Diet Composition
Diet composition is an important concept in nutrition. It influences overall health, body weight, and risk of various diseases.
Micro vs Macronutrients
Macronutrients are those nutrients that the
body needs in large amounts, such as carbohydrates, protein, and fat.
Micronutrients are nutrients that the body needs in smaller amounts, such as vitamins and minerals.
Both macro and micronutrients are essential for good health.
Carbohydrates act as a major energy source for the body and can be simple or complex.
Simple carbohydrates are digested quickly and provide immediate energy. Refined sugar, fruit juices, and syrups are some of the commonly consumed simple carbohydrates, and their excess creates a surplus which could lead to a detrimental effect on health.
Complex carbohydrates contain longer chains of sugar molecules than simple sugars, are digested slowly and provide a steady and healthy source of energy. Common examples include grains, bananas, starchy vegetables (potato, sweet potato, breadfruit), and legumes (lentils, beans, etc).
Processed food is a type of food cooked, frozen, dried, baked, canned, or altered in various ways. Based on the processing, food will contain extra salt, sugar, oil, and calories.
Both simple and complex carbohydrate food sources can be refined and processed, and are widely available in the market. Many foods made via refined grains such as white rice and flour lack essential nutrients and vitamins. Whereas unrefined whole grains, fruits, and vegetables, on the other hand, are well balanced with vitamins and fibers, which provide a feeling of satiation and suitable for healthy nutrition.
Fats
Dietary fat is a rich energy source that is important for our cellular metabolism, keeps the body warm, and helps regulate hormones.
There are four types of dietary fat. Because each gram of fat can produce 9 calories, we should be mindful to eat dietary fat in moderation. Only 20-35% of total daily calories should come from fat.
Saturated fat is where carbon molecules are saturated with hydrogen molecules and are solid at room temperature.
It mostly occurs in animal products, dairy products, and some plants (coconut and palm). The American Heart Association recommends limiting saturated fat consumption including cheese, butter, and animal products, and replacing with mono or polyunsaturated fats. 
Monounsaturated fat has one unsaturated carbon molecule. It is typically liquid at room temperature and could become solid in cool temperature.
Monosaturated fats can provide nutrients, vitamins, and antioxidants while reducing bad cholesterol in the body. Foods that contain high in monosaturated fats include olive oil, canola oil, peanut oil and butter, avocados, and nuts and seeds. 
Polyunsaturated fat contains more than one unsaturated carbon molecule. It is also liquid at room temperature and solid at a cool temperature.
Foods that contain polyunsaturated fats include soybeans and soybean oil, corn oil, sunflower oil, walnuts, and tofu.
Some fish contain omega-3 and omega-6 fatty acids, which have many benefits on heart health and must be obtained through food as they are not produced in the body.
What is a trans-fat?
There are two types of trans fat, that available from animals and dairy products, and artificial product wherein extra hydrogen molecules are added to liquid vegetable oils to create a solid form.
Why should I avoid trans fats?
In many clinical studies, trans fats are associated with an increase in bad cholesterol, leading to the risk of coronary heart disease; therefore, it is highly recommended to minimize trans fats consumption. [2-4]
How to avoid trans fats?
Trans fat can be found in various foods and should be found on nutrition labels. It mostly occurs in frozen pizza, biscuits, crackers, and cookies and should be avoided at all costs.
Of these four types of fats, saturated fats and trans fats should be avoided or limited while replacing them with naturally occurring vegetable oils such as olive and canola oils.
Omega 3, 6, and 9 Fatty Acids
Dietary fat is a rich energy source that is important for our cellular metabolism, keeps the body warm, and helps regulate hormones.
There are four types of dietary fat. Because each gram of fat can produce 9 calories, we should be mindful to eat dietary fat in moderation. Only 20-35% of total daily calories should come from fat.
It belongs to polyunsaturated, essential fat and requires obtaining from your diet. Fish is an excellent dietary source to get fatty acids. Though there are multiple variants of omega-3 fats, the following are the most common category:
Eicosapentaenoic acid (EPA)/20-carbon fatty acid: Helps to reduce inflammation and mental health such as depression. [1,2]
Docosahexaenoic acid (DHA)/22-carbon fatty acid: Involves nervous system development and brain function. [3]
Alpha-Linolenic acid (ALA)/18-carbon fatty acid: It can be converted into EPA and DHA. Play an essential role in many physiological functions. Potential benefits of ALA include cardioprotective effects, modulation of the inflammatory response, and a positive impact on both central nervous system function and behavior. [4]
Foods that contain Omega-3 FA The American Heart Association recommends eating two servings of fish (particularly fatty fish) per week. A serving is 3.5 ounces cooked or about a cup of flaked fish. Common fish and seafood products rich in Omega-3 [5]
Seafood
Serving Size
Omega-3 FA (mg/serving)
Anchovy
2.0 oz
1,200
Catfish (farmed)
5.0 oz
253
Clams
3.0 oz
241
Cod (Atlantic)
6.3 oz
284
Crab
3.0 oz
351
Fish sticks (frozen)
3.2 oz
193
Halibut
5.6 oz
740
Lobster
3.0 oz
71
Mahi mahi
5.6 oz
221
Mussels
3.0 oz
665
Oysters
3.0 oz
585
Pollock (Alaskan)
2.1 oz
281
Salmon (wild)
6.0 oz
1,774
Salmon (farmed)
6.0 oz
4,504
Sardines
2.0 oz
556
Scallops
3.0 oz
310
Shrimp
3.0 oz
267
Swordfish
3.7 oz
868
Trout
2.2 oz
581
Tuna (albacore)
3.0 oz
733
Tuna (light, skipjack)
3.0 oz
228
Benefits of omega-3 fatty acids
⦁ Promote heart health
⦁ Reduce inflammation
⦁ Maintain healthy weight
⦁ Support brain health and development
⦁ Reduce liver fat
Omega-3 FA Research Several large trials have been done to evaluate the effect of fish oil on heart disease. In GISSI Prevention Trial, heart attack survivors who took a 1-gram capsule of omega-3 fats every day for three years were less likely to have a repeated heart attack, stroke, or sudden death than those who took a placebo. [6] In another study called JELIS, individuals who took EPA plus a statin were less likely to have major coronary events than those who took a statin alone. [7] A recent study reported a significant reduction of death from cardiac disease among those who received 2 g of icosapent ethyl twice daily than those who received placebo. [8]
- It is polyunsaturated fat and an essential nutrient as this fatty acid cannot be manufactured in our body.
- Found in nuts, seeds, and vegetable oils.
- The most common omega-6 fat is linoleic acid that can be converted to arachidonic acid.
Benefits of Omega-6
- Omega-6 fat has shown benefits in treating chronic disease.
- Gamma-linolenic acid (GLA) and dihomo-gamma-linolenic acid (DGLA) are members of Omega-6 fatty acids and may reduce inflammatory conditions. [9]
Sources of Omega-6
Safflower oil, Sunflower oil, Corn oil, Soybean oil, Sunflower seeds, Walnuts, Pumpkin seeds.
- It is a member of monounsaturated fats and can be produced in our body.
- The most common omega-9 fat is oleic acid that can commonly be found in diets.
Sources of Omega-9 fatty acids
Canola Oil, Sunflower Oil, Almonds, Nut Oil
Benefits of Omega-9 fatty acids
- Help to regulate blood cholesterol level (increase HDL and decrease LDL)
- Reduce the risk of cardiovascular disease and stroke
Role of Omega 3-6-9 supplements
Many omega supplements are available in the market. Omega 6 FA are essential up to a certain extent, but a regular diet can provide the daily requirement. Omega 9 can be produced in our body, and not need to take an extra supplement.
Taking only Omega 3 fatty acid supplements may help maintain a healthy heart as the latest scientific evidence reported that Icosapent ethyl, a highly purified eicosapentaenoic acid ethyl ester, had shown to reduce major cardiovascular events by 25%. [8]
Many omega supplements are available in the market. Omega 6 FA are essential up to a certain extent, but a regular diet can provide the daily requirement. Omega 9 can be produced in our body, and not need to take an extra supplement.
Taking only Omega 3 fatty acid supplements may help maintain a healthy heart as the latest scientific evidence reported that Icosapent ethyl, a highly purified eicosapentaenoic acid ethyl ester, had shown to reduce major cardiovascular events by 25%. [8]
Protein
What is a protein?
- Proteins are complex molecules which are made of chains of amino acids.
- They comprise an essential nutrient for cellular metabolism and growth as they act as a building block for the body and serve as an alternative fuel source.
- Protein can be found in both animal and plant food products. Meat, fish, dairy, and eggs are good sources that come from animals.
- Legumes (soybeans, lentils, kidney beans, white beans, mung beans, chickpeas, cowpeas, lima beans, pigeon peas, lupines, wing beans), nuts (almonds, Brazil nuts, cashews, pecans, walnuts), seeds are some plant-based options rich in protein.
- The National Academy of Medicine recommends that adults get a minimum of 0.8 grams of protein for every kilogram of body weight per day or just over 7 grams for every 20 pounds of body weight.
References
- Calder, Philip C. “Omega-3 fatty acids and inflammatory processes.” Nutrients vol. 2,3 (2010): 355-74. doi:10.3390/nu2030355
- Martins JG. EPA but not DHA appears to be responsible for the efficacy of omega-3 long chain polyunsaturated fatty acid supplementation in depression: evidence from a meta-analysis of randomized controlled trials. J Am Coll Nutr. 2009 Oct;28(5):525-42. doi: 10.1080/07315724.2009.10719785. PMID: 20439549.
- Innis SM. Dietary omega 3 fatty acids and the developing brain. Brain Res. 2008 Oct 27;1237:35-43. doi: 10.1016/j.brainres.2008.08.078. Epub 2008 Sep 9. PMID: 18789910.
- Stark AH, Crawford MA, Reifen R. Update on alpha-linolenic acid. Nutr Rev. 2008 Jun;66(6):326-32. doi: 10.1111/j.1753-4887.2008.00040.x. PMID: 18522621.
- Mozaffarian D, Rimm EB. Fish intake, contaminants, and human health: evaluating the risks and the benefits. JAMA. 2006 Oct 18;296(15):1885-99. doi: 10.1001/jama.296.15.1885. Erratum in: JAMA. 2007 Feb 14;297(6):590. PMID: 17047219.
- Dietary supplementation with n-3 polyunsaturated fatty acids and vitamin E after myocardial infarction: results of the GISSI-Prevenzione trial. Gruppo Italiano per lo Studio della Sopravvivenza nell’Infarto miocardico. Lancet. 1999; 354:447-55.
- Yokoyama M, Origasa H, Matsuzaki M, et al. Effects of eicosapentaenoic acid on major coronary events in hypercholesterolaemic patients (JELIS): a randomised open-label, blinded endpoint analysis. ⦁ Lancet. 2007; 369:1090-98.
- Bhatt, D. L., Steg, P. G., Miller, M., Brinton, E. A., Jacobson, T. A., Ketchum, S. B., … & Ballantyne, C. M. (2019). Cardiovascular risk reduction with icosapent ethyl for hypertriglyceridemia. New England Journal of Medicine, 380(1), 11-22.
- Sergeant, Susan et al. “Gamma-linolenic acid, Dihommo-gamma linolenic, Eicosanoids and Inflammatory Processes.” European journal of pharmacology vol. 785 (2016): 77-doi:10.1016/j.ejphar.2016.04.020