Does a low-carb diet increase LDL Cholesterol?

Does a low-carb diet increase LDL Cholesterol?

8 Facts about Low Carb & LDL-C

Author: Deborah Ng SJ

Understanding LDL Cholesterol

Before we go into this question, let us first understand what LDL is. Basically, our Total Cholesterol is formed by: HDL + LDL + 20% Triglycerides = Total Cholesterol score

Cholesterol is a soft, fat-like substance found in all the body's cells and the bloodstream. LDL is a low-density lipoprotein, often known as the "bad" cholesterol. It is often believed that LDL can accumulate in the inner walls of your arteries when it combines with other chemicals, including fats. If this happens, the arteries will become narrow and clogged, resulting in less blood flow (9).

On the other hand, the "good" cholesterol known as high-density lipoprotein (HDL) helps prevent heart attacks and strokes by removing dangerous cholesterol from the arteries.

However, knowing that cholesterol is vital in our body is important.

Our cells synthesize cholesterol, and each cell produces its own cholesterol. Cholesterol is a critical component of cell membranes, similar to a house in a community (your body).

The bile acids we use to digest food are also synthesized from cholesterol in the liver. Without sufficient bile acids, we won't be able to digest most food, especially food that contains high fat. Hence, we can't effectively absorb fat-soluble vitamins, and even the flora in the intestines will be affected.

So, should we be afraid of high LDL, and have you ever wondered why your LDL levels seem to spike when you switch to a low-carb diet? In this blog, we will unravel the mysteries surrounding LDL:

Is there a link between high LDL and body weight?
Can lowering LDL really prevent heart disease?
Why do people experience increased LDL when losing weight?
The lower the LDL, the better?
What should you be concerned with a high LDL?
LDL’s correlation with mortality/death rates?
Why does LDL increase on a low-carb diet?

1. Does weight affect LDL-C?

A high LDL cholesterol level is believed to cause the walls of the arteries to build up, form plaques, and lead to heart disease. Therefore, it is easy to hypothesize that a high level of LDL will be strongly associated with weight gain.

However, studies show the contrary. People on a low-carb diet had lower BMI scores but higher LDL; in contrast, people with higher BMI had lower levels of LDL.

The study carefully selected 1,379 participants (1) who followed a low-carb diet (less than 130g of carbs daily) for 19.4 weeks. It examined how this diet affected their body mass index (BMI) and LDL cholesterol levels.

This study found that low-carb diets raise LDL cholesterol in lean individuals but not in overweight or obese individuals. Furthermore, saturated fat intake does not affect the LDL changes.

Results revealed that adults who consumed a low-carb diet did increase their LDL levels by 41mg/dL but weighed below BMI <25; in other words, a healthy BMI level.

Surprisingly, individuals with higher BMI (obese and above >35) experienced a decrease of 7mg/dL of LDL. However, there were no significant changes in LDL levels for those with BMIs between 25 and 35 (overweight).

2. Does lowering LDL prevent heart disease?

Before discussing LDL, let's evaluate TC (Total Cholesterol) first.

If high total cholesterol (TC) was the leading cause of cardiovascular disease (CVD), people with high TC should have a higher risk of death rates from CVD.

However, a follow-up study after 30 years of findings found that for each 1mg/dl decrease in TC per year, resulting in an 11% increase in death from coronary and heart diseases (CHD) (2).

An Austrian study of over 67,000 men and 82,000 women found weekly links to CHD in men, except middle-aged men between 50 and 64, and no links between TC and CHD for women of all ages (3). Hence, the focus was directed to LDL instead.

Can you still have clogged arteries with low cholesterol?

Does lowering LDL prevent heart disease?

The answer is yes from a study with nearly 140,000 patients who were admitted to the hospital due to a heart attack had lower than normal levels of LDL (4).

In another study that intentionally lowered the patients’ LDL even more (5), death rates were shockingly (x2) twice as high for people who had an LDL level below 105mg/dL (<2.72 mmol/L).

3. Losing weight causes high LDL?

The above research shows that most individuals consuming low-carb diets have reported increased LDL levels. What is the reason for this?

When we shed fat, our fat stores decrease during weight loss. When these fat cells shrink, the fat and cholesterol that are typically stored in fat tissue and liver cells have no place to go. As a result, they enter the bloodstream, causing a temporary rise in cholesterol levels. This is a normal part of the weight loss process and should not be a cause for concern.

Weight loss can also alter hormone levels, such as thyroid hormones and cortisol, which can influence cholesterol metabolism; especially for those people with insulin resistance or metabolic syndrome, an increase in LDL indicates the body is adjusting its metabolism.

It is important to note that Cholesterol levels do not drop relative to a drop in fat-weight pound by pound. Therefore, these levels will likely decrease once the body stabilizes during weight loss. It might take up to six months, even a year, to see a lower LDL level after a successful diet and weight loss experience, notably slower for women than men (6).

So, what is a better predictor for cardiovascular disease? Research revealed that people with the highest triglyceride (bad fat in blood)/HDL (good cholesterol) ratio have a staggering x16 risk of heart attack than those with the lowest ratio of triglyceride to HDL.

The study found that higher triglyceride levels, lower HDL-cholesterol levels, and higher ratios of triglycerides to HDL-cholesterol were linked to more severe coronary artery disease. However, there was no significant link between total cholesterol or LDL-cholesterol levels and the severity of coronary artery disease (7).

TG/HDL ratio is also a good predictor for insulin resistance. A ratio of <1 is perfect, <2 is fine, and if your ratio is above 3.7, you are at increased risk for diabetes or pre-diabetes.

Here is an example: If your triglyceride level is 150mg/dL (1.7 mmol/L) and your HDL level is 50mg/dL (1.3 mmol/L), then your ratio is 75/25 = 3 (high risk).

4. What happens if LDL is too low?

Many of us are afraid of elevating LDL, but did you know that LDL function is essential in our body? Having a very low level of LDL poses several risks. Let's look at it:

Hormonal Imbalances: LDL cholesterol is a precursor for synthesizing steroid hormones, including cortisol, testosterone, and estrogen. Very low LDL levels can disrupt these hormones' production, leading to imbalances.

Nutritional Deficiencies: LDL helps transport fat-soluble vitamins (A, D, E, and K) throughout the body. Extremely low LDL levels impair the absorption and distribution of these essential vitamins, leading to deficiencies.

Cognitive Function: Cholesterol is crucial for maintaining the structure and function of cell membranes, particularly in the brain. Very low cholesterol levels have been linked to an increased risk of neurocognitive issues, including depression and anxiety.

Increased Risk of Infections: LDL cholesterol plays a role in the immune system by binding and neutralizing bacterial toxins. Very low LDL levels increase the risk of infections.

Hemorrhagic Stroke: Also known as the bleeding in the brain, this type of stroke is less common than ischemic stroke but can be more severe. A 9-year follow-up study with over 96,000 participants found that individuals with LDL levels below 70 mg/dL had a higher risk of hemorrhagic stroke (8).

5. Should I be concerned with high LDL?

We know that LDL is not that harmful, and it is essential for cell development and healing now. So, should you be afraid of a high level of LDL, and what should you do further to evaluate whether your LDL is putting you at risk?

You can tell your doctor to measure your small LDL particles B and sdLDL (Small, Dense LDL). Most people don't know that there are, in fact, 2 types of LDL patterns:

LDL particles A: This is covered with a layer of fat, protecting us from oxidation. Nearly 80% of this large, buoyant LDL is in our total LDL. Hence, this explains why people who consume a low-diet diet lose weight and experience an increased LDL.

This kind of particle A moves effortlessly in water. It flows in our bloodstream, where our body carries and transports cholesterol and triglycerides for cellular repair and other essential functions. It is also more resistant to oxidation, which reduces its ability to cause inflammation and damage in the arteries.

LDL particles B: The remaining 20% of LDL is particles B, which you should be really concerned about. These small, dense particles of LDL are dangerous as they oxidize very quickly.

Higher risk is often associated when particle B is oxidized or destroyed by inflammation; this is when LDL is trapped and stored within the blood vessels, causing the atherosclerosis process (the buildup of plaque in arteries, leading to reduced blood flow).

The pattern B LDL particles stay in circulation longer, are easily oxidized by free radicals and can penetrate the arterial walls easily.

So, how do you test your LDL particle B? A good indicator will be the apolipoprotein APOB test.

ApoA1: This is the main protein component of high-density lipoprotein (HDL), often referred to as "good cholesterol."

ApoB: This is the main protein component of low-density lipoprotein (LDL) and very low-density lipoprotein (VLDL).

ApoB/ApoA1 Ratio: A lower ApoB/ApoA1 ratio indicates a lower risk of cardiovascular disease because it suggests a higher proportion of protective HDL relative to harmful LDL.

It is advisable to get at least a ratio below 0.7 to indicate a lower risk of cardiovascular disease; the lower, the better.

In addition, Nuclear Magnetic Resonance (NMR) Spectroscopy is recommended to measure sdLDL levels. It can differentiate between different lipoprotein particles based on their size and density and provides a detailed profile of LDL particle size and concentration.

6. LDL's correlation with mortality/death rates

We understand that "bad cholesterol" isn't really bad now. To support this hypothesis, it is also important to investigate the association between LDL levels and mortality rates.

A 6-year follow-up study of over 177,000 adults aged 50 to 89 without diabetes and not on statin therapy found a U-shaped relationship between LDL-C levels and mortality rates. Against the given guidelines, patients with lower levels of LDL had a higher mortality rate, while individuals with higher levels of LDL had the lowest mortality rate.

Here is the breakdown (10):

LDL levels between 30-79mg /dL - 23% higher risk of mortality.

100-129 mg/dL - 13%

130-159 mg/dL - 12%

160-189 mg/dL - 9% (Lowest risk)

Above ≥190 mg/dL (4.9 mmol/L) - 19%, even lower than people with the lowest LDL levels.

Similar research focusing on the elderly (over 68,000 participants above >60 years old) found that those with higher levels of LDL-C did indeed live even longer than those with statin treatments (11). Hence, LDL-C alone was not the primary cause of atherosclerosis and CVD.

7. Key Characteristics of Lean Mass Hyper Responders

Why does LDL increase on a low-carb diet?

There is a term for this group of individuals called the "Lean Mass Hyper Responder" (LMHR); it refers to individuals who experience significant increases in their cholesterol levels, mainly low-density lipoprotein cholesterol (LDL-C) when following a low-carbohydrate, high-fat (LCHF) diet, such as the ketogenic diet.

It's important to note that despite these elevated cholesterol levels, LMHR individuals tend to be lean and have a host of other favorable health markers, including:

Lean Mass Hyper Responders characteristics

Elevated LDL-C: Significant increase in LDL cholesterol levels after adopting a low-carb, high-fat diet. The average LDL-C can rise to 148mg/dL to as high as 320 mg/dL for LMHR (12).

Low Triglycerides: Despite the rise of LDL, triglyceride levels in LMHR remain low (mean TG of 47 mg/dL), often associated with improved metabolic health.

High HDL-C: High levels of high-density lipoprotein cholesterol (HDL-C) are often considered protective against heart disease. The average HDL-C of LMHR can increase to 99 mg/dL.

Decreased BMI: The changes in LDL-C and HDL-C are more pronounced in individuals with lower Body Mass Index (BMI). The lower the BMI, the greater the increase in both types of cholesterol.

Lean Body Mass: They generally have a low body fat percentage and a lean physique because the body shifts to relying more on fat for energy, called the lipid energy model (LEM).

The mechanism of LEM occurs when the body uses more fat for energy; the liver produces more VLDL particles, which are broken down into LDL-C, resulting in elevated LDL-C and HDL-C levels and lower TG levels. Hence, LMHR often reported feeling more energized and able to engage in regular, intense physical exercise as their body condition improved.

8. Key Takeaways:

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