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September 2025,Volume 47, No.3
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Internet
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What’s in the web for family physicians − A critical review of contemporary food and nutrition mythsSio-pan Chan 陳少斌，Wilbert WB Wong 王維斌，Alfred KY Tang 鄧權恩
IntroductionWestern medicine has long relied on a reductionist approach – identifying specific causative agents and eliminating them through targeted interventions such as drugs or vaccines. While effective for infectious diseases and single aetiology diseases, this approach is less successful in managing multifactorial conditions like metabolic syndrome, type 2 diabetes, and cardiovascular disease, where diet and lifestyle play critical roles. Despite growing recognition of the importance of nutrition, the field remains fraught with controversy, often fuelled by conflicting studies, some of which are industry-funded and yield questionable results. A classic example is the decades-long debate over eggs and their link to coronary heart disease. This review critically examines prevalent food myths, particularly those amplified by social media, and aims to clarify misconceptions by focusing on independent, peer-reviewed research while excluding industry-sponsored data. Eggs Myth Revisited
Eggs have long been a nutritional paradox. On one hand, they are vilified for their cholesterol content; on the other, they are celebrated for their dense nutrient profile. Let’s look at what recent studies say. Eggs are rich in choline, a precursor to acetylcholine – a neurotransmitter essential for memory and muscle control. Studies suggest that higher choline intake is associated with improved cognitive performance and reduced risk of neurodegenerative diseases. Additionally, eggs contain lutein and zeaxanthin, carotenoids that accumulate in the brain and retina, potentially enhancing visual processing and cognitive function. The fear surrounding dietary cholesterol stems from older studies that linked it to cardiovascular disease. However, more recent research indicates that for most people, dietary cholesterol has a modest impact on blood cholesterol levels. The real concern lies in oxidised cholesterol, which can form during high-heat cooking methods like frying. Oxidised lipids are implicated in inflammation and atherosclerosis, both of which can impair cerebral blood flow and cognitive function. Eggs, when consumed in moderation and prepared using gentle cooking methods (e.g., boiling or poaching), can be a valuable part of a brain-healthy diet. Red Meat and Cancer
Red meat is among the most nutrient-dense food. In addition to being a rich source of protein, it also provides significant amounts of iron, zinc, and B vitamins. However, red meat consumption is often associated with cancer and cardiovascular disease. The following represents a more evidence-based view on red meat. Most studies that associate red meat with negative health outcomes focus on processed meats – bacon, sausages, and deli meats – which contain nitrates, nitrites, and other preservatives. These compounds can form nitrosamines, known carcinogens, especially when cooked at high temperatures. In contrast, unprocessed red meat, such as grass-fed beef or lamb, contains higher levels of omega-3 fatty acids and conjugated linoleic acid (CLA), both of which have anti-inflammatory properties. The method of preparation also matters: grilling and frying can produce heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs), which are linked to cancer risk. Slow-cooking or stewing minimises formation of these compounds. Red meat provides heme iron, which is more bioavailable than the non-heme iron found in plant sources. Iron deficiency is a known contributor to cognitive impairment, especially in children and older adults. Unprocessed red meat, when consumed in moderation and prepared using low-heat methods, can support brain health. The blanket demonisation of red meat ignores important distinctions in quality and preparation. Coffee and Health
Coffee is one of the most widely consumed beverages globally, offering both significant health benefits and potential risks. Its principal bioactive compound, caffeine, acts as a central nervous system stimulant, enhancing alertness, cognitive performance, and mood. Moderate consumption – typically two to four cups per day – has been associated with a reduced risk of neurodegenerative disorders such as Alzheimer’s and Parkinson’s disease, largely due to coffee’s antioxidant and anti-inflammatory properties. Additionally, polyphenols present in coffee may confer neuroprotective effects by mitigating oxidative stress and improving vascular function. Individual variability in caffeine response is influenced by genetic factors. Polymorphisms in genes such as CYP1A2, which regulate caffeine metabolism, determine the rate of clearance from the body. Individuals with slower metabolic rates may be more susceptible to adverse effects, including anxiety, insomnia, cardiac arrhythmias, palpitations, and other cardiovascular symptoms, underscoring the need for personalised intake. The brewing methods used can significantly affect the health impact of coffee. Unfiltered preparations, such as French press and espresso, contain diterpenes like cafestol and kahweol, which may elevate low density lipoprotein (LDL) cholesterol. In contrast, filtered brewing techniques reduce these compounds, rendering them a preferable option for cardiovascular health. Recent studies have shown that decaffeinated coffee retains many beneficial antioxidants and polyphenols but contains much less caffeine than regular coffee. Thus, it makes a valuable alternative for individuals sensitive to caffeine. Organic Food
Organic food is often marketed as a healthier alternative, but does it truly offer superior benefits for health? One of the strongest arguments for organic produce is reduced exposure to pesticides, some of which are known neurotoxins. Chronic exposure to organophosphates, for example, has been linked to developmental delays and cognitive deficits in children. Organic farming standards prohibit the use of many synthetic pesticides, potentially lowering this risk. Meta-analyses show that organic produce may contain slightly higher levels of antioxidants and polyphenols, but the differences are often modest. The impact on long-term brain health remains inconclusive. Organic farming tends to be more sustainable, promoting soil health and biodiversity. However, organic products are often more expensive, which can limit accessibility. From a public health perspective, encouraging higher fruit and vegetable intake – regardless of farming method – may be more impactful than promoting organic exclusivity. Organic food may offer modest neuroprotective benefits due to lower pesticide exposure, but it is not a panacea. Prioritising variety, freshness, and preparation is more important than the organic label alone. Seed Oils Controversy
Seed oils – like canola, soybean, and sunflower – have faced criticism for allegedly promoting inflammation and chronic disease. These oils are rich in omega-6 polyunsaturated fatty acids (PUFAs), especially linoleic acid. While omega-6s are essential, an imbalance with omega-3s may contribute to a pro-inflammatory state, which is linked to neurodegeneration and cognitive decline. However, their inflammatory potential depends on overall dietary context. When consumed with sufficient omega-3s and antioxidants, seed oils may not pose significant harm. A key concern is their oxidative stability: heating seed oils to high temperatures, particularly during deep frying, can produce toxic compounds like aldehydes and lipid peroxides that may impair brain function. In contrast, cold-pressed or minimally processed oils used in low-heat cooking or dressings carry less risk. Additionally, many commercial seed oils undergo chemical extraction and deodorisation, potentially introducing trace contaminants. Opting for expellerpressed or organic versions can reduce this risk. Seed oils aren’t inherently harmful. Their health impact hinges on processing, cooking method, and dietary balance. Blanket condemnation oversimplifies a nuanced issue – context matters when evaluating their role in nutrition. Frozen Food: Nutritional and Practical Value
Frozen fruits and vegetables are often dismissed as nutritionally inferior to fresh produce, yet this perception overlooks their scientific and practical benefits. Frozen items are typically harvested at peak ripeness and flash-frozen within hours, preserving vitamins (A, C), antioxidants, and fiber more effectively than fresh produce subjected to prolonged transport and storage. Studies confirm that frozen produce often matches or exceeds the nutrient density of “fresh” counterparts after just five days of refrigeration. While pre-freezing blanching may result in the partial loss of water-soluble nutrients, notably vitamin C, advancements in steam-blanching techniques have substantially minimised these nutrient reductions. In comparison, fresh produce is subject to ongoing nutrient degradation through enzymatic activity and oxidative processes. The economic accessibility, yearround availability, and decreased perishability of frozen produce contribute meaningfully to sustained dietary compliance, particularly within food-insecure populations. Advocating for the inclusion of both fresh and frozen varieties – while underscoring the importance of selecting frozen options free from added sugars and sauces – challenges elitist narratives and fosters a more equitable framework for nutritional health. The Gluten-Free Diet Hype
Gluten-free (GF) diets are essential for the 1% with celiac disease or gluten sensitivity but offer no proven benefits for the general population. Non-celiac individuals adopting GF diets risk deficiencies in fiber, iron, and B vitamins due to refined flours in processed GF foods. Strict adherence is challenging and can cause psychological burdens without medical justification. Contrary to social media claims, no evidence supports gluten avoidance for weight loss or autism mitigation. Saturated Fats: Beyond the Demonisation
Controlled trials (1) show replacing saturated fat (SFA) with polyunsaturated fat (PUFA) lowers total and LDL cholesterol and improves the total/ HDL ratio; replacing SFA with carbohydrates lowers HDL and raises triglycerides. A meta‑analysis of prospective cohorts (2) found no consistent association between SFA intake and coronary heart disease or total CVD. The large multi‑country PURE cohort (3) reported that higher total fat - including SFA - was not linked to greater CVD and was associated with lower all‑cause mortality, while higher carbohydrate intake was linked to higher mortality. Overall: effects of saturated fat depend on what replaces it and on overall dietary context; replacing SFA with PUFA/MUFA and whole foods is preferable to replacing it with refined carbohydrates. Calorie Counting: Science or Obsession?
The classic weight-loss formula – calories in = calories out – is rooted in thermodynamics, but modern science reveals it is only part of the story. While calorie tracking can aid weight loss, it often oversimplifies a complex biological system. Gut microbiome research shows that individuals absorb and metabolise calories differently, depending on microbial diversity and food quality. Fiber-rich, whole foods engage the microbiome, reducing calorie absorption and improving satiety. Meanwhile, processed foods bypass microbial processing, making calories more bioavailable. Studies also show that time-restricted eating and macronutrient shifts can rival calorie counting in effectiveness. So, while calorie awareness is useful, obsessing over numbers may ignore deeper metabolic drivers. True weight management lies in nourishing the body – not just tallying its fuel.
Sio-pan Chan,
MBBS (HK), DFM (HKCU), FHKFP, FHKAM (Family Medicine)
Correspondence to:
Dr. Sio-pan Chan, SureCare Medical Centre (CWB), Room 1116-7,
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