Obesity is one of the major causes of several terminal diseases. Contrary to popular belief, not all fats are bad for human health. Fats are an essential part of the human diet. They are the source of fatty acids that perform various functions in the human body. These functions primarily include absorption of vitamins, energy storage for later use, and prostaglandin formation (lipids that help molecules communicate with each other). The chemical composition of fats comprises a three-carbon molecule called glycerol connected to the hydrocarbon chains at all three positions, collectively known as triglycerides. The nutrition chart of any food item generally categorizes fats as saturated, monounsaturated, and polyunsaturated. The fundamental difference among these types is the number of carbon-carbon double bonds present in the hydrocarbon chain attached to the glycerol molecule. The saturated fats have no carbon-carbon double bond present in their molecular structure, and therefore, they are closely packed and have a rigid structure at room temperature. The monounsaturated fats include only one pair of carbon-carbon double bonds present in the hydrocarbon chains, whereas the polyunsaturated fats contain two or more pairs of carbon-carbon double bonds present in their structure.
Schematic diagram of a triglyceride with a saturated fatty acid (top), a monounsaturated one (middle), and a polyunsaturated one (bottom).
Due to the presence of the double bonds in unsaturated fats, they have kinks creating gaps in the hydrocarbon chains by bending and making them less compact. As a result, unsaturated fats are usually liquid at room temperature. Humans can synthesize several fatty acids on their own, except for some polyunsaturated fatty acids known as essential fatty acids, which must be obtained from the diet. Most foods have a combination of all types of fats. Some have higher amounts of healthy fats than others. Let’s take a look at few examples of food sources that have higher concentrations of polyunsaturated fatty acids.
1. Walnuts
Walnut is one of the many food items that are known to have healthy polyunsaturated fatty acids in them. A walnut is the nut of any tree of the genus Juglans. In particular, the edible part of a walnut tree is the seed of a drupe (outer hard shelling), and thus it’s not a true botanical nut. There are several ways in which walnuts add flavor, crunch, and aroma to several dishes from main course appetizers to healthy desserts. Unlike many other nuts that are rich in monounsaturated fats, walnuts are mainly composed of polyunsaturated fatty acids (around 72%). In particular, walnut oil contains 58% linoleic acid and 14% alpha-linoleic acid, it also contains oleic acid (a monounsaturated fatty acid) as 13% of total fat content. Several analyses done on the health effects of walnuts show that diets enriched with walnuts led to lower total cholesterol and LDL (“bad”) cholesterol when compared with other diets. Many non-conclusive but supportive studies also show that eating 1.5 ounces (43 g) per day of walnuts, as part of a low saturated fat and low cholesterol diet and not resulting in increased caloric intake, may reduce the risk of coronary heart disease.
2. Flax Seeds or Flax Oil
Flax is one of the oldest crops, having been cultivated since the dawn of civilization. The earliest evidence of humans using wild flax to make textile goes back to 30,000 years ago. The Latin name of the flaxseed is Linum usitatissimum, which means “very useful.” Many of us are familiar with the variety of cloth called linen that is produced from this plant, which is why flaxseed is also known by the name linseed in the textile industry. In the last two decades, flaxseed has been the focus of increased interest in the field of diet and disease research due to the potential health benefits associated with some of its biologically active components. Flaxseeds have nutritional characteristics and are a rich source of ω-3 fatty acids including α-linolenic, short-chain polyunsaturated fatty acids (PUFA), soluble and insoluble fibers, phytoestrogenic lignans (secoisolariciresinol diglycoside-SDG), proteins, and an array of antioxidants. Flaxseed is one of the richest plant sources of the ω-3 fatty acid alpha-linolenic acid (ALA, C18:3 ω-3). The health benefits of introducing flax seeds to human diet include a reduction in the chances of cardiovascular diseases, decreased risk of cancer, particularly of the mammary and prostate gland, anti-inflammatory activity, laxative effect, and alleviation of menopausal symptoms and osteoporosis.
3. Chia Seeds
Chia seeds are the edible seeds of Salvia Hispanic, a flowering plant in the mint family (Lamiaceae). Among a diversity of plant foods with high nutritional interest, the chia seed has been highlighted for its chemical composition and potential nutritional value in the last decade. The chia seed contains important quantities of protein, minerals, fiber, polyphenols, and polyunsaturated fatty acids (PUFAs), and it is currently known as one of the best plant sources of omega-3 (n-3) fatty acid, α-linolenic acid (ALA). Nutritional analysis of chia seeds shows that they are also rich in carbohydrates. Therefore, several studies are going around the globe on how much chia seeds should be introduced into the human diet. Although preliminary research indicates that there are potential health benefits from consuming chia seeds, this work remains sparse and inconclusive. In 2009, the European Union approved chia seeds as a novel food, allowing bread manufacturers to add chia up to 5% in bread products. Chia seeds may be added to other foods as a topping or put into smoothies, breakfast cereals, energy bars, granola bars, yogurt, tortillas, and bread.
4. Seafood
Many aquatic animals, especially a variety of fishes, constitute a significant part of the human diet around the world. In fact, the livelihood of over 500 million people in several countries around the world depends directly upon aquafarming, contributing to the global GDP of around $300 billion USD per year. With the increasing awareness about obesity and the health effects of eating fats, the lean muscles of fish have become a quite popular alternative to beef and poultry, as it is much lower in calories and provides 18-25% of protein by weight. Fish oil is loaded with omega-3 fatty acids. These fatty acids must come from food since our bodies can’t make them. The two key omega-3 fatty acids are docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). The content of long-chain n-3 PUFAs is variable in seafood. Cold-water oily fish such as salmon, anchovies, herring, mackerel (Atlantic and Pacific), tuna (bluefin and albacore), and sardines have the highest levels of n-3 PUFAs. Seafood consumption is associated with improved neurologic development during pregnancy and early childhood, and it is more tenuously linked to reduced mortality from coronary heart disease. Omega-3 fatty acids play important roles in brain function, normal growth and development, and inflammation. Deficiencies have been linked to a variety of health problems including cardiovascular disease, some type of cancer, mood disorders, arthritis, and more. However, it doesn’t mean taking high doses will translate to better health and disease prevention. According to some studies, heavy intake of fish oil can lead to adverse effects on the health of older adults.
5. Safflower Oil
Cooking oil is one of the most necessary items in the kitchen. Healthwise, choosing the right oil for cooking is as necessary as the food itself. When you overheat cooking oil, it destroys beneficial compounds and creates harmful free radicals. Those free radicals can damage molecules in your body. That’s why it’s important to use oils with a high smoking point when you’re cooking at high temperatures. Safflower is a tall plant with spiked leaves and yellow or orange flowers. The flowers were used as a dye for clothing in ancient Egypt. Today, some people use safflower petals as a substitute for saffron, a yellow spice that’s often used to color and flavor rice dishes. Safflower seeds are used to produce safflower oil. Safflower kernels can be pressed into an oil with the highest concentration of polyunsaturated fats (75 to 82 percent) among all cooking oils. The concentration of polyunsaturated fats made safflower oil extremely popular in the 1970s when nutritionists touted the importance of polyunsaturated fatty acids. Two varieties of safflower oil are available: high-linoleic and high-oleic. High-linoleic safflower oil is rich in polyunsaturated fats, while high-oleic safflower oil contains more monounsaturated fats.
6. Soyabean Oil
Soyabean oil is one of the most common cooking oils present in the market, nowadays. It is made from pressing the oil from soybeans. Like many other seed oils, it’s high in unstable polyunsaturated fatty acids (PUFAs). In particular, per 100 g of soybean oil, there are 16 g of saturated fat, 23 g of monounsaturated fat, and 58 g of polyunsaturated fat. The major polyunsaturated fatty acids in soybean oil triglycerides are alpha-linolenic acid (C-18:3), 7-10%, and linoleic acid (C-18:2), 51%. The health aspects of using soyabean oil as cooking oil are full of mixed verdicts. While it is considered healthier than other cooking oils due to the presence of unhealthy saturated fats in lesser amounts, it is also known to be an oxidation-prone oil that produces free radicals when heated for a long time. It may not seem harmful, but chronic consumption of this oil might cause some severe health problems including liver diseases, heart diseases, immune toxicity, and diabetes.