sounds generated by turbulent blood flow across valves. They are described by their timing within the cardiac cycle, intensity, pitch, location, and radiation. Systolic murmurs occur between S1 and S2 and may be further classified as midsystolic, holosystolic, or late systolic. Diastolic murmurs transpire between S2 and S1, while continuous murmurs extend across both systole and diastole. Noteworthy examples include the holosystolic murmur of mitral regurgitation radiating to the axilla, the pansystolic murmur of tricuspid regurgitation accentuated during inspiration, the harsh pansystolic murmur of a ventricular septal defect at the left sternal border, and the Austin Flint murmur indicative of severe aortic regurgitation (8,9). Innocent murmurs, such as Still’s murmur in children, may also be encountered and must be differentiated from pathological murmurs.

To standardize assessment, systolic murmurs are classified from I to VI, with grade I being scarcely perceptible and grade VI audible without the stethoscope in contact with the chest. Murmurs graded IV or higher are typically associated with a palpable thrill (5). The early identification of abnormal heart sounds is of paramount clinical importance, as it enables timely intervention, mitigates morbidity, and enhances patient outcomes (7).

 

Let us now go into listening to stenosed blood vessels. Auscultation of Blood Vessels: Bruits

Beyond the examination of the lungs and heart, auscultation is useful for evaluating major blood vessels. A bruit is an aberrant, blowing or whooshing sound discerned over an artery, resulting from turbulent blood flow through a narrowed or partially obstructed vessel. In contrast to heart murmurs, bruits are extracardiac and generally signify vascular pathology.

Common sites for the auscultation of bruits encompass the carotid arteries in the neck, the abdominal aorta, the renal arteries, as well as the iliac and femoral arteries. Aetiological factors include arterial stenosis, often attributable to atherosclerotic plaque, or other obstructive lesions. Clinically, the identification of a carotid bruit holds particular significance, as it may indicate carotid artery disease and herald an elevated risk of stroke (10). Similarly, abdominal or renal bruits can denote aneurysm or renovascular hypertension, conditions necessitating further imaging and prompt intervention.

 

Besides listening to the symptoms the patients tells, looking for signs physically and taking medical history, auscultation and the utilization of the stethoscope is the basic element of clinical examination. Whether assessing vesicular breath sounds, differentiating complex cardiac murmurs, or detecting vascular bruits, auscultation can yield basic interpretation  into the underlying physiology and pathology of the patient. While contemporary imaging and other electronic diagnostic techniques, including genetic and molecular analysis and other highly sophisticated blood, urine and other biological examination that  provide highly advanced enhanced precision these days with the advancement of medicine through research, the art of attentive listening remains the simplest basic for bedside evaluation, early diagnosis, and clinical decision-making. Mastery of this skill not only augments diagnostic accuracy using other more advanced approaches but also sustains the tradition of listening to body sounds since the time of Hippocrates. Engaging in this simple process allows for the exploration of subtle shades that may escape more mechanized assessments.

Moreover, the ability to discern minute variations in sound can unveil a myriad of conditions, from valvular heart diseases to systemic ailments, where the implications of timely recognition can be life-altering. This diagnostic skill transcends routine practice and has now become an art form, one that demands both patience and profound attentiveness. besides listening carefully what the patient tells us about their complaints and medical history we take, which to me is the most important because we can already diagnose with 75 % accuracy without using any stethoscope or using other advanced methods that are available only in tertiary and teaching hospitals.  

As our inroads in medicine evolves through research and studies,  integrating technological advances with traditional methodologies, the role of auscultation should not be relegated to obsolescence. Rather, it should be viewed as an essential complement to innovative diagnostic tools, serving to enrich the clinician’s toolkit. The harmony between advanced imaging and the traditional technique of auscultation ensures a holistic approach to patient care, empowering practitioners with a comprehensive understanding of health dynamics.

We may say, as the complexities of modern medicine continue to expand, the fundamental principles of clinical assessment such as listening carefully to the complaints of the patient, taking their medical history, and conducting simple clinical examinations remain steadfast. The mastery of auscultation, with its capacity to provide immediate feedback and understanding, is the basic asset in the clinician's repertoire. It not only enhances primary diagnoses but also reinforces the humanistic aspects of medical practice, ensuring that care remains not only effective but deeply empathetic. Thus, embracing and refining the art of auscultation as ones of them, this will continue to be paramount as we navigate the intricate interplay between health and healing in the evolving scenario of healthcare.

Let me classify the sounds we can hear in a table form. Sorry for the table congestion as I have no space in this simple article I write as I need to squeeze all of them in. 

 

System	Normal Sounds		Abnormal Sounds	Clinical Significance
Respiratory	Vesicular breath sounds: soft, low-pitched, rustling, heard across most lung fields		Bronchial breath sounds in periphery; Adventitious sounds (crackles, wheezes, rhonchi)	Consolidation (pneumonia), asthma, COPD, fibrosis
Cardiac – Heart Sounds	S1: closure of mitral & tricuspid valves; S2: closure of aortic & pulmonic valves (physiological splitting in inspiration)		S3: rapid ventricular filling (HF); S4: atrial contraction against stiff ventricle (LVH, ischemia)	Heart failure, hypertrophy, ischemic heart disease
Cardiac – Murmurs	None		Systolic, diastolic, or continuous murmurs, described by timing, pitch, intensity, radiation	Valvular disease (e.g., MR, TR, VSD, AR, AS)
Cardiac – Murmur Examples	Innocent murmurs (e.g., Still’s murmur in children)		Austin Flint (severe AR); Graham Steell (pulmonary regurgitation); Holosystolic MR/TR murmurs	Differentiates benign vs. pathological murmurs
Vascular	No bruit		Bruit: blowing/“whooshing” sound over artery	Carotid bruit (stroke risk), renal bruit (renovascular HTN), abdominal bruit (aneurysm)

Clinical Pathway of Auscultation: 

 

Step 1: Preparation

Ensure a quiet environment.

Patient positioned appropriately (supine, sitting, left lateral, etc.).

Use diaphragm and bell of stethoscope correctly.

 

Step 2: Systematic Listening

Respiratory system: Listen over multiple lung fields (anterior, posterior, lateral).

Cardiovascular system: Listen systematically over the four valve areas (aortic, pulmonic, tricuspid, mitral) and axilla if needed.
Vascular system: Listen over carotids, abdominal aorta, renal, femoral, and iliac arteries when indicated.

 

Step 3: Identify Normal vs. Abnormal

Respiratory: Vesicular vs. bronchial/adventitious sounds.

Cardiac: S1, S2 normal; presence of S3, S4, murmurs.
Vascular: Presence or absence of bruits.

 

Step 4: Characterization of Abnormal Sounds

Respiratory: Type of adventitious sound (crackles, wheezes, rhonchi).

Cardiac murmurs: Timing (systolic, diastolic, continuous), pitch, intensity (I–VI), location, radiation, quality.
Bruits: Site, intensity, duration.

Step 5: Correlate with Clinical Context
Match auscultatory findings with symptoms (dyspnea, chest pain, syncope).
Integrate with physical signs (cyanosis, edema, pulse quality, BP changes).

 

Step 6: Clinical Decision

Normal findings → reassurance and routine monitoring.

Abnormal but benign (e.g., Still’s murmur) → observation.

 

Pathological findings → further investigations:

 

Respiratory: Chest X-ray, CT, spirometry.
Cardiac: Echocardiography, ECG.
Vascular: Doppler ultrasound, CT angiography.

Step 7: Management and Follow-up

Use auscultatory findings as early diagnostic evidence.

Guide medical/surgical treatment decisions.
Monitor progression or resolution during follow-up.

 

A Medical Psalm: The Shepherd’s Auscultation

 

“The Lord is my Shepherd; I shall not want. He makes me lie down in green pastures; He leads me beside still waters; He restores my soul.” 

(Psalm 23:1–3)

So too, the physician with stethoscope in hand becomes a shepherd of the patient. To auscultate is to pause, to lean in, and to listen, not only to the rhythms of heart and lung, but to the unspoken fears and silent hopes of the one who suffers.

1. The quiet room is the green pasture.

2. The still diaphragm of the stethoscope is the still water.

3. The sounds of the heart and lungs are the voice of the flock, calling for guidance.

When the physician listens with humility, wisdom, and compassion, auscultation becomes more than a diagnostic tool, it becomes a ministry of healing. As the Good Shepherd restores the soul, the attentive clinician restores the trust, dignity, and hope of the patient.

 

Auscultation remains a vital pathway, uniting clinical science with the healing art of listening. Its practice, structured, disciplined, and compassionate, reminds us that medicine is not only about discovering pathology but also about shepherding life with care. In the stillness of auscultation, the voice of both body and soul can be heard.

 

References

 

1. Laennec RTH. De l’Auscultation Médiate. Paris: J.-A. Brosson & J.-S. Chaudé; 1819.

 

2. Mangione S, Nieman LZ. Cardiac auscultatory skills of internal medicine and family practice trainees: a comparison of diagnostic proficiency. JAMA. 1997;278(9):717–22.

 

3. Vukanovic-Criley JM, et al. Competency in cardiac examination skills in medical students, trainees, physicians. Arch Intern Med. 2006;166(6):610–6.

 

4. Shaver JA. Cardiac auscultation: a glorious past—and it does have a future! Circulation. 1995;91(4):1256–9.

 

5. Roy D, Sargeant J. The disappearing art of auscultation: a call to action. Med Teach. 2012;34(7):568–70.

 

6. Chizner MA. Cardiac auscultation: rediscovering the lost art. Curr Probl Cardiol. 2008;33(7):326–408.

 

Is Cukur Manis or Mani Cai Safe for Consumption?

 Nutritional Anaemia and Hypotension Among Rural Malaysian Women: Investigating the Role of Sauropus androgynus (Cekur Manis)

by  Lim Ju Boo alias Lin Ru Wu

Abstract: 

This paper explores the relationship between dietary patterns in rural Malaysian villages and the prevalence of nutritional anaemia and hypotension among young women, with a specific focus on the widely consumed vegetable Sauropus androgynus (cekur manis). Through field studies and chemical analyses, a potential link was established between frequent consumption of this vegetable and observed low blood pressure. The phytochemical component papaverine, a vasodilator, was identified in the plant. This paper discusses the dual nature of S. androgynus as both a nutritional and potentially toxic plant, citing documented outbreaks of bronchiolitis obliterans in Taiwan and Japan from the raw consumption of the plant in large quantities. Recommendations for safe consumption and further public health implications are provided.

1. Introduction:  During medical research and health surveys conducted by my medical and nutrition team from the Institute for Medical Research from 1970 till mid 1990's in the villages of Malaysia, a recurring health problem among young women was observed, namely, frequent complaints of giddy spells, later correlated with nutritional anaemia and consistently low blood pressure. These women, often on nearly meatless diets, experienced chronic iron deficiency worsened by monthly menstrual blood loss.

Upon deeper investigation, it was discovered that many of these villagers consumed large quantities of a local leafy vegetable known as cekur manis (Sauropus androgynus), valued for its affordability, taste, and traditional health benefits, and easy to plant in their own village fields and compounds. 

Intrigued by the potential physiological effects of this plant, samples of cukur manis were collected by one of my colleagues from the National University of Malaysia (UKM), and sent  to the Dept. of Nutrition at Queen Elizabeth College (QEC), University of London where we once studied -  for chemical analysis. There at QEC they used their mass spectrometers and nuclear magnetic resonance (NMR) spectrometers to identify the  compound present. It turned out to be papaverine, a smooth muscle relaxant that has hypotensive properties. Of course we can also use other analytical procedures such as spectroscopy (UV-Vis, FTIR) and chromatography (GC-MS, HPLC-MS), but magnetic resonance (NMR) spectrometers is better, and we did not have that analytical instrument.  

An NMR spectrometer is huge and a complex instrument, not easily visualized without prior knowledge, nor is it easy to use,  but it's essentially a huge machine  that uses strong magnetic fields and radio waves to analyze the magnetic properties of atomic nuclei within a sample. 

NMR (Nuclear Magnetic Resonance) spectroscopy is a powerful tool for elucidating and identifying the molecular structure of a compound. It provides detailed information about the connectivity of atoms within a molecule, as well as their chemical environment, which helps in determining the overall structure.

While not  simple to use, modern benchtop NMR spectrometers have become more user-friendly, with integrated consoles and software to aid in data acquisition and interpretation.

We did not have an NMR spectrometer in Malaysia then in the 1970's, so we sent samples of cukur manis to scientists at the Department of Nutrition and in the Department of Chemistry at Queen Elizabeth College, University of London to help us identify the unknown compound that causes hypotension. The scientists at QEC identified it as papaverine.

2. Nutritional Composition and Traditional Use S. androgynus is commonly consumed in Southeast Asia, known locally as cekur manis (Malay), mani cai (Chinese), or sweet leaf. Rich in iron, protein, vitamins A, B, and C, calcium, potassium, and carotenoids, it has been used traditionally to:

• Promote lactation

• Support skin and eye health

• Improve vitality and digestion

3. Field Observations and Clinical Correlation In the studied villages, the majority of women consumed cekur manis in cooked form, often stir-fried. No cases of respiratory distress or lung disease were reported, but hypotension was consistently noted. This prompted the hypothesis that a phytochemical component in cekur manis might be acting as a vasodilator.

4. Phytochemical Analysis: As already mentioned, laboratory analysis confirmed the presence of papaverine, an opium-derived but non-narcotic alkaloid known for its ability to relax smooth muscle tissues, particularly those of blood vessels. Papaverine’s pharmacological actions include:

• Dilation of cerebral and coronary arteries

• Smooth muscle relaxation in the gastrointestinal and genitourinary tracts

• Temporary blood pressure lowering effects

Although once used in the management of vascular diseases, papaverine is no longer widely prescribed for hypertension due to its:

• Short duration of action

• Potential hepatotoxicity

• GI and CNS side effects

• Unpredictable pharmacokinetics

The naturally occurring papaverine in cekur manis likely explains the consistent hypotension observed in the villagers, compounded by anaemia from poor iron intake.

5. Toxicity Concerns and International Incidents Between the 1990s and early 2000s, Taiwan and Japan saw multiple cases of bronchiolitis obliterans, a rare and irreversible lung disease, linked to the excessive raw consumption of S. androgynus. Young women consumed large quantities of raw cekur manis in juices or smoothies, often for weight loss or to enhance lactation.

Over 100 cases in Taiwan required long-term oxygen therapy, some requiring lung transplants [Chen et al., 2000].

The suspected mechanism involves certain alkaloids and non-protein amino acids that induce immune-mediated inflammation and fibrotic scarring of bronchioles.

The specific compound in raw Sauropus androgynus (cukur manis) that causes bronchiolitis obliterans has not been definitely identified. However, it is believed that certain compounds within the plant, particularly in the aqueous fraction, may be responsible for inducing lung inflammation and tissue damage. Studies suggest that the aqueous fraction of S. androgynus may play a significant role in the development of the disease. 

Several compounds have been isolated from S. androgynus, including nucleosides,  flavonols, and lignan glycosides, none have been definitively pinpointed as the sole cause of bronchiolitis obliterans.

T-cell Mediated Immunity:

Research indicates that T-cell mediated immunity might be involved in the pathogenesis of lung damage, suggesting an immune response is triggered by the plant's compounds.

Crucially, no cases were associated with cooked cekur manis, suggesting the  toxic compounds is destroyed during cooking (heat-labile).  

6. Recommendations and Public Health Implications Given the dual nature of S. androgynus ,  as a nutrient-dense vegetable and a potential source of toxicity, public education is essential:

Encourage consumption in moderation and only in cooked form, bear in mind cekur manis is  known to be rich in beta-carotene, which is a precursor to vitamin A (retinol). This means that the body can convert the beta-carotene found in cekur manis into vitamin A. Studies have shown that cekur manis contains a high level of total carotenoids, which are converted to retinol equivalents (RE). 

Avoid large quantities of raw cekur manis, especially in juice or smoothie form. Continue research to identify the exact causative toxic compounds

7. Conclusion:

The study highlights how local diets, when examined in conjunction with phytochemical analysis, can reveal both therapeutic and harmful health effects. The vasodilatory property of papaverine in cooked S. androgynus may explain low blood pressure among rural Malaysian women, especially those also affected by anaemia. However, international cases of bronchiolitis obliterans from raw consumption underscore the need for caution. Traditional wisdom and modern science must work hand-in-hand to ensure safe dietary practices.

References:

1, Chen CH, Shih CL, et al. (2000). Sauropus androgynus-induced bronchiolitis obliterans in Taiwan: a review of epidemiology, clinical presentations, and pathogenesis. Am J Respir Crit Care Med, 161(4): 1241–1246. PMID: 10764302

2. Ismail A, et al. (2000). Nutrient composition of selected indigenous vegetables in Malaysia. Food Chemistry, 68: 51–59.

3. Wong KC, Tan GL. (1995). Chemical constituents and biological activities of Sauropus androgynus. Natural Product Communications, 2(6): 199–204.

4. Wu CC, et al. (1997). Obliterative bronchiolitis associated with consumption of Sauropus androgynus in Taiwan. Lancet, 349: 1306.

5. Liu GY, et al. (2006). Papaverine and its pharmacological applications: past, present and future. International Journal of Clinical Pharmacology and Therapeutics, 44(9): 480–488.

The Medicinal Values of Garlic - from Clove to Circulation

 Title: The Biochemistry and Pharmacology of Garlic: From Clove to Circulation

by: Lin Ru Wu alias Lim Ju Boo

 

In the mid 1960's I was doing my postgraduate in Nutrition at the University of London when one of my professors mentioned about the medicinal values of garlic. Today, I like to share further knowledge I gained  there about this valuable medicinal  clove 

Abstract:

Garlic (Allium sativum) has been revered since antiquity for its culinary and medicinal properties. This paper explores the biochemical transformation of garlic's sulfur compounds, particularly allicin and ajoene, through mechanical processing, digestion, and hepatic metabolism. It discusses the pharmacologically active derivatives of garlic, their bioavailability, and the evidence-based therapeutic doses. By synthesizing findings across food chemistry, enzymology, and clinical pharmacology, this work aims to serve as a concise but comprehensive resource for doctors, nutritionists,  healthcare enthusiasts and scholars

1. Introduction:

Garlic is widely recognized for its diverse medicinal applications, including antimicrobial, cardiovascular, and anticancer effects. These properties are attributed to sulfur-containing compounds formed upon cellular disruption of garlic tissues. While traditional knowledge praises garlic's benefits, understanding the journey of its bio-actives from raw clove to systemic circulation requires a multidisciplinary approach.

2. Allicin Formation: The Moment of Activation

Allicin is not present in intact garlic cloves. Upon mincing or crushing, the enzyme alliinase converts the stable compound alliin into allicin within 5 to 10 minutes. This enzymatic reaction is highly sensitive to:

• Heat (>60°C), which denatures alliinase

• Acidity, which can reduce enzyme efficiency

Reaction Pathway: Alliin (S-allyl-L-cysteine sulfoxide) + Alliinase → Allicin (diallyl thiosulfinate)

Waiting 10 minutes after crushing allows maximal allicin formation before further cooking or ingestion.

3. Stability and Degradation of Allicin

Allicin is unstable, reactive, and decomposes quickly into secondary sulphur compounds, including:

• Ajoene (anti-platelet, antifungal)

• Diallyl disulfide (DADS)

• Diallyl trisulfide (DATS)

• S-allyl cysteine (SAC) (stable, bioavailable in aged garlic)

Heat, time, and pH conditions all influence the breakdown pathway.

4. Oral Processing vs Mechanical Mincing

Chewing garlic activates alliinase, but swallowing too quickly reduces time for full allicin conversion. Saliva does not appear to inactivate alliinase significantly, but the enzymatic activity is more reliable in a controlled setting (e.g., mincing and waiting 10 minutes).

5. Gastrointestinal and Hepatic Fate

In the digestive tract:

• Allicin is mostly degraded in the stomach
• Derivatives like DADS, DATS, ajoene, and SAC survive and are absorbed

In the liver:

• Some compounds are metabolized but retain activity

• SAC is especially bioavailable and used in standardized supplements

6. Pharmacological Activity and Effective Doses

Compound	Effective Dose	Activity
Allicin	20–50        mg/day	Antimicrobial,                       antihypertensive
Ajoene	~10–25         mg/day	Antithrombotic,                   antifungal
SAC	Varies	Antioxidant, anti-                 inflammatory

Garlic supplements are typically standardized to 1.3% allicin content or 3.6 mg per 600 mg tablet. But this value may not be stable on storage as for garlic pills. I shall talk on this later.  

7. Preparation Guidelines for Maximum Medicinal Value

Method	Allicin Yield	Notes
Mince + wait 10 min + consume raw	Maximum	Best for medicinal use
Chewing raw garlic	Moderate	Faster ingestion limits yield
Cooking after 10 min rest	Mild	Low heat preserves some value
Aged garlic extract	High (SAC)	Ideal for long-term supplementation

8. Conclusion

While allicin itself is ephemeral, its derivatives may or may not persist and contribute meaningfully to garlic's therapeutic potential. For instance, from the very beginning I mentioned that in the mid 1960's when I was doing my postgraduate in Nutrition at the University of London when one of my professors mentioned about the medicinal values of garlic. But he also told us that they took over two dozens different types of garlic pills manufactured by various companies from various parts of the world and analyzed them for the presence of ajoene, the derivative of allicin since allicin is not stable. What the researchers at London University found was, even ajoene which was supposed to be more stable was not present in any of those hundreds of garlic pills. This implied that even the derivatives of allicin - ajoene is not stable when the garlic was processed into pill form or when stored in a bottle for sales. Probably garlic pills were  just oils - like any vegetable oil with no medicinal values in them?  

My strong advised is, when raw garlic has been minced or crushed, wait for at least 10 minutes for the enzyme alliinase to release the allicin and consume immediately - not longer than a few hours later. We are unsure if storing the minced raw garlic in a refrigerator will retain its medicinal values - allicin and its derivatives - DADS, DATS, ajoene, and SAC, since as far as I know, no study has been done on this. 

Understanding garlic as a sequence of biochemical transformations, from mechanical activation to hepatic metabolism, enables more effective use of this ancient botanical medicine.

References

1. Amagase H, Petesch BL, Matsuura H, Kasuga S, Itakura Y. Intake of garlic and its bioactive components. J Nutr. 2001 Mar;131(3s):955S-962S.

2. Lawson LD, Wang ZJ. Allicin and allicin-derived garlic compounds increase breath acetone through allyl methyl sulfide: Use in measuring functional allicin in garlic. J Agric Food Chem. 2005;53(6):1974-1983.

3. Dirsch VM, Kiemer AK, Wagner H, Vollmar AM. Effect of allicin and ajoene, two compounds of garlic, on inducible nitric oxide synthase. Atherosclerosis. 1998;139(2):333-339.

4. Rahman K. Effects of garlic on platelet biochemistry and physiology. Mol Nutr Food Res. 2007;51(11):1335-1344.

5. Iciek M, Kwiecien I, Wlodek L. Biological properties of garlic and garlic-derived organosulfur compounds. Environ Mol Mutagen. 2009;50(3):247-265.

Acknowledgments:

 Special gratitude to my friend and colleague, Professor Sage for his additional inputs that has inspired me to write this paper

Medicines in Mushrooms

 A paper  presented by Professor Dr Ong Wei Yi from the National University of Singapore and his colleagues on 

"Ergothioneine Treatment Ameliorates the Pathological
Phenotypes of Parkinson's Disease Models" 

https://sg.docworkspace.com/d/sIDLzzKWFAbncjcUG?sa=601.1037

This paper was presented at the 8th International Anatomical Sciences and Cell Biology Conference on 14 and 15th August, 2025 in Kuala Lumpur. Malaysia 

Nature’s Healing Arsenal in Foods

 

Nature’s Healing Arsenal: Functional Foods and Phytochemicals in Disease Prevention and Therapy

by: 

Nutritionist Lim Ju Boo and Professor Dr M Sage MD PhD  

Abstract

Functional foods are increasingly recognized for their capacity to promote health and reduce the risk of chronic diseases. Beyond providing essential nutrients, these foods contain hundreds, if not thousands, of phytochemicals and bioactive compounds. These compounds, including ergothioneine in mushrooms, sulforaphane in broccoli sprouts, curcumin in turmeric, and catechins in green tea, play vital roles in modulating oxidative stress, inflammation, metabolism, and immunity. This article provides a comprehensive overview of selected functional foods and their phytochemicals, with emphasis on mechanisms of action, disease-preventive roles, and evidence from clinical studies.

Introduction

The concept of functional foods extends beyond basic nutrition. These are everyday foods that confer specific physiological benefits or reduce disease risk, thanks to their natural bioactive components. Phytochemicals, a diverse class of plant- and microbe-derived compounds, exert health-promoting effects by interacting with cellular pathways. Unlike vitamins and minerals, phytochemicals are not considered essential nutrients, yet their presence in the human diet is associated with reduced risk of non-communicable diseases such as cardiovascular disease, cancer, diabetes, and neurodegeneration.

Among the wide array of bioactives, certain compounds stand out due to their robust mechanistic evidence and clinical evaluation. These include ergothioneine and β‑glucans from mushrooms, sulforaphane from cruciferous vegetables, curcumin from turmeric, epigallocatechin gallate (EGCG) from green tea, organosulfur compounds from garlic, lycopene from tomatoes, and isoflavones from soy. Their health effects are mediated by key molecular pathways including activation of antioxidant defenses, suppression of pro-inflammatory signals, modulation of lipid and glucose metabolism, and regulation of immune responses.

Ergothioneine: The Longevity Molecule from Mushrooms

Ergothioneine is a sulphur-containing antioxidant produced by fungi and some bacteria, but not by plants or animals. Humans acquire it exclusively through diet, with mushrooms being the richest source. Ergothioneine is transported into cells by the specific transporter OCTN1 (SLC22A4) and preferentially accumulates in tissues exposed to high oxidative stress such as the liver, kidneys, brain, and eyes. It functions as a cytoprotectant, scavenging reactive oxygen species, preserving mitochondrial function, and reducing inflammation.

Recent studies suggest that lower plasma ergothioneine levels are associated with faster cognitive decline in older adults, raising the possibility that it may be a conditionally essential nutrient. Regular consumption of a variety of mushrooms, such as shiitake, oyster, or king trumpet mushrooms, can help increase ergothioneine intake and simultaneously deliver β‑glucans with immune-modulating effects (Tian et al., 2023; Fu et al., 2022).

β‑Glucans: Immune and Metabolic Regulators

β‑Glucans are polysaccharides found in both cereals (such as oats and barley) and fungi (mushrooms and yeast). Their health benefits differ depending on the source. Cereal-derived β‑glucans form viscous gels in the gut, lowering LDL cholesterol by reducing intestinal absorption of cholesterol and increasing bile acid excretion. Large meta-analyses consistently show that consumption of 3 g/day of oat β‑glucan significantly reduces LDL cholesterol and improves lipid profiles (Yu et al., 2022; Noronha et al., 2023).

Fungal β‑glucans, on the other hand, interact with innate immune receptors such as Dectin‑1 and Toll-like receptors, priming immune cells and enhancing their pathogen-fighting ability. This “trained immunity” effect has implications for infection control and oncology, with β‑glucan supplements from mushrooms like shiitake and reishi under active clinical investigation (Cerletti et al., 2021).

Sulforaphane: A Cruciferous Defender

Broccoli sprouts are an exceptional source of sulforaphane, an isothiocyanate derived from glucoraphanin through enzymatic action by myrosinase. Sulforaphane potently activates the Nrf2 pathway, which regulates the expression of antioxidant and detoxification enzymes such as heme oxygenase‑1 and glutathione S‑transferases. In doing so, it enhances the body’s defense against oxidative damage and inflammation. Sulforaphane also influences mitochondrial function and has shown neuroprotective and anticancer properties in experimental models. Human trials indicate promising biomarker improvements, although outcome data remain mixed, often due to variability in preparation and bioavailability (Yan et al., 2024; Bessetti et al., 2025).

Curcumin: Golden Spice with Broad Potential

Curcumin, the active pigment of turmeric, is a pleiotropic molecule that targets multiple signaling pathways. It downregulates NF‑κB, a master regulator of inflammation, and influences epigenetic enzymes involved in gene regulation. Clinical studies and meta-analyses have demonstrated its efficacy in reducing C-reactive protein (CRP), tumor necrosis factor‑α, and markers of oxidative stress. Curcumin has shown benefits in conditions such as arthritis, metabolic syndrome, and certain cancers. However, its low bioavailability has limited its clinical translation, and modern formulations using piperine, phospholipids, or nanoparticles are helping to overcome this challenge (Dehzad et al., 2023; Lee et al., 2024).

Epigallocatechin Gallate (EGCG): Green Tea’s Polyphenolic Star

Green tea is rich in catechins, with EGCG being the most studied. EGCG influences multiple signaling cascades including AMPK activation, PI3K/Akt/mTOR inhibition, and suppression of NF‑κB. It exhibits anti-inflammatory, cardioprotective, and anticancer properties. Clinical evidence supports its role in improving cardiovascular risk markers and as a potential adjunct in oncology. However, caution is warranted with high-dose extracts due to rare cases of hepatotoxicity, whereas brewed green tea remains a safe and effective option (Capasso et al., 2025).

Garlic Organosulfur Compounds: Traditional Medicine with Modern Proof

Garlic has been used for centuries as both food and medicine. Its organosulfur compounds, such as allicin, diallyl disulfide, and S‑allyl‑cysteine, exhibit antimicrobial, antioxidant, and cardiovascular benefits. Mechanistically, these compounds act as hydrogen sulfide donors, reduce platelet aggregation, and modulate lipid metabolism. Clinical studies support modest reductions in blood pressure and cholesterol with garlic consumption, with effects varying by preparation type (Seki et al., 2025; El‑Saadony et al., 2024).

Lycopene: The Tomato’s Red Shield

Lycopene, a carotenoid found abundantly in tomatoes, is a powerful singlet oxygen quencher. It accumulates in tissues such as the prostate and adrenal glands, influencing signaling pathways including insulin-like growth factor‑1. Observational studies and meta-analyses have linked higher lycopene intake to reduced cancer risk, particularly prostate cancer, and lower overall cancer mortality. Lycopene absorption is enhanced by cooking and co-consumption with oils, making tomato-based dishes with olive oil particularly beneficial (Balali et al., 2025).

Isoflavones: Soy’s Phytoestrogenic Benefits

Soy isoflavones, particularly genistein and daidzein, act as selective estrogen receptor β agonists. They modulate tyrosine kinase activity and influence epigenetic regulation. Clinical evidence supports their role in reducing menopausal symptoms, improving bone health, and supporting cardiovascular function. Their impact on hormone-sensitive cancers is complex and context-dependent, requiring individualized dietary advice (Sharifi‑Rad et al., 2021; Zhang et al., 2025).

Summary Conclusion: 

Functional foods and their phytochemicals form a natural arsenal against chronic disease. They modulate oxidative stress, inflammation, immune defense, and metabolic regulation, offering preventive and adjunctive benefits. A food-first approach, emphasizing mushrooms, crucifers, turmeric, green tea, garlic, tomatoes, soy, oats, and barley, provides a practical and safe way to harness these benefits. While supplements may be useful in targeted cases, dietary integration remains the most sustainable strategy. More research is needed to define optimal intake levels, bioavailability strategies, and long-term clinical outcomes, but the existing evidence strongly supports their role in human health.

References

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Disclaimer: This article is for educational purposes only and is not a substitute for individualized medical advice. Always consult healthcare professionals such as a qualified nutritionist or a dietician before making major dietary or supplement changes.