High density lipoprotein

Introduction
Lipoproteins are complex particles composed of multiple proteins which transport all fat
molecules (lipid) around the body within the water outside cells
HDL particles remove fat molecules from cells. HDL particles are commonly mentioned
as “good cholesterol”, as they transport fat molecules out of artery walls. HDL is that the
smallest of the lipoprotein particles. It’s the densest because it contains the very best
proportion of protein to lipids. Cholesterol is an important structural component of the
cell wall, where it’s required to determine proper membrane permeability and fluidity.
additionally, cholesterol is a crucial component for the manufacture of bile acids, steroid
hormones, and Vitamin D. Although cholesterol is a crucial and necessary molecule, a
high level of serum cholesterol is an indicator for diseases like a heart condition. About
20–25% of total daily cholesterol production occurs within the liver.
Increasing concentrations of HDL particles are related to decreasing accumulation of
atherosclerosis within the walls of arteries, reducing the danger of sudden plaque
ruptures, disorder, stroke and other vascular diseases. HDL transports cholesterol
mostly to the organs like the adrenals, ovary, and testes by both direct and indirect
pathways. The cholesterol delivered to the liver is excreted into the bile and, hence, the
intestine either directly or indirectly after conversion into bile acids. Delivery of HDL
cholesterol to adrenals, ovaries, and testes is vital for the synthesis of steroid
hormones. HDL carries many lipid and protein species, several of which have very low
concentrations but are biologically very active. For instance, HDL and its protein and
lipid constituents help to inhibit oxidation, inflammation, activation of the endothelium,
coagulation and platelet aggregation.
While higher HDL levels are correlated with a lower risk of cardiovascular diseases.
Numerous lifestyle changes and medicines are under study to extend HDL levels.

Properties of HDL

  1. Reverse cholesterol transport
    Reverse cholesterol transport may be a pathway whereby excess cholesterol is
    transported from the peripheral tissues by HDL and bought to the liver for excretion
    within the sort of bile acids or reused.
  2. Antioxidant activity
    HDL has an antioxidant activity towards lipid-peroxides formed on LDL and within
    cell membranes.6 Several protein components of HDL contribute to the present activity.

HDL particles differ in their antioxidant activity counting on the distribution of those
antioxidant proteins, which aren’t equally distributed on all HDL particles.

  1. Anti-inflammatory activity
    the power of HDL to retard the oxidation of LDL, it can prevent the pro-inflammatory
    effects of oxidized-LDL on the endothelium. This retards monocyte –endothelium
    interaction, the primary stage within the inflammatory process in atherosclerosis.
    Although the antioxidant proteins of HDL contribute to those anti-inflammatory actions.
  2. Anti-apoptotic activity
    HDL can prevent LDL-induced apoptosis of endothelial and pancreatic b-cells. The
    precise mechanism is unclear, but it probably reflects the antioxidant activity of HDL,
    preventing LDL from activating the intracellular signalling mechanisms
  3. Reversing endothelial dysfunction
    LDL may be a powerful inducer of endothelial dysfunction causing changes to the
    vasodilatory properties of the artery wall. HDL reverses this effect by reversing the
    inhibition of gas (nitric oxide) synthase among other effects.13 This property of HDL
    appears to be mediated via the interaction of HDL-associated sphingosine-1-phosphate
    with specific receptors on the endothelial surface, which is additionally one among the
    mechanisms to scale back tumour necrosis

HDL and Cancer
An inverse correlation between HDL-C levels and cancer has been reported for various
sorts of tumours like breast cancer, lung cancer, liver cancer, prostate cancer and
colorectal cancers. Research suggesting that reduced plasma HDL-C levels were
causally linked with the danger of the development of different types of cancers within
the Asian population.

Certain changes in diet and exercise may have a positive impact on raising HDL
levels:
● Decreased intake of straightforward carbohydrates
● aerobic exercise

● weight loss
● avocado consumption
● magnesium supplements raise HDL
● Addition of soluble fibre to the diet
● Consumption of omega-3 fatty acids like animal oil
● Consumption of pistachio nuts
● Increased intake of unsaturated fats
● Consumption of medium-chain triglycerides
● Removal of fatty acids from the diet