Research Diet Inc. An Incredible Source of High-Fat Diets for Research Models
The significance of dietary choices is sometimes overlooked when designing experiments using animal models, especially if diet is not the primary focus of the study. This is evident in the methods sections of many articles in experimental animal science, where readers frequently read ambiguous words like "standard chow" or "normal food" that offer no meaningful context. There are numerous reasons to carefully analyse the diet for every experiment, particularly in light of the fact that dietary factors are known to affect almost every phenotype, from health to disease traits.Standard chow is also known as a cereal-based diet, or "chow," that is made up of ingredients including soybean meal, ground corn, fish meal, and animal byproducts. With very few exceptions, these formulations are "closed," which means that the proportions of each ingredient used are secret and not disclosed to the research community. Additionally, depending on the nutrient levels in those specific batches of ingredients, some manufacturers will change the amount of an ingredient in the chow from one batch to the next.The chow typically contains very high levels of both soluble and insoluble fibre, often making up about 30% of the chow and coming from several sources. Additionally, chows frequently contain significant amounts of harmful heavy metals like arsenic as well as non-nutritive but biologically active substances like phytoestrogens. It is impossible to maintain constant nutritional and non-nutrient profiles between batches or between experiments employing chows because changes in the content of components from one batch to the next may occur.
Contrary to chows, purified diets use refined ingredients, and their recipes are "open" to researchers so they can determine the proportions of each item. Purified diets' refined components give full control over their nutrient contents. The researcher can easily report the diet's formula and nutritional content, reproduce the composition from batch to batch, and modify the diet as needed thanks to the utilisation of substances like casein (mostly protein), maize starch (carbohydrate), soybean oil (fat), and cellulose. As such, purified diet compositions can be customised to each researcher's needs. The fibre supply in chow diets is derived from many grain sources; manufacturers cannot selectively remove or change particular dietary components like this in pure diets. Since the 1920s, purified diets have been employed, and they were significant in revealing the important nutritional functions of vitamins and minerals. (Figure 1)
In 1976, a committee of nutrition researchers assembled to develop an open, fixed formula for a diet with purified ingredients and low in fat, that could be fed to mice and rats at all life stages. This diet formula, known as the AIN-76A diet, was updated to produce the AIN-93 diet series in the early 1990s. These AIN formulae may have been customised according to the research objective. Purified high-fat diets provide a nutritionally balanced way to study Diet Induced Obesity, and when compared to a properly matched low-fat diet, they allow the researcher to understand the effects of higher levels of fat on an animal’s phenotype.
50 gm Corn Oil, 3 gm DL- Methionine, 35 gm Minerals, 10 gm Vitamins, 500 gm Sucrose, 50 gm Cellulose, 150 gm Corn Starch, 2 gm Choline, Bitartrate 200 gm Casein:
Total = 1,000 gm
High-Fat Diet-Induced Obesity Models
For understanding the physiology of human obesity, rats and mice are frequently used as animal models since they easily gain weight when provided with a high-fat diet and also develop other risk factors associated with Multiple Sclerosis (MS). Several high-fat rodent diets are available from certified vendors. Not all high-fat diets are the same, since both the level and source of fat may differ between diets. While the majority of research on obesity uses diets with pure ingredients, other studies combine chow with extra fat. The other nutrients (protein, vitamins, minerals, and fibre) are diluted as more and more fat is added to a diet, which might result in nutritional deficiencies. When feeding a high-fat diet, it's obviously not the objective to make the final diet protein deficient, yet the level of fat in the diet should be taken into consideration. The amount of fat in the diet should be taken into account when selecting a pure ingredient diet with more fat. Low-fat diets (LFD) have approximately 10% of their calories from fat, high-fat diets (HFD) have between 30% and 50% of their calories from fat, and very high-fat diets (VHFD) typically have more than 50% of their calories from fat. Comparatively, 10–12% of the calories in the majority of low-fat diets come from fat. Both HFD and VHFD are used to induce obesity, and there is a dose-response relationship between body weight and dietary fat. One must keep in mind that it may be more challenging to reverse the drive to fat on a VHFD, whereas things like compound efficacy may be more detectable when used in conjunction with an HFD, when researching the impact of a medicine, nutraceutical, or gene mutation on obesity.
The origin of dietary fat is also important. "Oils ain't oils," as one researcher said, refers to the fact that not all fats produce the same phenotype. For instance, when mice were administered purified component diets with comparable amounts of fat, those provided with fish oil gained less weight and had higher levels of insulin sensitivity than those fed diets with saturated fats (SF). However, not all studies support this, and it may depend on dietary fat level and gender.On HFD and VHFD, most rats tend to gain weight, but depending on the strain, gender, and source of dietary fat, there can be differences in glucose tolerance, insulin resistance (IR), triglycerides (TG), and other characteristics. Outbred Sprague Dawley and Wistar rats respond differently to an HFD (32 or 45 kcal% fat)(Table 1), with some animals gaining excess weight quickly and others just gaining weight consistent with what they would acquire on an LFD. Initially, chow-based diets were used for this research; however, purified ingredient diets were created and are now frequently used by researchers to divide the rats into DIO and diet-resistant (DR) groups.The outbred Sprague-Dawley DIO and DR rats have also been selectively bred over time so that their future body weight response to an HFD is known in utero. This enables the researcher to search early in life (before the onset of obesity) for genetic traits that may later predispose them to their DIO or DR phenotypes. The inbred obese Zucker diabetic fatty (ZDF) rat is a model for researchers interested in studying obesity and type 2 diabetes. On an LFD, the males develop obesity and diabetes, whereas HFD feeding fosters more severe disease.In spite of being obese, female ZDF rats are unusual and do not acquire diabetes unless fed a diet (chow-based) that contains 48 kcal% fat. The prolonged period of insulin sensitivity prior to the onset of diet-induced diabetes allows the researcher more time to study the female ZDF rat in a pre-diabetic state. Different strains of mice show variability in weight gain on a purified ingredient, VHFD (~60% by energy). While mice of the A/J and SWR/J strains tend to be resistant to obesity, some inbred strains, such as the C57BL/6 or AKR mouse, are particularly prone to obesity on a VHFD. Nevertheless, strains that may display comparable levels of obesity may have different metabolic reactions.
BTL Biotechno Labs Pvt. Ltd., the distributor of Research Diet Inc., is supplying animal diets to the Indian research community for laboratory animals like Mouse, Rats, Zebra Fish, Non-human Primates, Hamsters, Guinea Pigs etc for carrying out in -vivo research. They provide control diets and diet-induced disease models: Diabetes, Obesity, Hypertension, Artherosclerosis, Cancer, Metabolic syndrome, Ketosis etc. In addition to the High-Fat Diet, the other commonly used animal diets are: Growing Rodent Diet, Mature Rodent diet, High Fat Diets, NASH Diets, Methionine- Choline Deficient diets, High-Fructose, High-Cholesterol Diets, Choline Deficient (CD) Diets, Vitamin and Mineral Deficient Diets.
Research Diets, Inc. is the leading manufacturer of custom, purified Open-Source diets and scientific instrumentation for Biological Data Acquisition in laboratory animal models worldwide.
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Research Diets, Inc.