Nuts have a rich history of being one of the healthiest and tastiest foods available for human consumption. Numerous debates exist regarding their high calorie values and there are conflicting views on their effect on weight loss but beyond all such misconceptions nuts have surely sought a place for themselves in the ‘good’ food list for their valuable ‘good’ fat content (unsaturated fat). Though nuts mostly remind us of our very own cashew nut, almonds, pistachios and walnuts the latest favorites are the hazelnuts (HNs). I’m sure most of you would be familiar with this nut if not for the nut as a standalone food but as an important addition in Nutella alongside chocolate. There are many of those who were introduced to the healthy Hazelnut through the calorie-rich Nutella which is a chocolate-hazelnut spread. A study about cashews or almonds might be a repeat but there are many of those who are unaware of the goodness of this delicious ‘Hazelnut’.
Possible to Stay Unfazed by the Hazelnut?
Nuts have been boasted of numerous health benefits right from reducing the risk of cardiovascular disease (CVD) to improving HDL (good) cholesterol levels. Hazelnut containing healthy fats, vitamin E, proteins and dietary fibers exists as the second most popular nut worldwide only next to almonds. Also known as filberts from European folklore the top three producers of this nut include Turkey, Italy and the United States of America. Almost 80% of hazelnut is comprised of monounsaturated fat with less than 4% composed of saturated fat. Any food that contains fat in such proportions helps in reducing total blood and ‘LDL’ cholesterol levels. While this makes HN a healthy snack it is used very frequently while manufacturing foods such as chocolate spread, nougat, cookie, cereal bar, pastry and ice creams. Apart from this, HN is also used as a prominent cooking oil or consumed raw, roasted, chopped, powered or processed into a praline paste. All the nuts have their own individuality and health benefits but hazelnut plays an extremely prominent role in promoting human nutrition as it has a combination of nutrients-macronutrients (lipids, fiber), micronutrients (minerals, vitamins), fat-soluble bioactives and phytochemicals (flavonoids). Let us look at each of the nutrients closely:
Lipids & Fatty Acids
Lipids form a greater part of the nut providing the kernel flavor that’s quite evident after roasting. This nutrient constitutes more than 60% of the kernel’s dry weight and is composed of 98% triacylglycerols (TAG). Oleic acid is the most prominent fatty acid present (76-82%) in the nut followed by linolenic acid, palmitic, stearic and vaccenic acid. HN also contains high levels of polyunsaturated fatty acids (PUFAs) and monounsaturated fatty acids (MUFAs) that are helpful in eliminating the risk of coronary heart disease by mending blood lipid levels and blood pressure levels keeping away metabolic syndrome and insulin sensitivity.
Fiber is nothing but the roughage that’s resistant to small intestine digestion and requires microbiota fermentation that’s available in the large intestine. Almonds top the list (9%) in highest dietary fiber levels followed by HNs, walnuts, macadamia nuts and pistachios. A normal adult is recommended to eat 25 g/day of fiber for good health and for the prevention of problems such as colon cancer, heart disease and type 2 diabetes mellitus.
Minerals might be macro or micro minerals that include calcium, sodium, magnesium, potassium, chlorine, phosphorus and sulfur as macro minerals. Micro minerals include iodine, zinc, selenium, iron, manganese, copper, chromium, bromine and molybdenum. While each of the minerals are important for different functionality selenium is the most important of all as it is required for the production of a class of protein which helps with important functions such as skeletal and cardiac muscle function, T-cell immunity, thyroid hormone metabolism and antioxidant defense.
Tocopherols and tocotrienols are monophenols that are present in various nuts from macadamia to black walnut. HN oil contains high quantities of Vitamin E whose content depends on the geographic location of its growth. Peeling and roasting the nut also further removes tocopherol content to a greater extent. α- and γ-tocopherol are the most prevalent forms of isomers among which α-tocopherol contains high antioxidant activity. Vitamin E is also responsible for prevention of various diseases like cardiovascular, neurodegenerative, non-alcoholic fatty liver disease and certain kinds of cancer.
Phytosterols and Phytostanols
Plant sterols such as phytosterols and Phytostanols are eminently present in hazelnut. Phytosterols have the ability to reduce blood cholesterol levels by reducing low-density lipoprotein cholesterol (LDL-C) levels. These plant sterols do it by disabling cholesterol absorption at the intestinal level. The presence of phytosterols in diet decreases the chances of cancers such as colon, breast and prostate cancer.
We need nutrients such as minerals, vitamins and fibers for good health but the fruits and veggies that we eat contain plant secondary metabolites called as polyphenols that play a vital role in designing human health. Compared to the raw form, roasting the nut releases more phenolic content that are critical for protecting individuals against cancer.
Impact of Hazelnut Consumption on Blood Lipid Levels
In general, almonds, walnuts, pecans and peanuts have been shown to reduce total serum cholesterol levels (TC) and LDL levels. When researchers tried to find whether hazelnut also had such potential benefits their research was rewarded with equally beneficial effects. When all nuts could be tried and tested for their effect on heart health the reason why researchers went behind hazelnut was because of their high MUFA composition, intense presence of bioactive substances such as tocopherols and phytosterols, selenium, caffeic acid, fibers, gallic acid and p-hydroxy benzoic acid that have anti-atherogenic effect by means of biological mechanisms that act on various pathways in CVD development.
The study was conducted in accordance with PRISMA statement and the search included databases such as Medline and Google Scholar. Search criteria included various associated keywords, studies were eliminated based on various criteria and two authors reviewed each report independently. Weight, height, BMI, age and gender values were noted, the number of hazelnuts consumed per day, on the number of patients, on the number of supplementation days and on the type of control diet were all noted. Though the search came up with 779 papers only 385 of them were included for full-text review. After imposing selection criteria, the researchers were finally left with only 9 clinical trials for the study. A total of 425 individuals were involved of which 195 (46%) were males and 230 (54%) were females aged between 18 and 55 years. Of the 9 studies, 5 were randomized trials and the other 4 were non-randomized trials. Six studies had only healthy participants, 2 had hypercholesterolemic subjects and one study had subjects with type 2 diabetes.
Apart from systemic review a Bayesian random effect meta-analyses was performed. Results showed that of the nine studies, only 4 showed a significant decrease in mean total serum cholesterol levels (TC) and LDL cholesterol levels. Four studies saw a significant increase in HDL cholesterol levels, two studies found a significant decrease in TG and one study reported an increase in TG. Of the 8 studies with BMI data six studies showed no difference, one study showed a decrease in weight and one study showed an increase in BMI and body weight. The Bayesian meta-analysis reported that hazelnut consumption showed beneficial effects on serum cholesterol levels, including hazelnut in diet routine was definitely better at lowering serum LDL cholesterol levels and total cholesterol levels with no major difference in HDL cholesterol levels. Such distinct advantageous effect on serum cholesterol levels could be due to the lipid content of hazelnut. All these are favorable for a positive effect on cardiovascular disease (CVD) prevention.
Hazelnut as a Source of Micronutrient
Hazelnut, as we know from above, is a key source of micronutrient and a study now has confirmed its beneficial effects on older adults. Older adults lead a systematic lifestyle consuming certain foods that’s possible for them to chew, digest and eat in limited quantities. Nuts inclusion is not evidently present in this age group largely but this study might be an eye opener for all such adults to consume nuts- a variety of them for added health benefits. A study included 32 people aged 55 and above who ate around 57 grams of hazelnuts (1/3rd cup) daily for 16 weeks. Results showed increased levels of magnesium and vitamin E (breakdown product of alpha tocopherol). The blood samples also showed decreased glucose and LDL levels besides increase in magnesium and vitamin E levels-two of the most under-consumed micronutrients in the US where the study was conducted-and also being a healthy source of copper, healthy fats and vitamin B6. We are all very much bothered about macronutrient intake, especially fats and carbohydrates (the third one being proteins) intake but don’t give much priority to micronutrient consumption. Such decreased micronutrient intake can lead to several health problems especially in older people who are at an increased risk of age-related conditions such as Alzheimer’s disease. Many take multivitamins to compensate for lost nutrients but eating hazelnut might be a multivitamin of its own as it has a combination of many of the nutrients that humans desire for good health.
It’s good to know that hazelnut comes as a complete package with aplenty benefits but many individuals suffer from nut allergies and it is essential to ensure that you are not one of them! Also, when including nuts in dishes and shakes it is possible to overconsume them ignorant of the quantity. This can be dangerous as nuts are rich sources of calories and one must always be mindful of the quantity of nuts consumed anytime. Otherwise, it can lead to unnecessary weight gain.
Effects of Hazelnut Consumption on Blood Lipids & Body Weight: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5188407/
Hazelnuts as a Source of Bioactive Compounds & Health Value Underestimated Food: https://www.foodandnutritionjournal.org/volume7number1/hazelnuts-as-source-of-bioactive-compounds-and-a-health-value-underestimated-food/
Hazelnuts Improve Older Adults’ Micronutrient Levels, Study Shows: https://www.sciencedaily.com/releases/2018/12/181206135653.htm
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