Nutrition

Question

This piglix contains articles or sub-piglix about Nutrition

Answer 1

Nutritional neuroscience

Nutritional neuroscience is the scientific discipline that studies the effects various components of the diet such as minerals, vitamins, protein, carbohydrates, fats, dietary supplements, synthetic hormones, and food additives have on neurochemistry, neurobiology, behavior, and cognition.

Recent research on nutritional mechanisms and their effect on the brain show they are involved in almost every facet of neurological functioning including alterations in neurogenesis, neurotrophic factors, neural pathways and neuroplasticity, throughout the life cycle.

Relatively speaking, the brain consumes an immense amount of energy in comparison to the rest of the body. The human brain is approximately 2% of the human body mass and uses 20-25% of the total energy expenditure. Therefore, mechanisms involved in the transfer of energy from foods to neurons are likely to be fundamental to the control of brain function. Insufficient intake of selected vitamins, or certain metabolic disorders, affect cognitive processes by disrupting the nutrient-dependent processes within the body that are associated with the management of energy in neurons, which can subsequently affect neurotransmission, synaptic plasticity, and cell survival.

Deficiency or excess of essential minerals (e.g. iron, zinc, copper, and magnesium) can disrupt brain development and neurophysiology to affect behavior. Furthermore, minerals have been implicated in the pathophysiology of neurodegenerative diseases including Alzheimer's dementia.

Iron is essential for several critical metabolic enzymes and a deficiency of this mineral can disrupt brain development. For, example chronic marginal iron affects dopamine metabolism and myelin fatty acid composition and behavior in mice. In rats a marginal iron deficiency that does not cause anemia disrupted axon growth in the auditory nerve affecting auditory brainstem latency without major changes in myelination. In rhesus macaques, prenatal iron deficiency disrupts emotional behavior and polymorphisms that reduce the expression of monoamine oxidase interact with gestational iron deficiency to exacerbate the response to a stressful situation leading to increased aggressiveness. Inexpensive and effective iron supplementation is an available preventative strategy recommended by the World Health Organization. However, iron supplementation can exacerbate malaria infection. Therefore, individuals receiving iron supplementation in malaria-endemic areas must be carefully monitored.

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Answer 2

Nutritional rating systems

Nutritional rating systems are methods of ranking or rating food products or food categories to communicate the nutritional value of food in a simplified manner to a target audience. Rating systems are developed by governments, nonprofit organizations, or private institutions and companies.

The methods may use point systems to rank or rate foods for general nutritional value or they may rate specific food attributes such as cholesterol content. Graphics or other symbols may be used to communicate the ratings to the target audience.

Nutritional rating systems differ from nutritional labeling in that they attempt to simplify food choices, rather than listing specific amounts of nutrients or ingredients. Dietary guidelines are similar to nutritional rating systems in that they attempt to simplify the communication of nutritional information, however, they do not rate individual food products.

Glycemic index is a ranking of how quickly food is metabolized into glucose when digested. It compares available carbohydrates gram for gram in individual foods, providing a numerical, evidence-based index of postprandial (post-meal) glycemia. The concept was invented by Dr. David J. Jenkins and colleagues in 1981 at the University of Toronto.

The glycemic load (GL) of food is a number that estimates how much the food will raise a person's blood glucose level after eating it.

Guiding Stars is patented food rating system that rates food based on nutrient density using a scientific algorithm. Foods are credited for vitamins, minerals, dietary fibre, whole grains, and Omega-3 fatty acids, and debited for saturated fats, trans fats, added sodium (salt) and added sugar. Rated foods are marked with tags indicating one, two or three stars. The program first launched a Hannaford Supermarkets in 2006, and is currently found in about 1,900 supermarkets in the US and Canada. Guiding Stars has also expanded into public schools, colleges and hospitals.

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Answer 3

Obesogen

Obesogens are foreign chemical compounds that disrupt normal development and balance of lipid metabolism, which in some cases, can lead to obesity. Obesogens may be functionally defined as chemicals that inappropriately alter lipid homeostasis and fat storage, change metabolic setpoints, disrupt energy balance or modify the regulation of appetite and satiety to promote fat accumulation and obesity.

There are many different proposed mechanisms through which obesogens can interfere with the body's adipose tissue biology. These mechanisms include alterations in the action of metabolic sensors; dysregulation of sex steroid synthesis, action or breakdown; changes in the central integration of energy balance including the regulation of appetite and satiety; and reprogramming of metabolic setpoints. Some of these proposed pathways include inappropriate modulation of nuclear receptor function which therefore allows the compounds to be classified as endocrine disrupting chemicals that act to mimic hormones in the body, altering the normal homeostasis maintained by the endocrine system.

Obesogens have been detected in the body both as a result of intentional administration of obesogenic chemicals in the form of pharmaceutical drugs such as diethylstilbestrol, selective serotonin reuptake inhibitor, and thiazolidinedione and as a result of unintentional exposure to environmental obesogens such as tributyltin, bisphenol A, diethylhexylphthalate, and perfluorooctanoate. Emerging evidence from laboratories around the world suggests that other chemicals will be confirmed as falling under this proposed classification in the near future, and that there may be some serious biological effects due to exposure to these chemicals that still remain undiscovered. Until now, 20 chemicals have been found responsible for inducing obesity within an individual.

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Answer 4

Nutritionism

Nutritionism is an alleged paradigm that assumes that it is the scientifically identified nutrients in foods that determine the value of individual food stuffs in the diet. In other words, it is the idea that the nutritional value of a food is the sum of all its individual nutrients, vitamins, and other components. Another aspect of the term is the implication that the only point of eating is to promote bodily health. The term is largely pejorative, implying that this way of viewing food is simplistic and harmful, and the term is usually used to label others' views. The concept's most prominent opponent, and popularizer of the term, journalist Michael Pollan, argues that a food's nutritional value is "more than the sum of its parts."

Originally credited to Gyorgy Scrinis, the notion was popularized by Michael Pollan. The key to Pollan's understanding of nutritionism is "the widely shared but unexamined assumption ... that the key to understanding food is indeed the nutrient." Since nutrients are invisible, it is now necessary to rely on nutrition experts to make food choices. Because science has an incomplete understanding of how food affects the human body, Pollan argues, relying solely on information regarding individual nutrients has led people and policy makers to repeatedly make poor decisions relating to nutrition. Pollan blames nutritionism for many of the health problems relating to diet in the Western World today. He compares Nutritionism to a religion, relying on "priests" (nutritional scientists and journalists) to interpret the latest orthodoxy for the masses. Like many religions, nutritionism has divided the world into good and evil components, although what is good or evil can change dramatically with time. Pollan believes that nutritionism is inherently flawed due to a reductive bias within science to isolate and study individual factors disconnected from their usual contexts such as diet and culture, factors which have repeatedly been shown to have a fundamental impact on nutritional outcomes. Even when scientists have attempted to study factors such as culture, diet, and long term consumption patterns, the enormous difficulties in making accurate measurements relating to individual nutritional components, and producing meaningful conclusions has resulted in incomplete results at best, and misleading or harmful results at worst.

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Answer 5

Obesity

Obesity

Obesity is a medical condition in which excess body fat has accumulated to the extent that it may have a negative effect on health. People are generally considered obese when their body mass index (BMI), a measurement obtained by dividing a person's weight by the square of the person's height, is over 7002294199500000000â™ 30 kg/m², with the range 7002245166250000000â™ 25–30 kg/m² defined as overweight. Some East Asian countries use lower values. Obesity increases the likelihood of various diseases, particularly heart disease, type 2 diabetes, obstructive sleep apnea, certain types of cancer, and osteoarthritis.

Obesity is most commonly caused by a combination of excessive food intake, lack of physical activity, and genetic susceptibility. A few cases are caused primarily by genes, endocrine disorders, medications, or mental illness. The view that obese people eat little yet gain weight due to a slow metabolism is not generally supported. On average, obese people have a greater energy expenditure than their thin counterparts due to the energy required to maintain an increased body mass.

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Answer 6

Oligosaccharide

An oligosaccharide (from the Greek olígos, "a few", and σάκχαρ sácchar, "sugar") is a saccharide polymer containing a small number (typically two to ten) of simple sugars (monosaccharides). Oligosaccharides can have many functions including cell recognition and cell binding. For example, glycolipids have an important role in the immune response.

In general, they are found either N- or O-linked to compatible amino acid side-chains in proteins or to lipid moieties (see glycans). N-linked oligosaccharides are found attached to asparagine via a beta linkage to the amine nitrogen of the side chain. Alternately, O-linked oligosaccharides are generally attached to threonine or serine on the alcohol group of the side chain.

In biology, glycosylation is the co-translational process by which a carbohydrate is covalently attached to an organic molecule – creating structures such as glycoproteins and glycolipids.

N-linked glycosylation involves oligosaccharide attachment to asparagine via a beta linkage to the amine nitrogen of the side chain. The process of N-linked glycosylation occurs cotranslationally, or concurrently while the proteins is being translated. Since it is added cotranslationally, it is believed that N-linked glycosylation helps determine the folding of polypeptides due to the hydrophilic nature of sugars. All N-linked Oligosaccharides are composed of a core of five sugars - known as a pentasaccharide.

In N-glycosylation for eukaryotes, the oligosaccharide substrate is assembled right at the membrane of the ER. For prokaryotes, this process occurs at the plasma membrane. In both cases, the acceptor substrate is an asparagine residue.They are small carbohydrates which are formed by condensation of 2-9 monosacchrides. This asparagine has increased nucleophilicity in the amide group. The unique arrangement of N-linked oligosaccharides usually has the oligosaccharide linked to the amide nitrogen of the Asn residue, in the sequence Asn-X-Ser/Thr. X can be any amino acid except for proline (though it is rare to see Asp, Glu, Leu, or Trp).

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Answer 7

Organic feeding disorders

Organic feeding disorders are created when there are changes in an organism which directly or indirectly affect the organism's need to survive, or the need for nourishment. For example, when someone becomes ill, their body is naturally not as hungry as it was before. This can also occur if a person's food intake is reduced; over time they will not want to eat as much and will reduce their efforts towards seeking out nourishment.

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Answer 8

Overall Nutritional Quality Index

The Overall Nutritional Quality Index is a nutritional rating system developed at the Yale-Griffin Prevention Research Center. It assigns foods a score between 1 and 100 to reflect the overall nutrition provided relative to the calories consumed. The system has been marketed commercially as NuVal, and some consumer foods in the United States are marked with ONQI values as "NuVal".

The ONQI for a food is the ratio of a "numerator" value representing beneficial nutrients such as iron, dietary fibre and vitamins, and a "denominator" value representing detrimental nutrients such as cholesterol and saturated fat.

The following foods have the maximum ONQI of 100:broccoli, blueberries, okra, oranges and green beans. Some of the lowest ONQIs are for white bread (9), hot dog (5), apple pie (2) and popsicle (1).

Here is a selection of food rankings from Yale University's Overall Nutritional Quality Index (scores out of 100)

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Answer 9

Overnutrition

Overnutrition or hyperalimentation is a form of malnutrition in which the intake of nutrients is oversupplied. The amount of nutrients exceeds the amount required for normal growth, development, and metabolism.

The term can also refer to:

For mineral excess, see:

Overnutrition may also refers to greater food consumption than appropriate, as well as other feeding procedures such as parenteral nutrition.

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Answer 10

Oxygen radical absorbance capacity

Oxygen radical absorbance capacity (ORAC) is a method of measuring antioxidant capacities in biological samples in vitro.

A wide variety of foods have been tested using this method, with certain spices, berries and legumes rated highly in extensive tables once published by the United States Department of Agriculture (USDA), but withdrawn in 2012 since no correlation between test results and biological activity could be determined, stating that no physiological proof in vivo existed in support of the free-radical theory.

Although not all have been unilaterally dismissive, the majority position supports the USDA decision. Alternative measurements include the Folin-Ciocalteu reagent, and the Trolox equivalent antioxidant capacity assay.

The assay measures the oxidative degradation of the fluorescent molecule (either beta-phycoerythrin or fluorescein) after being mixed with free radical generators such as azo-initiator compounds. Azo-initiators are considered to produce the peroxyl radical by heating, which damages the fluorescent molecule, resulting in the loss of fluorescence. Antioxidants are considered to protect the fluorescent molecule from the oxidative degeneration. The degree of protection is quantified using a fluorometer. Fluorescein is currently used most as a fluorescent probe. Equipment that can automatically measure and calculate the capacity is commercially available (Biotek, Roche Diagnostics).

The fluorescent intensity decreases as the oxidative degeneration proceeds, and this intensity is typically recorded for 35 minutes after the addition of the azo-initiator (free radical generator). So far, AAPH (2,2’-azobis(2-amidino-propane) dihydrochloride) is the sole free-radical generator used. The degeneration (or decomposition) of fluorescein is measured as the presence of the antioxidant slows the fluorescence decay. Decay curves (fluorescence intensity vs. time) are recorded and the area between the two decay curves (with or without antioxidant) is calculated. Subsequently, the degree of antioxidant-mediated protection is quantified using the antioxidant trolox (a vitamin E analogue) as a standard. Different concentrations of trolox are used to make a standard curve, and test samples are compared to this. Results for test samples (foods) have been published as "trolox equivalents" or TEs.

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