Genes, women and ApoB

Why is my cholesterol high if I eat healthy?

By GyroscopeUpdated November 14, 20266 sources

Because your plate is only part of it. Your liver makes all the cholesterol your body needs, and your genes set how fast it clears LDL from your blood. FH, the inherited kind, affects 1 in 250 to 300 people. An underactive thyroid, menopause, keto and some medicines raise LDL too.

Why eating well isn’t always enough

People think of cholesterol as something you eat. But the CDC says blood cholesterol is “made by your liver,” and that your body makes all it needs. What you eat changes how much your liver makes and clears, and so do your genes.

The liver’s drain

Your liver pulls LDL out of your blood through LDL receptors on its cells. In FH, a change in one of the genes behind that system, most often the gene for the receptor itself, leaves the receptors working poorly, and LDL builds up from birth. It’s like a kitchen sink with a half-blocked drain. The tap runs at a normal rate and the water still rises.

FH affects 1 in 250 to 300 people, and up to 90% don’t know they have it. The guideline adds that up to half of children with a high LDL have no family history that anyone reports, so “nobody in my family has it” doesn’t rule it out.

Genes cut both ways

Some people are born lucky. In the US ARIC study, 2.6% of 3,363 Black participants carried a change in a gene called PCSK9 that lowered their LDL by 28% for life. Over 15 years, they had 88% less coronary heart disease. The same gene that can raise LDL in FH lowered it in them.

People also differ in how much food changes move their numbers. The guideline says the response to cutting saturated fat varies with how much bile you make and reabsorb and with your genes.

The healthy foods with saturated fat

The guideline names coconut oil alongside butter, red meat and high-fat milk as sources of saturated fat. A tablespoon of coconut oil has about 11 g, more than a tablespoon of butter at 7.3, and an ounce of cheddar has about 5. A keto diet heavy in meat and butter can push LDL up a lot in some people, the guideline says, sometimes into the range doctors check for FH.

The other causes

The guideline lists these causes of a high LDL, beyond food and genes:

• Health conditions: an underactive thyroid, kidney disease, liver disease that blocks the flow of bile, diabetes, Cushing syndrome and anorexia
• Weight: weight gain, and rapid weight loss
• Medicines: high-dose water pills, steroids, estrogens, androgens, some antipsychotics and cyclosporine
• Life stages: pregnancy and the menopause transition

Don’t stop a medicine on your own because of this list. Ask the person who prescribed it. The quiz Why is my cholesterol high? runs through these causes with your own answers and gives you a next step.