Lipids

Lipids included in Soylent

Algal and Canola Oil Oil Powder

Whole Algal Flour

Soy Lecithin

Types of Lipids included in Soylent 

Total Fat: 100.39 g

Saturated Fat: 10.14 g

Monounsaturated Fat: 68.73 g

Polyunsaturated Fat: 18.5 g (2.09 g Omega-3 Fatty Acids, 13.61 g Omega-6 Fatty Acids)

Trans Fat: 0.84 g

 

Introduction

In human nutrition, there are three primary categories of lipids: fats, phospholipids and steroids.

Fats

While plants use carbohydrates for energy storage, animals require fat, because carrying adequate energy reserves solely in carbohydrate form would make animals too large to move efficiently.[1] For comparison, fat provides nine calories per gram, while carbohydrates and protein provide just four calories per gram.[2]

On a fundamental level, a fat (also known as a triacylglycerol or triglyceride) is a glycerol molecule (C3H8O3) with three attached fatty acids. Each fatty acid is a chain of carbon atoms with attached hydrogen atoms (this also known as a hydrocarbon chain). In a concept similar to how carbohydrates deliver energy, most of the energy in fat comes from the electric charges of hydrogen atoms on hydrocarbon chains.[3]

Fats are divided into two primary types, unsaturated fats and saturated fats. The fatty acids on an unsaturated fat have at least one double bond between two carbon atoms in the chain, which prevents it from being completely "saturated" with hydrogens.[4] Importantly, this double bond causes a bend in the fatty acid chain.

Monounsaturated fatty acids, also known as "MUFAs", have a single double bond in the fatty acid chain. Polyunsaturated fats, commonly referred to as "PUFAs" have two or more double bonds.

Omega-3 fatty acids are polyunsaturated fatty acids whose first double bond occurs 3 bonds forward from the methyl group at the end of the fatty acid chain.[5][6] Of the most important types of omega-3 fatty acids are α-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).[7] While the body cannot synthesize omega-3 fatty acids, the the body can produce EPA and DHA from ALA.[8]

Omega-6 fatty acids, another type of polyunsaturated fat, cannot be produced by the body and must be consumed in the diet. Linoleic acid is an essential omega-6 and is used in the phospholipids of a cell's membrane.  

A saturated fat, in contrast to unsaturated fats, is composed of fatty acids that have their entire carbon chain "full" - or completely bonded with hydrogens. Saturated fat's full carbon chain prevents a double bond from forming between carbon atoms, which keeps the chain straight.

Straight chains of fat fit together more cleanly, which is why saturated fats are solid at room temperature and unsaturated fats (plant oils, for example) have the double bond and thus aren't able to easily fit together and remain liquid at room temperature.[9] Humans can generate adequate quantities of saturated fats and thus do not need additional saturated fats in the diet.[10]

Phospholipids

Without phospholipids, cell membranes wouldn't be able to regulate water intake or output. Unlike fats, phospholipids have only two fatty acids attached to the glycerol molecule. Instead of a third fatty acid, the third bonding site on the glycerol molecule is occupied by a phosphate group (PO43-).

Because the fatty acids are hydrophobic[11] and the phosphate group is hydrophilic[12], phospholipids naturally form a two-sided membrane, with the hydrophobic fatty acids pointing inwards and the hydrophilic phosphate groups facing outwards.

A diet containing excess amounts of saturated fats can cause lipid peroxidation, which can result in damage to cell membranes. The body uses several types of antioxidants[13] to stop or prevent lipid peroxidation, but insufficient amounts of antioxidants or excess amounts of free radicals (which can be increased by saturated fats), can overwhelm the antioxidants and damage tissue.[14]

Steroids

Historically sought-out by some professional athletes seeking an edge on their competition, anabolic steroids, are perhaps the best-known member of the steroid class of lipids.

The structure of steroids is vastly different than that of phospholipids and fats. Fundamentally, steroids are composed of three bonded hexagonal carbon rings and one attached pentagon-shaped carbon ring. The function of a given steroid depends on the group of molecules attached to the four-ring core as well as the rings' propensity to lose electrons (referred to as the "oxidation state").

Cholesterol, one of the body's most important steroids is required in the formation of many hormones. In total, the body converts approximately 50 mg of cholesterol to hormones each day.[15] However like saturated fat, the body can synthesize all of the needed quantity of cholesterol on its own and thus no dietary cholesterol is needed or recommended.

 

  


[1] Reece, Jane B., Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, and Robert B. Jackson. "The Structure and Function of Large Biological Molecules." In Campbell Biology, 76. Ninth Edition, Global ed. San Francisco, CA: Pearson, 2011.

[2] The FDA's method for the calculation of calories per gram for fat, carbohydrates and protein is outlined in this document.

[3] The double bond between carbons in unsaturated fat is a source of energy as well.

[4] Commonly discussed in the media, trans fats are a type of unsaturated fat that has an irregular bonding orientation. While found in some animal fats, trans fats are commonly the result of unsaturated fats being hydrogenated, which converts them to saturated fats while giving them a tran

[5] Nelson, David L., Michael M. Cox, and Albert L. Lehninger. "Lipids." In Lehninger Principles of Biochemistry, 358-359. New York: W.H. Freeman, 2013.

[6] In the greek alphabet, omega is the 24th and final letter.

[8] Nelson, David L. "Lipids." (see footnote 5)

[9] Reece, Jane B., Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, and Robert B. Jackson. "The Structure and Function of Large Biological Molecules." In Campbell Biology, 75. Ninth Edition, Global ed. San Francisco, CA: Pearson, 2011.

[10] http://plk.tn/1afGkl4 See "Dietary cholesterol" on page 6.

[11] Hydrophobic - repels water

[12] Hydrophilic - attracted to water

[13] Enzymatic antioxidants include catalase, superoxide dismutasse. Vitamin A and vitamin E function as non-enzymatic antioxidants.

[14] Mylonas C, Kouretas D. Lipid peroxidation and tissue damage. In Vivo. 1999 May-Jun;13(3):295-309. Review. PubMed PMID: 10459507.

[15] Erdman, John W., Ian MacDonald, and Steven H. Zeisel. "Lipids: Cellular Metabolism." In Present Knowledge in Nutrition, 135. Washington, DC: International Life Sciences Institute, 2012.