Cholesterol (HDL, LDL)

Cholesterol is a central protective molecule whose synthesis and circulation are powerfully regulated by the body, with its primary function being the production of defensive steroids like progesterone, DHEA, and pregnenolone. 2 Peat argued that the common designation of LDL as "bad" cholesterol is fundamentally mistaken, as LDL is the primary delivery system carrying cholesterol to the brain, ovaries, testicles, adrenal glands, and skin for steroidogenesis. 2 He maintained that cholesterol is protective against many kinds of poisoning, including heavy metals, and that a total cholesterol level around 160 to 220 mg% is generally reasonable, with low cholesterol (around 140 mg%) often indicating an inability to produce enough of these protective substances due to liver or intestinal damage. 2

The lipoproteins HDL and LDL are both defensive and anti-inflammatory, but they respond to different physiological demands. 2 LDL serves as the delivery system for cholesterol itself, while the protein component of HDL has more specific antitoxic effects, binding bacterial endotoxins and participating in detoxification. 2 Because HDL rises defensively against chemical irritants, Peat cautioned that a very high HDL is not necessarily a sign of good health; it can be driven up by estrogen, alcohol, radiation, chlorinated hydrocarbons, and even the peroxidation of fish oil. 3 He suggested that a ratio of roughly two or three parts LDL to one part HDL is usually reasonable, but emphasized that the interpretation is not simple. 6 Roddy has reiterated this framing, noting that while a high HDL indicates the body is mounting a defense, it is not a desirable state. 8

The size of the LDL particle is a critical factor in its atherogenicity, a nuance Peat highlighted as embarrassing for the medical establishment. 9 Smaller LDL particles have a greater surface area exposed to oxidative factors in the serum and are more rapidly degraded into toxic substances, whereas people with larger LDL particles are remarkably resistant to heart disease. 9 Dietary cholesterol and saturated fats, such as those from butter and eggs, have been shown to increase LDL particle size, generating a less atherogenic lipoprotein profile. 2 Peat cited studies where a high-cholesterol diet did not negatively influence the atherogenicity of LDL, and where the consumption of butter was associated with larger LDL particles compared to margarine. 2

Cholesterol levels are intimately tied to thyroid function. 2 Thyroid hormone increases the turnover of cholesterol and its conversion into protective steroids, making it a major factor in controlling inflammation. 4 In hypothyroidism, the pituitary secretes more TSH, which itself has pro-inflammatory actions, and cholesterol rises as a compensatory defense. 2 Roddy has described total cholesterol as "one of the best thyroid tests," noting that a very high cholesterol level obviously indicates extremely low thyroid function, while a sharp decline in total cholesterol follows the administration of thyroid hormone. 2 Conversely, when cholesterol is too low, it presents a more challenging situation requiring troubleshooting of why the liver is not making enough. 8 Peat observed that the rising cholesterol commonly seen with aging is probably only a partial compensation for declining thyroid function. 9