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Published on: Jan 30, 2026
3 minute read
By: Secondmedic Expert

Health Risks Of Reusing Cooking Oil: How Reheated Oils Harm The Body

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Reusing cooking oil is a common household practice, especially in Indian kitchens where deep frying is frequent. While it may appear economical, repeated heating of oil leads to chemical changes that silently harm health. Understanding the health risks of reusing cooking oil is critical because these effects accumulate over time and contribute to chronic diseases.

What Happens When Cooking Oil Is Reheated

Cooking oil is stable only up to a certain temperature.

When oil is:

heated repeatedly
exposed to oxygen
used for deep frying

it undergoes oxidation, polymerisation and breakdown into harmful compounds.

Formation of Toxic Compounds

Repeated heating produces:

free radicals
aldehydes
trans fats
polar compounds

According to WHO and ICMR research, these substances are toxic to human cells and tissues.

Why Deep Frying Makes It Worse

Deep frying involves:

very high temperatures
long heating durations

This accelerates oil degradation, especially when the same oil is reused multiple times.

Street food and fast-food outlets often reuse oil extensively, increasing public health risk.

Impact on Heart Health

Oxidized oils:

damage blood vessel lining
increase LDL (bad cholesterol)
reduce HDL (good cholesterol)

Lancet studies link oxidized fats with atherosclerosis and increased heart disease risk.

Increased Risk of Inflammation

Toxic oil by-products trigger:

systemic inflammation
oxidative stress

Chronic inflammation is a known contributor to diabetes, heart disease and cancer.

Effect on Liver Function

The liver detoxifies harmful substances.

Reused oil increases liver burden, leading to:

fatty liver changes
enzyme elevation
impaired detoxification

ICMR reports show rising fatty liver disease linked to dietary habits.

Reused Oil and Cancer Risk

Some compounds formed during repeated heating are carcinogenic.

Studies associate long-term exposure to:

aldehydes
polycyclic aromatic hydrocarbons

with increased cancer risk.

Digestive Problems Caused by Reused Oil

Reheated oil irritates the digestive tract.

This can cause:

acidity
bloating
nausea
indigestion

Digestive symptoms are often early warning signs.

Why Certain Oils Are More Dangerous to Reuse

Oils high in polyunsaturated fats:

sunflower oil
soybean oil

break down faster under heat.

More stable options still degrade when reused.

No oil is safe for repeated reheating.

Effect on Blood Sugar and Metabolism

Oxidized fats:

worsen insulin resistance
impair glucose metabolism

This increases the risk of type 2 diabetes.

NFHS-5 data shows dietary fat quality significantly impacts metabolic health.

How Reused Oil Affects Children and Elderly

Vulnerable groups are more sensitive to toxins.

Children and elderly may experience:

digestive upset
immune stress
faster disease progression

Avoiding reused oil is especially important for these groups.

Common Signs Oil Should Be Discarded

Oil should never be reused if it:

smells rancid
becomes dark or sticky
smokes at low temperature
foams excessively

These signs indicate toxic breakdown.

Why Filtering Oil Does Not Make It Safe

Filtering removes food particles but does not remove:

oxidized fats
toxic aldehydes

Filtered oil remains chemically altered and unsafe.

Safer Cooking Practices

Healthier alternatives include:

shallow frying instead of deep frying
using fresh oil each time
controlling cooking temperature
switching to boiling, steaming or sautéing

Small changes significantly reduce risk.

Public Health Perspective in India

ICMR and NITI Aayog highlight:

increasing cardiovascular disease rates
rising metabolic disorders

Dietary fat quality is a major modifiable risk factor.

Reducing reused oil exposure is a key preventive step.

Role of Awareness and Prevention

Many people reuse oil unknowingly.

Awareness helps:

reduce toxin exposure
prevent chronic disease
protect long-term health

Preventive

Long-Term Health Consequences

Chronic exposure to reused oil contributes to:

heart disease
liver disorders
metabolic syndrome
increased cancer risk

These conditions develop silently over years.

Conclusion

The health risks of reusing cooking oil are serious and often underestimated. Repeated heating transforms oil into a toxic substance that damages the heart, liver, blood vessels and metabolism. While reusing oil may seem economical, the long-term health costs far outweigh short-term savings. Choosing fresh oil, avoiding deep frying and adopting safer cooking methods are simple yet powerful steps toward better health. Prevention begins in the kitchen.

References

World Health Organization (WHO) – Dietary Fats and Health Guidelines
Indian Council of Medical Research (ICMR) – Nutrition and Non-Communicable Diseases
National Family Health Survey (NFHS-5) – Dietary Patterns and Metabolic Risk
Lancet – Oxidized Fats and Cardiovascular Disease
NITI Aayog – Preventive Nutrition and Public Health Reports
Statista – Cooking Oil Consumption and Health Trends

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Read FAQs

A. Repeated heating breaks oil into toxic compounds that increase inflammation and disease risk.

A. Yes. Oxidized oils increase bad cholesterol and damage blood vessels.

A. Even limited reuse increases harmful by-products, especially at high temperatures.

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Difference Between Sadness and Depression: Understanding Normal Emotions vs Mental Illness

Feeling low or unhappy is a part of being human. However, not all low moods are the same. Many people confuse sadness with depression, which can delay proper support and treatment. Understanding the difference between sadness and depression is crucial for mental health awareness, early intervention and reducing stigma.

In India, mental health conditions are often misunderstood, with emotional distress frequently dismissed as temporary sadness.

What Is Sadness?

Sadness is a normal human emotion.

It usually occurs due to:

loss or disappointment
relationship issues
failure or stress
temporary life challenges

Sadness serves a psychological purpose, allowing individuals to process emotions and adapt.

Key Characteristics of Sadness

Sadness is:

situational
temporary
emotionally painful but manageable
responsive to support and positive events

A person experiencing sadness can still function, enjoy moments and feel hopeful.

What Is Depression?

Depression is a medical condition classified as a mood disorder.

It affects:

emotions
thinking patterns
behaviour
physical health

According to WHO, depression is one of the leading causes of disability worldwide.

Core Symptoms of Depression

Depression involves a combination of symptoms such as:

persistent low mood
loss of interest or pleasure
fatigue
sleep disturbances
appetite changes
feelings of worthlessness
difficulty concentrating

These symptoms last at least two weeks or longer.

Duration: A Key Difference

One major difference lies in duration.

Sadness:

lasts hours or days
improves with time

Depression:

lasts weeks or months
persists despite positive events

Duration helps distinguish emotional response from illness.

Impact on Daily Functioning

Sadness:

allows continuation of work and relationships
may reduce motivation temporarily

Depression:

interferes with work, studies and relationships
reduces self-care and productivity

Functional impairment is a defining feature of depression.

Emotional Experience: Sadness vs Depression

Sadness:

allows emotional range
moments of joy still occur

Depression:

creates emotional numbness
joy and interest disappear

People with depression often describe feeling empty rather than sad.

Physical Symptoms in Depression

Depression is not only emotional.

Physical symptoms include:

chronic fatigue
body aches
headaches
digestive issues

ICMR mental health studies highlight the physical burden of depression.

Thought Patterns and Self-Perception

Sadness:

thoughts remain realistic
self-worth is preserved

Depression:

negative self-talk dominates
feelings of guilt and worthlessness increase

These cognitive changes deepen emotional suffering.

Risk Factors for Depression

Factors increasing depression risk include:

chronic stress
trauma
family history
medical illnesses
hormonal changes

NFHS-5 data indicates rising mental health concerns among young adults.

Can Sadness Turn Into Depression?

Yes, prolonged or unresolved sadness can progress into depression.

This is more likely when:

stressors are ongoing
support systems are weak
coping mechanisms are limited

Early emotional support can prevent progression.

When to Seek Professional Help

Seek help if:

low mood lasts more than two weeks
daily functioning is affected
sleep and appetite are disturbed
thoughts of self-harm occur

Early care leads to better outcomes.

Treatment Differences

Sadness:

improves with rest, support and time

Depression:

requires psychotherapy
may need medication
benefits from structured care

WHO emphasises early treatment to reduce disability.

Role of Social Support

Support systems help both conditions but are essential for recovery.

Depression recovery improves with:

understanding family
supportive workplaces
accessible mental healthcare

Stigma reduction is key.

Mental Health Awareness in India

Mental health remains underdiagnosed in India.

NITI Aayog reports:

limited access to mental health services
low awareness
high stigma

Education helps bridge this gap.

Importance of Early Recognition

Recognising depression early:

prevents worsening
reduces suicide risk
improves quality of life

Delay increases suffering and complications.

Supporting Someone With Depression

Helpful actions include:

listening without judgement
encouraging professional help
avoiding minimising feelings

Compassion is more effective than advice.

Conclusion

Understanding the difference between sadness and depression is essential for emotional wellbeing and mental health care. Sadness is a natural, temporary response to life events, while depression is a serious medical condition that affects thoughts, emotions and daily functioning. Recognising the signs early and seeking appropriate help can prevent long-term suffering and promote recovery. Mental health deserves the same attention and care as physical health.

References

World Health Organization (WHO) – Depression and Mental Health Disorders
Indian Council of Medical Research (ICMR) – Mental Health Research and Burden
National Family Health Survey (NFHS-5) – Mental Health Indicators
Lancet – Depression, Disability and Public Health
NITI Aayog – National Mental Health Policy and Awareness Reports
Statista – Global and Indian Mental Health Trends

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