The effect of stress on cholesterol levels is not clear. One of the problems is that stress is a vague term that is difficult to measure.

There has been a lot of research into the effects of stress on heart health in general, however. This has included looking at the indirect effects on cholesterol levels, such as how stress might affect lifestyle factors.

This article will look at exactly what stress means, and what cholesterol is. It will also cover some of the findings about the relationship between the two.

Contents of this article:

    What is stress?
    What is cholesterol?
    Stress and cholesterol
    Indirect effects of stress on cholesterol

What is stress?

Stress is a broad and often vague term. Every individual has their own response to things that cause stress known as stressors. What one person finds stressful, another person may see as exciting.

 Stress is understood by a variety of terms:

    Being under pressure
    Responding to difficult changes
    Losing control
    Feeling anxious, worried, or depressed
    Feeling threatened or vulnerable
    Responding to trauma or violence
    Anger and aggression
    Being distressed

 The body's reaction to stress is the flight-or-fight response. This is an automatic reaction.

When presented with a threat, the body automatically prepares the muscles, the heart, and other functions for a high-energy response. This response could be to run away or to tackle the threat.
How to control stress

Managing stress levels is a very individual matter. It will depend on the particular stressors put on the person, and how an individual tends to react to these. It will also depend on previous experience of stress.

Different people also find their own preferences for how to cope with different types of stress. Coping strategies range from positive self-talk and relaxation techniques to psychological counseling.
What is cholesterol?

Cholesterol is a fat-like, waxy-looking substance. Our bodies make cholesterol, but it is also taken in from food. Cholesterol is important for every cell of the body and has a number of functions. One of these is to make up the structure of cell walls.

Cholesterol is not carried around freely in the blood because it is water-repellent. Instead, it is carried in the blood by substances called lipoproteins. This is why cholesterol levels are measured by lipid levels.

There are two types of lipoproteins that carry cholesterol. Low-density lipoprotein (LDL) is known as "bad" cholesterol. High-density lipoprotein (HDL) is known as "good" cholesterol.
Recommended cholesterol levels

Healthy cholesterol levels are cited by the Centers for Disease Control and Prevention (CDC). It is recommended that adults have their cholesterol levels checked every 5 years with a blood test at the doctor's office.

Recommendations are to keep overall cholesterol levels low, and within this, keep the "bad" cholesterol portion down. Desirable cholesterol levels are (in milligrams per deciliter):

    Total cholesterol under 200
    LDL cholesterol under 100
    HDL cholesterol at least 60

Target cholesterol levels vary for each person.
Signs and symptoms of high cholesterol

Having high cholesterol levels does not produce any noticeable changes to the body itself.

Instead of showing any signs or symptoms, high cholesterol is diagnosed by blood tests and recorded as a risk factor.
How to control cholesterol

High cholesterol levels can be controlled by diet and exercise. They can also be prevented before they get too high.

A heart-healthy diet, as recommended by the American Heart Association (AHA) and many other groups, includes eating and drinking:

    Lots of different fruits and vegetables, and whole grains
    Dairy products that are low in fat
    Skinless poultry and fish
    Nuts and beans

Fat intake should be switched to non-tropical vegetable oils, while other fats are cut down.

This means the diet should be low in saturated fat, trans fat, salt, red meat, sweets and sugar-sweetened beverages.

What is good against cholesterol levels is also good against high blood pressure. A healthy diet has wide health benefits, including losing weight. Reducing obesity also tackles cholesterol.

 Being physically active also has wider benefits and helps to control cholesterol. The AHA recommend:

    150 minutes a week of aerobic activity of moderate intensity, or 75 minutes a week of vigorous exercise, for all adults
    To lower cholesterol levels, do around 40 minutes 3 to 4 times a week at a higher intensity

These are just guidelines, and any level of exercise is good. Physical activity can include brisk walking.

Doctors can also help to lower high cholesterol levels through drug treatments. Doctors may also recommend these if there are other heart risk factors or previous heart disease. A number of prescription options are available, including statins.

Stress and cholesterol

A number of studies have found that emotional stress increases cholesterol levels in the blood. Most of the findings relate to the immediate effects of stress.

One study, published in 2013, found a link between longer-term high cholesterol levels and work stress.

It concluded that the raised cholesterol was caused by job stress. So, instead of being due to stress effects on diet or exercise, the authors say the effect is a direct biological one.

The authors say chronic stress can raise long-term levels of the hormone cortisol. It can increase obesity around the stomach because of more fat deposits, has other fat effects in the body, and can even increase appetite.

Another study of 2,850 people also suggested a connection over the long term.

The authors propose that people with more severe anxiety disorders and depression may get raised lipid levels and obesity through a long-term inflammation effect. Smoking is also a factor, they add.
How the body reacts to stress

The body has a well-known immediate response to stress. When people are scared:

    The heart rate goes up, as does breathing
    Blood pressure rises

Anxiety also raises blood pressure.

Immediately following a challenging or threatening situation:

    The body releases the hormones epinephrine and norepinephrine
    This triggers the heart to work harder
    It leads to the release of glucose to the muscles and blood for use as energy
    Fatty acids are also released for energy use
    Cholesterol levels can rise because any free fatty acids not used for energy form lipids

Therefore, the body's short-term response to stress involves raised cholesterol.

One of the known short-term effects on cholesterol is called hemoconcentration. This means that fluid is lost from the blood under stress. This concentrates the blood, including its cholesterol levels. Simply standing up from sitting has this effect.

One study examining the stress spikes in cholesterol in this way found that the effect was not completely reversible. Some raised cholesterol level remained.

Another effect may be related to the hormone cortisol. This is released by the nervous system in response to a stressor. Lipid levels have been found to match up with this cortisol release.
Other heart effects of stress

Stress is already known to produce other effects. Some are dangerous. Mental stress-induced heart ischemia is a known condition in people who already have coronary heart disease (CHD).

This condition is when someone with CHD is at risk of a heart attack in response to mental stress due to a lack of blood supply to the area.

The stress-induced effect was confirmed in a study published in 2013 in the Journal of the American College of Cardiology.

The researchers took measurements of heart ischemia from 310 people with stable CHD. About half of the participants put under mental stress showed heart ischemia in response to a stressor.

 The authors of the research also discussed how sex, marriage, and living arrangements could influence heart problems. They call for more research into these factors.
The cardiovascular reactivity theory

Researchers have found that some people's blood pressure rises more than others in response to stress.

The cardiovascular reactivity hypothesis is the name for this, and it is a theory to suggest that stress can increase heart disease risks. Cholesterol has been implicated in causing an increased cardiovascular response to stress.

The effect is that people with high cholesterol levels have changes in the walls of their arteries. These make the arteries less elastic, so the blood vessels are less able to open up in response to stress.