Despite Thousands of Years of Belief, No Evidence Cold is Bad for Kidneys

What Traditional Chinese Medicine calls a Kidney includes more than physical kidneys.

Despite thousands of years of belief in Traditional Chinese Medicine (TCM) that cold harms the kidneys—particularly through the concept of Kidney Yin deficiency linked to cold exposure—modern research finds no direct evidence that cold damages the kidneys. This misconception in TCM arose from ancient observations and philosophical frameworks that interpreted patterns of illness in terms of Yin and Yang balance rather than empirical anatomical or physiological studies.

The theory of cold and hot properties in TCM, first recorded in the Shennong Bencao Jing during the Han Dynasty (200–300 AD), classified diseases and treatments based on whether symptoms and substances were “cold” or “hot.” Cold was seen as a Yin pathogen that could invade the body, weaken Kidney Yang, and thereby impair vital functions such as warmth generation, fluid regulation, and bone health—functions traditionally attributed to the kidneys in the TCM framework. Because the kidneys were considered the root of Yin and Yang in the body, and Yang represented warmth and vitality, cold exposure was thought to easily damage kidney Yang, leading to symptoms like pain, cold limbs, nocturia, and impotence. Consequently, people were advised to protect their kidneys from cold by eating warming foods and practicing exercise to preserve Yang energy [1][5][6].

It should be understood that TCM’s holistic concept of the kidney differs substantially from the biomedical organ. In TCM, the kidney encompasses a broad functional system regulating growth, reproduction, water metabolism, reproductive health, bone health, and vital essence (Jing). According to Traditional Chinese Medicine (TCM), the concept of the “kidney” (腎, shèn) differs significantly from the anatomical kidneys understood in modern Western medicine. While TCM locates the kidneys as paired organs in the lumbar region, TCM extends the definition far beyond the physical structures to encompass a broad set of functional and energetic roles within the body. Rather than being limited to filtering blood and producing urine, the TCM kidney system governs vital processes including bone strength, auditory function, nervous system regulation, and even aspects of the spirit or will-power (Zhi).

There are some reasons recognized by current (Western) biomedical understanding for these connections. For example, while the biomedical kidneys themselves do not directly provide bone strength, they play a crucial role in maintaining bone health by regulating mineral and hormone balance—especially calcium, phosphate, vitamin D, and parathyroid hormone—that affects bone remodeling and density. In chronic kidney disease (CKD), impaired kidney function leads to mineral and bone disorders marked by imbalances in calcium and phosphorus, resulting in weakened bones and increased fracture risk. Thus, kidney dysfunction indirectly causes bone loss and fragility by disrupting the homeostasis necessary for healthy bone formation and maintenance, but the kidneys are not the physical source of bone strength.

This system was understood symbolically and based on clinical symptom patterns rather than direct observation, which limited TCM’s ability to distinguish actual kidney tissue damage from systemic or functional imbalances. For centuries, TCM diagnoses and treatments were based on the balance of Yin and Yang, cold and hot syndromes, making it difficult to empirically challenge established dogma [6][8].

The failure for thousands of years to scientifically refute cold’s effect on the kidney stems from this fundamentally different worldview. The medical texts emphasized careful matching of “cold” and “hot” medicines to syndromes for effective and safe treatment. Violating these principles risked exacerbating symptoms, reinforcing belief in cold-induced kidney weakness even where physiological evidence was lacking [1][6].

By contrast, modern biomedical studies assess kidney health through direct measures like glomerular filtration rate and biomarkers, showing that extreme heat rather than cold presents a clearer risk to kidney function. Cold exposure mainly causes vascular constriction, which can raise blood pressure but does not directly damage renal tissue. Increased kidney-related morbidity in winter often arises from secondary factors—dehydration, infection, electrolyte imbalances—not from cold itself [PMC 2024; J-Stage 2024].

Large-scale clinical data analyzed at Seoul St. Mary’s Hospital found that renal function, measured by estimated glomerular filtration rate (eGFR), declines linearly when temperatures rise above approximately 25°C. In contrast, while some correlation between very low temperatures (below −10°C) and kidney function decrease was observed, the results were not statistically significant, suggesting cold’s effect on kidney function is limited or indirect.

The apparent increased mortality related to kidney disease in cold seasons likely stems from indirect factors rather than direct cold injury to the kidneys. These include dehydration due to lower fluid intake, electrolyte imbalances like winter-related hyperkalemia, and elevated blood pressure caused by cold-induced vasoconstriction. Such physiological stresses can worsen existing kidney disease or contribute to acute kidney injury, especially in vulnerable populations such as the elderly or those with chronic kidney conditions. Moreover, cold seasons are associated with higher rates of infections and cardiovascular events that can indirectly affect kidney health.

Importantly, studies from Japan and the UK indicate that acute kidney injury (AKI) incidence and severity may increase during winter months, but this relates more to systemic factors like blood pressure variation and fluid management than cold exposure per se. Additionally, indoor cold exposure, common in some regions, can worsen symptoms such as nocturia in the elderly but does not constitute direct kidney damage.

In summary, TCM’s traditional view that cold harms the kidneys arose from early medical philosophy linking cold Yin pathogen to Kidney Yang deficiency, without the benefit of modern anatomy or physiology. While this system offered practical treatment frameworks aligned with symptom patterns, it was limited in distinguishing cold’s actual effects on kidney tissue. Today, scientific evidence clarifies that cold is not inherently harmful to kidneys, helping bridge ancient wisdom and modern medicine.

Traditional Chinese Medicine (TCM) is a complex medical system developed over thousands of years based on empirical observations and philosophical concepts like Qi and Yin-Yang rather than on modern scientific methods[12][16]. The majority of its core theories and treatments lack robust, high-quality scientific evidence according to current research standards, leading many mainstream scientists to consider much of TCM pseudoscientific[11][12][15]. While some components—such as acupuncture and certain herbal products—have shown potential benefits supported by clinical studies, the overall effectiveness and mechanisms of many TCM practices remain inconclusive, with safety and consistency concerns in herbal products[13][17]. For example, TCM diagnostics like detecting pregnancy through pulse examination have been scientifically disproved[11]. Thus, although TCM integrates traditional cultural knowledge with empirical practice, it has not been fully validated through the lens of evidence-based medicine widely accepted in Western healthcare systems[15][16].

Yes, the truth is that at least one claim by TCM has been disproven. This does not mean that others have, of course, but telling pregnancy from a woman’s pulse alone is baloney. A high-profile challenge was issued by Dr. Ning Fanggang, a doctor at Beijing Jishuitan Hospital, who offered a substantial cash prize (100,000 yuan) to any Traditional Chinese Medicine (TCM) practitioner who could correctly diagnose pregnancy by pulse reading alone with at least 80% accuracy. This challenge was designed specifically to test TCM’s long-held claim that pregnancy can be reliably detected through pulse diagnosis, a method practiced for over two millennia.

Despite the cultural respect and popularity of TCM, the challenge highlighted the inability of practitioners to meet this accuracy threshold under controlled conditions. For example, Dr. Lu Jilai, a well-known TCM practitioner, attempted the test but failed the blindfolded experimental setup, knocking serious doubt on the practical reliability of pulse diagnosis for pregnancy. Skepticism grows because pulse reading depends heavily on subjective interpretation, lacks reproducibility, and cannot isolate pregnancy confidently without other signs.

Scientific studies have analyzed pulse characteristics in pregnant women and found some statistical differences in pulse spectrum or entropy at different pregnancy stages. However, these subtle measurable changes do not translate into effective, practical pregnancy diagnosis solely by pulse—much less at the 80% accuracy required in the challenge. Thus, while TCM theory claims that the cubit pulse changes during pregnancy, scientific testing has shown that pulse diagnosis alone simply does not work as a method to detect pregnancy.

Across cultures, including in medicine, the acceptance of authority without rigorous evidence can lead to ineffective or even harmful practices. When cultural beliefs or traditions are treated as unquestionable truths rather than ideas subject to scientific scrutiny, it can prevent progress, delay proper diagnosis and treatment, and undermine trust in genuinely effective healthcare. A healthy medical system—regardless of cultural context—should encourage critical thinking, evidence-based evaluation, and transparency, ensuring that claims are validated rather than accepted on authority alone. This helps protect patients and promotes continual improvement in health outcomes.

What Is Good and What is Bad for Kidneys?

Here is a concise summary of what science shows are among the worst and best foods and habits for kidney health, based on current evidence:

Worst for Kidneys

High Sodium (Salt): Excess sodium raises blood pressure, increases kidney workload, and accelerates damage. Processed foods, canned soups, salty snacks, and excessive salt added at the table should be avoided or limited[22][23][26]. Some complex studies suggest the relation between sodium intake and kidney outcomes can vary somewhat based on proteinuria levels and individual patient conditions, but the dominant consensus remains that reducing excessive sodium is protective for kidney health and slows CKD progression[31].
Dark-Colored Sodas and Sugary Drinks: These contain phosphorus additives and sugar, both harmful to kidneys. Soda consumption links to increased risk of chronic kidney disease (CKD)[21][23][24][27].
Processed and Ultraprocessed Foods: High in additives, sodium, phosphorus, sugar, and advanced glycation end products (AGEs), processed foods increase oxidative stress and kidney damage risk[22][25].
Excessive Animal Protein: Red and processed meats put extra strain on kidneys and correlate with a higher CKD risk. High protein intake can overburden impaired kidneys[23][24][28].
Overuse of NSAIDs and Certain Drugs: Regular use of nonsteroidal anti-inflammatory drugs (e.g., ibuprofen), some proton pump inhibitors, and recreational drugs may cause kidney injury[22][23].
Excess Potassium and Phosphorus-Rich Foods: In kidney disease, foods very high in potassium (bananas, oranges, dried fruits) and phosphorus (processed foods, dairy) can worsen kidney function and mineral balance[21][26][27][29].
Heavy Alcohol Use: Chronic heavy drinking increases risk of kidney damage and disease progression[23].
Dehydration: Not drinking enough water impairs kidney function and increases injury risk[23]. Drinking about 1.0 to 1.5 liters of plain water daily is often considered beneficial for kidney health, while both very low (<0.5 L) and very high (>2.0 L) plain water intakes have been associated with risks in some populations. Aim for urine that is straw-colored or pale; darker urine usually indicates insufficient hydration and a higher risk of kidney stress. Hydration needs depend on age, body size, climate, activity level, pregnancy or breastfeeding status, and health conditions. For example, physically active individuals or those exposed to hot environments need more fluids

Best for Kidneys

Adequate Hydration: Drinking enough water supports kidney filtration and helps prevent kidney stones[23][26].
Moderate, Quality Protein: Favor plant proteins (beans, legumes, nuts) and fish or low-fat dairy over red and processed meats, to reduce kidney stress without compromising nutrition[24][28][29].
Fruits and Vegetables: Especially colorful, nutrient-dense produce low in potassium if kidney disease is advanced; they provide antioxidants and promote overall health[24][26].
Low Sodium, Whole Foods: Preparing meals at home with minimal added salt and emphasizing whole grains, fresh produce, and unprocessed foods benefits kidney health[22][24][26].
Limiting Added Sugars: Avoiding foods and drinks with high added sugar reduces kidney strain and risk of diabetes, a major CKD cause[21][24].
Controlling Blood Pressure and Diabetes: Lifestyle changes that maintain healthy blood sugar and blood pressure indirectly protect kidneys, the major damage targets of these conditions[23][26].

Key Habits to Protect Kidney Health

– Avoid frequent or excessive use of over-the-counter painkillers (NSAIDs).
– Reduce consumption of processed and fast foods.
– Maintain adequate but not excessive hydration.
– Favor plant-based foods and lean proteins.
– Limit intake of phosphate additives common in processed foods and colas.
– Monitor potassium and phosphorus intake if CKD is diagnosed.
– Avoid heavy alcohol consumption and recreational drugs impacting kidney function.

Summary

Kidneys thrive with an anti-inflammatory, low-sodium, nutrient-dense diet that avoids highly processed foods, excess animal protein, and harmful additives. Good hydration and prudent use of medications also play key roles. Conversely, diets high in salt, processed meats, sodas, and refined foods accelerate kidney damage and increase disease risk.

References:

NIDDK – Healthy Eating for CKD (2025)
PMC, J-Stage — Modern temperature and kidney function studies (2024)
National Kidney Foundation – Habits That Harm Kidneys (2024)
WebMD – Surprising Things That Can Hurt Your Kidneys (2024)
Piedmont Healthcare – Kidney-Damaging Foods (2024)
Medical News Today – Foods Bad for Kidneys (2024)
Healthline – Foods to Avoid With Kidney Disease (2023)
PMC – Ultraprocessed Foods and Chronic Kidney Disease (2023)
Tian et al. Traditional Chinese Medicine in Chronic Kidney Disease Treatment. Frontiers in Pharmacology (2022)
Liu J, et al. Cold and Hot Properties of Traditional Chinese Medicines. PMC (2021)
Oxford Academic – High-Protein Diet and Kidney Health (2020)
Associates in Nephrology – Best and Worst Foods for Kidneys (2020)
Zhu H, et al. Biological Deciphering of the “Kidney Governing Bones” Theory in TCM. Evidence-Based Complementary and Alternative Medicine (2016)
Chinaculture.org, Tonifying the Kidneys in Winter (2011)