Marketing Scoops: lipoproteins

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Struggling to manage your cholesterol through diet alone? Your snack cabinet, or more specifically, what’s missing from your snack cabinet, could be the key. A study found that eating pecans may lower cholesterol. According to the study, published in The American Journal of Clinical Nutrition, replacing some snacks with pecans may improve lipid/lipoproteins, which research shows helps reduce cholesterol numbers.

By Lauren Wellbank

Source: Prevention

Critics:

Animal fats are complex mixtures of triglycerides, with lesser amounts of both the phospholipids and cholesterol molecules from which all animal (and human) cell membranes are constructed. Since all animal cells manufacture cholesterol, all animal-based foods contain cholesterol in varying amounts. Major dietary sources of cholesterol include red meat, egg yolks and whole eggs, liver, kidney, giblets, fish oil, shellfish, and butter.

Human breast milk also contains significant quantities of cholesterol. Plant cells synthesize cholesterol as a precursor for other compounds, such as phytosterols and steroidal glycoalkaloids, with cholesterol remaining in plant foods only in minor amounts or absent. Some plant foods, such as avocado, flax seeds and peanuts, contain phytosterols, which compete with cholesterol for absorption in the intestines and reduce the absorption of both dietary and bile cholesterol.

A typical diet contributes on the order of 0.2 gram of phytosterols, which is not enough to have a significant impact on blocking cholesterol absorption. Phytosterols intake can be supplemented through the use of phytosterol-containing functional foods or dietary supplements that are recognized as having potential to reduce levels of LDL-cholesterol.According to the lipid hypothesis, elevated levels of cholesterol in the blood lead to atherosclerosis which may increase the risk of heart attack, stroke, and peripheral artery disease.

Since higher blood LDL – especially higher LDL concentrations and smaller LDL particle size – contributes to this process more than the cholesterol content of the HDL particles, LDL particles are often termed “bad cholesterol”. High concentrations of functional HDL, which can remove cholesterol from cells and atheromas, offer protection and are commonly referred to as “good cholesterol”. These balances are mostly genetically determined, but can be changed by body composition, medications, diet, and other factors.

A 2007 study demonstrated that blood total cholesterol levels have an exponential effect on cardiovascular and total mortality, with the association more pronounced in younger subjects. Because cardiovascular disease is relatively rare in the younger population, the impact of high cholesterol on health is larger in older people. The American Heart Association recommends testing cholesterol every 4–6 years for people aged 20 years or older.

A separate set of American Heart Association guidelines issued in 2013 indicates that people taking statin medications should have their cholesterol tested 4–12 weeks after their first dose and then every 3–12 months thereafter. For men ages 45 to 65 and women ages 55 to 65, a cholesterol test should occur every 1–2 years, and for seniors over age 65, an annual test should be performed.

A blood sample after 12-hours of fasting is taken by a healthcare professional from an arm vein to measure a lipid profile for a) total cholesterol, b) HDL cholesterol, c) LDL cholesterol, and d) triglycerides. Results may be expressed as “calculated”, indicating a calculation of total cholesterol, HDL, and triglycerides.

Cholesterol is tested to determine for “normal” or “desirable” levels if a person has a total cholesterol of 5.2 mmol/L or less (200 mg/dL), an HDL value of more than 1 mmol/L (40 mg/dL, “the higher, the better”), an LDL value of less than 2.6 mmol/L (100 mg/dL), and a triglycerides level of less than 1.7 mmol/L (150 mg/dL). Blood cholesterol in people with lifestyle, aging, or cardiovascular risk factors, such as diabetes mellitus, hypertension, family history of coronary artery disease, or angina, are evaluated at different levels.

Some cholesterol derivatives (among other simple cholesteric lipids) are known to generate the cholesteric liquid crystalline phase. The cholesteric phase is, in fact, a chiral nematic phase, and it changes colour when its temperature changes. This makes cholesterol derivatives useful for indicating temperature in liquid-crystal display thermometers and in temperature-sensitive paints.

Cholesterol has 256 stereoisomers that arise from its eight stereocenters, although only two of the stereoisomers have biochemical significance (nat-cholesterol and ent-cholesterol, for natural and enantiomer, respectively), and only one occurs naturally (nat-cholesterol).