Low Carb High Fat Diets and the Thyroid - Perfect Health Diet. Last year we ran a series on “Zero- Carb Dangers,” which are health problems that can appear if carb intake – or carb+protein intake, since protein can to some degree make up for a deficit of glucose – are too low. Anthony Colpo has recently argued that hypothyroidism should be added to the list of potential zero- carb dangers; and that low- carb high- fat diets in general might create a risk of hypothyroidism. Similar arguments have been made by Matt Stone and others. Our resident thyroid expert, Mario Renato Iwakura, decided to look more deeply into the matter. What does the literature say? Here’s Mario. There have been anedoctal reports on low carb forums about people becoming hypothyroid after following a low carb, high fat diet. Anthony Colpo recently wrote a blog post about carbohydrate, fat and protein intake and their effects on thyroid hormone levels, concluding that a high fat or high protein diet is detrimental and that a high carbohydrate diet is good for the thyroid . There is no evidence that a diet, such as the Perfect Health Diet, that is high in saturated and monounsaturated fat, low in PUFA, and provides sufficient, moderate levels of protein and carbohydrate, has any detrimental effect on the thyroid. On the contrary, I believe that such a diet is optimal for thyroid health. What Has Been Tested: High PUFA Diets. Colpo’s post is extensive and covered most, but not all, relevant studies published to date about the subject. Many of those studies have problems like short duration or calorie restriction. But in almost all, with the exception of one study by Jeff Volek and collaborators . An example is the Vermont long term study .
The excess fat in these diets averaged 8. So, this diet’s fat was probably 1. Or in Ullrich et al 1. All diets were in liquid form, and fat was predominantly PUFA. The composition of the four diets was: 5. P/1. 0C5. 0P/7. 6C7. P/1. 0C7. 0P/8. 6CEnergy (kcal)5. ![]() Protein (% cal)3. Fat (% cal)5. 7. 8. Carb (% cal)6. 7. Treatment Options for Canine Liver Disease. The course of treatment required in a case of canine liver disease will depend upon the cause of the condition. T3 Day 0. 2. 0. 2. T3 Day 2. 81. 1. 1. Variation- 4. 5%- 2. T3 thyroid hormone levels decreased on all of these severely calorie restricted diets. However, when PUFA was high (5. P/1. 0C and 7. 0P/1. C) the decrease in T3 was much larger than when PUFA was low (5. P/7. 6C and 7. 0P/8. C). In a 1. 99. 2 paper, Vasquez et al compared two very low calorie diets (6. ![]() ![]() The fat sources were soybean oil and refined and stabilized vegetable oils. Ketogenic. Nonketogenic. ![]() Protein. 35%3. 4%Fat. Carbs. 9%5. 1%T3 Day 0. ![]() T3 Day 2. 80. 8. 1. Variation- 4. 3%- 1. The various studies cited by Colpo also show decreases in T3 levels in diets high in PUFA. In Ullrich et al 1. Thyroxine (T4) and reverse T3 (r. ![]() Happy International Whale Shark Day! Learn about how to swim with whale sharks responsibly and then check out these 7 fun facts about whale sharks.T3) did not change significantly. Thyroid- stimulating hormone (TSH) declined equally after both diets”In the Vermont study . When subjects on the low- carb diet began eating the higher- carb mixed weight gain diet, their T3 levels rose. T3 levels among those who went from the high- carb maintenance diet to the mixed diet remained unchanged. In contrast to T3, serum concentrations of T4 were unchanged by overeating or changes in dietary composition.” . Neither do we have studies showing what happen to T3 levels after a high saturated/monosaturated fat diet is eaten. We will have to rely on indirect evidence. Indirect Evidence: Calories Required to Maintain Weight. There is a connection between thyroid activity and obesity. Reduced thyroid activity reduces energy expenditure (“calories out”) and promotes weight gain; normal thyroid function tends to promote normal weight. So we can use the vast number of obesity studies as indirect evidence for the effects of different types of diet on the thyroid. Anthony emphasized this relationship in his post, noting findings of the Vermont study on overfeeding: “Again, that both groups gained weight should come as no surprise. However, the group overfed the mixed diet required more calories (2,6. Baseline differences in metabolism between the two groups were ruled out, as there was no difference in total calories required to maintain initial lean weights.”So the high- PUFA diet promoted weight gain: it caused excess weight to be retained at a lower calorie intake. This is consistent with reduced thyroid activity. Is this effect due to a high- fat diet generally, or to high- PUFA diets only? Some insight into this question may be found in a blog post by Stephan Guyenet . Rats fed isocaloric diets in which the fat source was varied among three groups – a beef tallow group (primarily saturated fat, 3% PUFA), an olive oil group (primarily unsaturated, 1. PUFA), and a safflower oil group (7. ![]() ![]() ![]() PUFA) – had highly variable weight gains. The olive oil group gained 7. Here is the data, expressed in terms of the percentage of baseline calorie intake that the men had to eat to maintain their weight: The high- fat diet consisted largely of butter and cream; the high- carbohydrate diet of extra sugar. When eating the butter and cream, subjects had to eat more calories to maintain weight than when eating the sugary diet – 2. Every subject had to increase calories when eating high- fat. This suggests higher thyroid hormone levels on the high- saturated fat diet than on a high- carb diet. The Volek Study. Anthony cited a study by Jeff Volek and others . There was a significant increase in total T4 (+1. T3 nor r. T3. They instead tested T3 uptake, an indirect measure of thyroxine binding globulin (TBG) in the blood, which tells us little of any real value about changes in actual thyroid hormone levels. The researchers also measured IGF- 1, glucagon, total and free testosterone, sex hormone- binding globulin (SHBG), insulin- like growth factor- I (IGF- I), and cortisol. The only significant change noted was a reduction in insulin following the low- carbohydrate diet. The Volek study is very interesting because it was not calorie restricted (only carbohydrate was restricted) and was done in normal- weight man. The amount of polyunsaturated fat increased a little (from 6 to 1. Although he did not directly measured T3 nor r. T3 we have indirect evidence that they were not impaired. One very well known fact is that hypothyroid patients, even when taking T4 hormones, usually struggle to lose fat. This occurs because, when thyroid hormones are low, especially when T3 (triidothyronine) is low . If the LCHF diet was impairing the thyroid these healthy normal weight men, who had been advised to eat enough calories to maintain their weight during the intervention, should have struggled to lose fat mass. In fact they lost 3. The control group did not lose any weight despite an 1. More, testosterone levels usually decrease when thyroid hormones are low . IGF- 1 levels are also decreased in hypothyroidism . Glucagon levels are higher in hypothyroid patients . Sex hormone- binding globulin (SHBG) is low in hypothyroidism . But none of these parameters changed during the LCHF diet. So this diet which was low in carb (8% of calories) and moderately high in protein (3. PUFA (1. 1%) does not seems to affect the thyroid if saturated and monosaturated fat (5. Let’s compare the fatty acid profile of the Volek diet with that of human milk: Saturated. Monounsaturated. Polyunsaturated. Volek diet. 41%4. Human milk. 47. 5%4. Not too much difference. Perhaps PUFA intake needs to be higher than 1. Effects of high fat and thyroid responses to cold. In 1. 94. 5, Mitchell et al published two articles comparing the effects of proteins versus carbohydrates and fat versus carbohydrate on man’s tolerance to cold exposure . Carbohydrate does better than protein, but worse than fat, at maintaining internal temperature as measured by rectal temperature. On the first experiment, five men consumed a high protein diet (4. P, 4. 0% F, 1. 9% C) and five a high carbohydrate diet (1. P, 4. 1% F, 4. 8% C) for 5. Food intake was adjusted to mantain a constant body weight. The effect of decrement in rectal and mean skin temperature during eight hour exposure to cold with light clothing: Rectal Temp. Skin Temp. High Protein. High Carb. 1. 0. 53. Significance. P=0. P=0. 0. 09. 6On the second experiment, five men consumed a high fat diet (1. P, 7. 3% F, 1. 7% C) and five a high carbohydrate diet (1. P, 2. 3% F, 6. 7% C) for 5. Food intake was adjusted to maintain a constant body weight. The excess fat of the high fat group was provided by butter and cream. Decrement in rectal temperature from the first two hour to the last two hours of 6 hours exposures to - 2. Eating a high carb meal between the intervention did not produced any alteration. But, eating a high fat meal cut the decrement in rectal temperature in half. Thyroid hormones are responsible for basal metabolic rate and heat production. So, if a high saturated fat diet maintains body temperature better than a high carbohydrate diet when the body is subjected to cold, it would seem fair to assume that the thyroid functions better on this high saturated fat diet. Conclusion. A diet with sufficient but not excess protein, moderate carbohydrate comprising a minority of calories, and high intake of saturated and monounsaturated fat but low intake of polyunsaturated fat would seem to be optimal for thyroid function. But this is the Perfect Health Diet! References. Is a Low Carb Diet Bad For Your Thyroid? Body composition and hormonal responses to a carbohydrate- restricted diet. Jul; 5. 1(7): 8. 64- 7. Dietary- induced alterations in thyroid hormone metabolism during overnutrition. J Clin Invest. 1. Nov; 6. 4(5): 1. 33. Effect of low- carbohydrate diets high in either fat or protein on thyroid function, plasma insulin, glucose, and triglycerides in healthy young adults. J Am Coll Nutr. 1. Protein metabolism during weight reduction with very- low- energy diets: evaluation of the independent effects of protein and carbohydrate on protein sparing. Am J Clin Nutr. 1. Jul; 6. 2(1): 9. 3- 1. Protein sparing during treatment of obesity: ketogenic versus nonketogenic very low calorie diet. Apr; 4. 1(4): 4. 06- 1. Carpet shark - Wikipedia. Carpet sharks are sharks classified in the order. Orectolobiformes. Sometimes the common name . Carpet sharks have five gill slits, two spineless dorsal fins, and a small mouth that does not extend past the eyes. Many species have barbels. Characteristics. They first appeared in the fossil record in the Early Jurassic; the oldest known orectolobiform genera are Folipistrix (known from Toarcian to Aalenian of Belgium and Germany), Palaeobrachaelurus (Aalenian to Barremian) and Annea (Toarcian to Bajocian of Europe). Besides the nostrils are barbels, tactile sensory organs, and grooves known as nasoral grooves connect the nostrils to the mouth. Five short gill slits are just in front of the origin of the pectoral fin and the fifth slit tends to overlap the fourth one. The only exception to this rule is the whale shark, the spiracles of which are situated just behind the eyes. The patterning provides camouflage when the fish is lying on the seabed. It is the largest species of fish, but despite its size, is not dangerous, as it is a filter feeder, drawing in water through its wide mouth and sifting out the plankton. The smallest carpet shark, at up to about 3. Cirrhoscyllium expolitum). Nurse sharks and whale sharks have a fringe of barbels on their snouts, and barbelthroat carpet sharks (Cirrhoscyllium expolitum) have barbels dangling from their throat regions. One has been observed swallowing a bamboo shark whole. Some species are oviparous and lay eggs which may be liberated directly into the water or may be enclosed in horny egg cases. Some female sharks have been observed to push egg cases into crevices and this would be an added protection for the developing embryos. Other species are ovoviviparous and the fertilised eggs are retained in the mother's oviduct. There, the developing embryos, which are usually few in number, feed on their yolk sacs at first and later hatch out and feed on nutrients secreted by the walls of the oviduct. The young are born in an advanced state, ready to live independent lives. They are most common in the western Indo- Pacific region and are usually found in relatively deep water. They have two dorsal fins, placed close together on the back, and a relatively short tail. Blind sharks feed on small fish, cuttlefish, sea anemones, and crustaceans. The female retains the eggs in her body until they hatch (ovoviviparity), during which time the embryos feed solely on the egg yolk. Also present on the lower jaw are two fleshy barbels, chemosensory organs which help the nurse sharks find prey hidden in the sediments. Common in shallow, tropical, and subtropical waters, these sharks are sluggish and docile bottom- dwellers. Nurse sharks typically attack humans only if directly threatened. The largest species can reach a length of 4. They have elongated, cylindrical bodies, with short barbels and large spiracles. As their common name suggests, they have unusually long tails, exceeding the length of the rest of their bodies. They are found in shallow waters of the tropical Indo- Pacific. They are sluggish fish, feeding on bottom- dwelling invertebrates and smaller fish. The camouflage is improved by the presence of small weed- like whisker lobes surrounding the jaw, which help to camouflage it and act as sensory barbs. They are found in shallow temperate and tropical waters of the western Pacific Ocean and eastern Indian Ocean, chiefly around Australia and Indonesia. Most species have a maximum length of 1. Wobbegongs are generally not dangerous to humans unless provoked. They are found only in the shallow waters of the western Pacific. They are relatively small sharks, with the largest species reaching no more than 9. It is a slow- moving filter feeder with a very large mouth, feeding mainly, though not exclusively, on plankton. The whale shark is a pelagic species, living in the open sea in tropical and warm oceans with a lifespan around 7. They grow to a length of 2. Indo- Pacific, frequenting coral reefs and sandy flats to a depth of 6. They are nocturnal and spend most of the day resting motionless on the sea floor. They are innocuous to humans. The IUCN has assessed them as vulnerable and some evidence indicates their numbers are dwindling. Allen & Erdmann, 2. Allen, Erdmann & Dudgeon, 2. Allen & Erdmann, 2. Allen & Dudgeon, 2. Richardson, 1. 84. Family Orectolobidae. Gill, 1. 89. 6 (wobbegong sharks). Genus Eucrossorhinus. Regan, 1. 90. 8Genus Orectolobus. Bonaparte, 1. 83. Orectolobus floridus. Last & Chidlow, 2. Orectolobus halei. Whitley, 1. 94. 0. White, 2. 01. 0 (Indonesian wobbegong)Orectolobus maculatus(Bonnaterre, 1. Orectolobus ornatus(De Vis, 1. Orectolobus parvimaculatus. Last & Chidlow, 2. Orectolobus reticulatus. Last, Pogonoski & W. White, 2. 00. 8 (network wobbegong)Orectolobus wardi. Whitley, 1. 93. 9 (northern wobbegong)Genus Sutorectus. Whitley, 1. 93. 9Family Parascylliidae. Gill, 1. 86. 2 (collared carpet sharks). Genus Cirrhoscyllium. H. Smith & Radcliffe, 1. Genus Parascyllium. Gill, 1. 86. 2Family Rhincodontidae(J. Duffin; David M. Martill (2. Proceedings of the Geologists' Association. Retrieved 2. 01. 3- 1. Retrieved 2. 01. 3- 1. Retrieved 2. 01. 3- 1. National Geographic: Daily News. Retrieved 2. 01. 3- 1. January 2. 00. 9 version.^Froese, Rainer, and Daniel Pauly, eds. February 2. 01. 1 version.^Compagno, Leonard J. V. Sharks of the World: An Annotated and Illustrated Catalogue of Shark Species Known to Date. Rome: Food and Agricultural Organization. ISBN 9. 2- 5- 1. 01. January 2. 00. 9 version.^. Queensland Primary Industries and Fisheries. Retrieved 2. 00. 9- 0. Guide to Sea Fishes of Australia (amended ed.). New Holland Publishers (Aust.) Pty Ltd. ISBN 1- 8. 64. 36- 0. February 2. 01. 1 version.^Froese, Ranier; Pauly, Daniel (eds.). Retrieved 1. 7 September 2. IUCN Red List of Threatened Species. Version 2. 01. 1. International Union for Conservation of Nature. Retrieved 1. 8 August 2. IUCN Red List of Threatened Species. Version 2. 01. 3. Retrieved 2. 01. 3- 1. Revista Mexicana de Biodiversidad. Aqua (Miradolo Terme). Aqua International Journal of Ichthyology.
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