Marc Joseph Nutrition - Blog

Chronic inflammation is an important factor in many conditions, including heart disease, diabetes, cancer, neurodegenerative diseases (Alzheimer’s, Parkinson’s), arthritis, digestive disorders, and more.

In a recent study published in the top journal Science, researchers at the University of Chicago identified what seems to be a key link between the immune system and high blood lipid (cholesterol and triglyceride) levels.

Specifically, the scientists found that when tumor necrosis factor cytokines (immune system messengers) were over-expressed on T cells (white blood cells that regulate immune response and attack virus-infected, foreign, and cancer cells) in mice, that blood lipid levels rose.

Since the liver and intestines are believed to be primarily responsible for regulating blood lipid levels, the researchers also looked at the livers of the mice. The liver secretes an enzyme called hepatic lipase, which breaks down lipids (e.g., VLDL, triglycerides). The scientists observed that the livers of mice that had T cells expressing greater inflammatory cytokines produced less hepatic lipase, and thus had higher blood lipid levels.

As one of the study’s co-authors notes, the implications of this finding could be far-reaching:

“Those with inflammatory problems such as lupus, rheumatoid arthritis and inflammatory bowel syndrome have a higher incidence of cardiovascular disease, often associated with elevated lipid levels,” added co-author Godfrey Getz, MD, PhD, professor of pathology, biochemistry and molecular biology at the University of Chicago. “This study may explain why.”

Causes of Increased Inflammation

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The short answer: No. Shellfish is fine in moderation. The original research that estimated shellfish cholesterol levels used less sophisticated testing methods that weren’t able to distinguish between cholesterol and other sterols. As a result, cholesterol levels looked higher than they actually were.

Summary here.

Longer explanation here.

Here’s a table with the cholesterol content of various foods.

Among shellfish, shrimp, crab, and lobster tend to have the highest cholesterol levels.

Putting Things in Perspective

It’s important to note (and not well-known) that the average person’s body generates about 1000 mg of cholesterol per day from both external sources (diet) and internal sources (created by the body’s cells).

The average daily dietary cholesterol intake is ~600 mg, of which only about one-half is absorbed, or ~300 mg.

So, the typical diet only supplies less than one-third of your daily cholesterol. The rest is produced by cells in your body — about 20% by cells in your liver and the other 80% by other cells in the body. Statins work by inhibiting an enzyme that is involved in producing cholesterol in the liver.

Note that, using the table in the link above, you’d have to eat more than 3/4 lb. of shrimp or crab to take in 600 mg of cholesterol. I wouldn’t recommend eating that much regularly, but it helps to put things into perspective.

Bigger Concerns

I would be more concerned with potential toxins (heavy metals, PCBs) in seafood, as well as with antibiotics used in farm-raised species (e.g., shrimp). These levels, of course, vary depending on the type of seafood and from where it was sourced.

I would also be more concerned with overall intake of saturated fat and trans fat, both of which are positively correlated with greater risk of cardiovascular disease.

There are actually several different types of saturated fat. Some may promote higher bad cholesterol levels, while others may be neutral in their effect. Moderation is key.

Trans fats, on the other hand, are bad all around.

Cholesterol is an important chemical compound in the body. It’s used for hormones, bile salts, and even vitamin D. But there are several types (LDL, HDL, etc.), and ratios between the different types may be just as important as overall levels for predicting heart disease risk.

Cholesterol is often not the biggest problem in heart disease. Inflammation is. More on that here.

An interesting study in the American Journal of Medical Genetics found that abnormally low cholesterol levels were much more common in autistic children. 19 out of 100 autistic children studied had low cholesterol (< 100 mg/dl), a level lower than that found in 99 percent of children ages 4 through 19.

The researchers also found that the low cholesterol levels seemed to be the result of a reduced ability of the body to naturally make cholesterol (which occurs primarily in the liver), and not the result of low dietary cholesterol intake or a decreased ability to absorb it from the GI tract.

Cholesterol levels that are too low can be just as bad as high cholesterol levels, as cholesterol is used as a building block for:

• many hormones - e.g., sex hormones, cortisol
• bile acids - which the liver produces and helps with both the excretion of toxins and the absorption of fats
• and vitamin D - which is essential for proper immune system function

Perhaps not surprisingly, autistic individuals often have hormone and fatty acid imbalances, difficulty excreting toxins, and immune system irregularities.