Introduction
Fats have long been considered an essential component of the dietary energy supply.
In the past, research on infants and children primarily focused on the total amount of fat they could tolerate and digest, paying little attention to the composition of dietary fat. However, there is now a growing interest in the quality of dietary lipid supply during early life, as it plays a crucial role in growth, infant development, and long-term health.
Selecting the right dietary fat and fatty acid sources in the first years of life is deemed critically important (Koletzko, 1997); (Uauy R. M.-D., 2000a).
Fats have certain advantages, including slow gastric emptying and intestinal motility, which helps prolong satiety, especially important for infants and children due to their small stomach size.
Additionally, dietary fats provide essential fatty acids (EFA) and facilitate the absorption of lipid-soluble vitamins. Being the primary energy source in the infant diet, fats are necessary for normal growth and physical activity. It's worth noting that fats typically contribute about half of the energy found in human milk and most artificial formulas.
Furthermore, fats represent the major energy store in the body, with the energy content of adipose tissue on a wet weight basis being 7 to 8 times higher than that of tissue containing glycogen or protein.
Exploring the Significance of Lipids and Fatty Acids in Neural Development and Lifelong Health
In recent decades, lipid nutrition has garnered significant interest, particularly regarding the role of essential lipids in central nervous system development and the influence of specific fatty acids and cholesterol on lipoprotein metabolism. Moreover, considerable attention has been given to the impact of fats and fatty acids on the development of nutrition-related chronic diseases (NRCD) throughout one's life.
Lipids serve as structural components in all tissues and play an indispensable role in assembling cell and cell organelle membranes. Among various tissues, the brain, retina, and neural tissues stand out for their richness in long-chain polyunsaturated fatty acids (LCPUFA). LCPUFA derived from n-6 and n-3 essential fatty acids (EFA) serve as precursors for eicosanoid production, which include important mediators like prostaglandins, prostacyclin’s, thromboxanes, leukotrienes, resolvins, and neuroprotectins.
These mediators act as powerful regulators of physiological functions, such as blood clotting, inflammatory responses, leukocyte migration, vasoconstriction and vasodilation, blood pressure, bronchial constriction, uterine contractility, when cells self-destruct, and preventing damage from oxygen when blood flow is restored.
Early dietary lipids have an impact on cholesterol metabolism and may be associated with cardiovascular morbidity and mortality later in life. Furthermore, lipid supply, particularly EFA and LCPUFA, influences neural development and function (Uauy & Hoffman, 1991) (Uauy R. M., 2000c). Specific fatty acids have been found to modify the physical properties of membranes, including membrane-related transport systems, ion channels, enzymatic activity, receptor function, and various signal transduction pathways.
Lately, scientists have found that certain fats can even change how our genes work, like switching them on or off, especially genes that control important things like how we use energy, how sensitive we are to insulin, how our body stores fat, and how our brain functions. All of this is really interesting and helps us understand how these important nutrients affect how our body works throughout our whole life. (Innis, 1991) (Lauritzen, 2001).
The Significance of Essential Fatty Acids for Human Growth and Development
George and Mildred Burr introduced the idea that certain fat components might be crucial for the growth and development of animals, including humans. They identified three specific fatty acids as essential: linoleic acid (LA n-6), arachidonic acid (AA n-6), and a-linolenic acid (ALA n-3).
Before the 1960s, essential fatty acids (EFA) were not considered very important for humans. However, in the 1960s, signs of EFA deficiency were observed in infants fed skimmed milk-based formulas and those receiving fat-free parenteral nutrition.
Research confirmed that LA is essential for normal infant nutrition. Deficiency in LA could cause dry and thickened skin, growth problems, and other clinical issues in young infants.
While babies can partially synthesize long-chain polyunsaturated fatty acids (LCPUFA) from their precursors, this process is limited. Studies suggest that in early life, the conversion of precursors to LCPUFA is insufficient for normal functioning, especially for docosahexaenoic acid (DHA).
Feeding infants with human milk has unique effects on EFA metabolism because it directly provides preformed LCPUFA, bypassing certain regulatory steps. Excessive dietary LA found in some vegetable oils can interfere with the formation of DHA from ALA, and EPA from marine oil may decrease the production of AA. The supply of LA and ALA in the diet is essential since humans cannot produce them.
DHA and AA can be synthesized from ALA and LA, respectively, but their conversion is limited. Because DHA and AA play critical roles in normal brain and retinal development, they are considered conditionally essential during early development. Additionally, they may be considered conditionally essential for lifelong health to prevent cardiovascular disease.
In summary, the research on essential fatty acids highlights their importance for human health, especially during early development and throughout life.
Recommended dietary intakes for total fat and fatty acid: infants (0-24 months) and children (2-18 years)
The following table is taken from the FAO (Food and Agricultural Organisation) report of an expert consultation ‘Fats and Fatty Acids in Human Nutrition’ 2010 (Food and Agricultural Organisation An expert consultation, 2008). This is the most up to date information in this important area.
Abbreviations
AMDR acceptable macronutrient distribution range
AI adequate intake (expressed as a range)
L-AMDR lower value of acceptable macronutrient distribution range
U-AMDR upper value of acceptable macronutrient distribution range
UL tolerable upper intake level
Conclusion
Fats have been recognized as essential components of the dietary energy supply, but recent research has shifted focus to the quality of dietary lipid supply during early life, crucial for growth, infant development, and long-term health. Specific fatty acids, such as linoleic acid (LA), arachidonic acid (AA), and a-linolenic acid (ALA), have been identified as essential for proper nutrition. The brain, retina, and neural tissues are rich in long-chain polyunsaturated fatty acids (LCPUFA), which serve as precursors for important physiological mediators like prostaglandins and leukotrienes, regulating various functions.
Lipid supply, particularly EFA and LCPUFA, influences neural development and function, and specific fatty acids play a role in modifying membrane properties, gene expression, and metabolic regulation. George and Mildred Burr's work highlighted the importance of these essential fatty acids for animal and human growth. Deficiency in LA was later confirmed as causing skin and growth issues in infants, leading to the recognition of its essential nature for normal nutrition.
While infants can synthesize LCPUFA from precursors, this conversion is limited, making preformed LCPUFA, like DHA and AA, supplied through human milk, vital for healthy development. Excessive dietary LA and n-6 fatty acids may hinder the formation of DHA, emphasizing the importance of omega-3 in the dietary fat profile. In conclusion, essential fatty acids play a critical role in human growth and development, and their proper intake is essential for lifelong health and well-being.
References
Food and Agricultural Organisation An expert consultation. (2008, November 10-14). Nutrition: Food and Agricultural Organisation. From Food and Agricultural Organisation of the United Nations: https://www.fao.org/nutrition/requirements/dietary-fats/en/
Innis, S. (1991). Essential fatty acids in growth and development. Prog. Lipid Res, 39-103.
Koletzko, B. T. (1997). Importance of dietary lipids. In Nutrition during infancy. Principles and Practice, 123-153.
Lauritzen, L. H. (2001). The essentiality of long chain n-3 fatty acids in relation to development and function of the brain and retina. Prog. Lipid Res, 1-94.
Uauy, R. M. (2000c). Essential fatty acids in early life: structural and functional role. Proc. Nutr. Soc., 3-15.
Uauy, R. M.-D. (2000a). Fat intake during childhood: metabolic responses and effects on growth. Am. J. Clin Nutr., 1354S-1360S.
Uauy, R., & Hoffman, D. (1991). Essential fatty acid requirements for normal eye and brain development. Semin. Perinatol, 449-455.
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