A DIFFERENT DIABETES: LATENT AUTOIMMUNE DIABETES OF THE ADULT (LADA)

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WHAT IS LADA?

Latent Autoimmune Diabetes of the Adult (LADA) is a type of autoimmune diabetes which shares common features between type 1 and type 2 diabetes.It is also called Type 1.5 diabetes or slowly progressive autoimmune diabetes.The 3 common criteria for diagnosis of LADA are:
  • Adult onset:the age at diagnosis ranges from 15 to 30 years.However, nowadays Type 2 diabetes is being diagnosed in increasingly younger people.The youngest person to be diagnosed with type 2 diabetes is a three year old girl in Texas, USA.
  • Antibody positivity: Diabetes Associated Antibodies (DAA) are usually present in people with LADA.However this may not be quite so clear-cut, given that different laboratories may have different cut-off values.These DAA include antibodies to glutamic acid decarboxylase 65 (GAD 65), insulinoma-associated antigen, islet cell & zinc transporter 8. The commonest is GAD 65 antibody.Antibody levels may fluctuate and the type of positive antibody may change over a period of time.Even a transient increase in autoantibody indicates autoimmunity.
  • Insulin treatment: Arbitrary definition of LADA include a period without insulin treatment of at least six months, but the need to use insulin is usually at the discretion of the physician.

WHY DO YOU NEED TO KNOW IF YOU HAVE LADA?

  • Patients with LADA generally have worse HbA1c levels (measure of 3 month’s average blood sugar) than type 2 diabetes patients.
  • Often they are misdiagnosed as type 2 diabetes.Incorrect treatment will lead to higher loss of insulin producing beta cells of pancreas.
  • Studies have shown that patients with LADA need insulin treatment earlier than those with type 2 diabetes and therefore may need closer monitoring.
  • Patients with LADA have lower levels of C-Peptide. (Connecting peptide is a marker of insulin production by your body). C-Peptide levels influence treatment.
  • The sulphonylurea group of drugs like chlorpropamide,glyburide,glipizide etc which work by stimulating the pancreas to release more insulin, are not the right choice of drugs for people with LADA.
  • Despite greater use of insulin, patients with LADA have worse blood sugar control. Therefore there is something more that needs to be done.
  • When any one autoimmune condition is present, the chances of developing others are high. People with LADA have a higher incidence of thyroid autoimmunity. Hence it is important to screen for other diseases as well.

WHAT IS DIFFERENT ABOUT A FUNCTIONAL AND METABOLIC MEDICINE APPROACH?

In addition to testing for DAA we would look at the following:

  • Gut Health.
  • Gut dysbiosis
  • Intestinal Permeability Dysfunction (Leaky Gut)
  • Vitamin D3 levels
  • Chronic Inflammation
  • Sleep
  • Nutrient Depletion
  • Stress Response
  • Movement/Exercise
  • Test for other autoimmune conditions, particularly thyroid autoantibodies.
  • Risk for heart disease and stroke
  • Check for heart failure.

Should everybody be screened for LADA?

That will depend on your goals.I practice patient-participatory medicine. My duty as a physician is to provide you with correct information and help  you make the best decision for yourself.

You MAY BE INTERESTED IN READING:

Do you have autoimmune diabetes

Predictive Autoantibodies

Vitamin D and Autoimmunity

Ebook on Autoimmunity

REFERENCES
Gambelunghe, Giovanni, et al. "Increased risk for endocrine autoimmunity in Italian type 2 diabetic patients with GAD65 autoantibodies." Clinical endocrinology 52.5 (2000): 565-573.
Priyanka P. Brahmkshatriya, Anita A. Mehta, Banshi D. Saboo, and Ramesh K. Goyal, “Characteristics and Prevalence of Latent Autoimmune Diabetes in Adults (LADA),” ISRN Pharmacology, vol. 2012, Article ID 580202, 8 pages, 2012. doi:10.5402/2012/580202

DO YOU HAVE AUTOIMMUNE DIABETES?

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WHY DO YOU NEED TO KNOW IF YOU HAVE DIABETES AUTOIMMUNITY?

Sonia Kumar (not her real name) a 38 year old mother of two young girls, spent seven frustrating months trying to get her blood sugar under control.She was recommended escalating doses of oral anti-diabetes medications. She was even accused of cheating on her diet!But none of this helped her! It took an astute physician (not me!) to test her for diabetes autoantibodies to find out that she actually had Type 1 Diabetes!

The diagnosis was missed because people often think that Type 1 Diabetes does not develop in adults.

WHAT IS DIABETES?

Diabetes is a group of metabolic diseases with high blood sugar (hyperglycaemia) as the common feature. The high blood sugar results from defects in insulin secretion, defects in insulin action or both. About 20 years ago diabetes was classified into Insulin Dependent (IDDM) or Juvenile and Non-Insulin Dependent (NIDDM) or Adult Onset Diabetes. However, in the last several years it has become apparent that the use of insulin or age at onset could not adequately explain the disease conditions and specify the best treatment plan. Therefore, there is an opinion amongst diabetes researchers that the time has come for a new classification of the disease.

Diabetes develops because of an interaction between genes and the environment. Our genes have not changed in thousands of years,but our environment has.To a great extent this explains the dramatic increase in diabetes over recent years. Some of the influences have originated in the intrauterine environment before a person is born!

Exposure to environmental toxins like BPA have also contributed to the recent epidemic of diabetes.

Developments in the field of precision medicine, ethnicity-specific data and big data along with patient-participatory research will change the management of diabetes for the better.

TYPES OF DIABETES:

(For a medically appropriate classification please check the American Diabetes Association website for “Etiologic classification of diabetes mellitus”).

  • Type 1 Diabetes
  • Type 2 Diabetes (Commonest)
  • Gestational Diabetes (GDM/Pregnancy Diabetes)
  • Maturity Onset Diabetes of the Young (MODY)♣
  • Latent Autoimmune Diabetes of the Adult(LADA)♣
  • Drug Induced Diabetes.♣
TYPE 1 DIABETES

High blood sugar resulting from an absolute deficiency of insulin secretion. Type 1 Diabetes may be

  • Autoimmune or
  • Idiopathic.

Autoimmune Diabetes occurs when the Insulin producing cells in the pancreas are destroyed by an autoimmune process. Autoimmune markers for Type 1 Diabetes, also called Diabetes-Associated Autoantibodies (DAA) are usually present in most of these patients.

Idiopathic—In a small percentage of patients there is Insulin deficiency but no autoimmunity.

Though absolute insulin deficiency is a hallmark of Type 1 Diabetes, about 30 % of people with this condition have insulin resistance as well.

DIABETESASSOCIATED AUTOANTIBODIES (DAA):

  • Glutamic Acid Decarboxylase Autoantibodies (GAD65 or Anti-GAD)
  • Insulin Autoantibodies (IAA)
  • Insulinoma-Associated-2 Autoantibodies (IA-2A)
  • Islet Cell Cytoplasmic Autoantibodies (ICA)
  • Zinc Transporter 8 (ZnT8Ab) Autoantibodies
GESTATIONAL DIABETES (GDM or PREGNANCY DIABETES)

GDM is defined as any degree of glucose intolerance that was first recognized during pregnancy. This definition would include women who had previously undiagnosed Type 2 Diabetes and also those women who developed diabetes for the first time during pregnancy.Asian Indian women are at a very high risk for pregnancy diabetes. Therefore it is very important for them to be screened at the beginning , during mid-trimester as well as in the last trimester.

GDM raises the risk of several complications in both the mother as well the baby. Increased birth defects, increased birth weight, early (preterm) delivery are some of the risks in the babies born of mothers with GDM. The mother is at increased risk of pregnancy high blood pressure and pre-eclampsia and is at a higher risk for developing diabetes later in life. In addition, she is at increased risk for heart disease even if she does not develop diabetes later on in life!

TYPE 2 DIABETES

This is the commonest type of diabetes.Type 2 diabetes includes individuals who have insulin resistance and usually relative insulin deficiency. These individuals may not need insulin treatment to survive. However, use of insulin does not decide the type of the disease. Diabetes Associated Autoantibodies are absent in people with Type 2 Diabetes.

HOW DOES THIS AFFECT YOU?

It is important to keep in mind that adults can develop autoimmune diabetes too! British Prime Minister Theresa May, who was diagnosed with Type 1 Diabetes at age 56 and Sonia Kumar mentioned above were both initially diagnosed as Type 2 Diabetics. However both of them needed insulin therapy to control their blood sugar levels,when they were found to have Diabetes Antibodies.

Sulfonylurea (SU) drugs like chlorpropamide,glyburide,glipizide which work by stimulating the pancreas to release more insulin, are not the right drugs for these people.Use of these drugs in patients with diabetes autoimmunity have shown poor metabolic control and earlier loss of insulin producing beta cells in the pancreas.

A study in apparent long-standing type 2 diabetes found that those with Diabetes Associated Autoantibodies or with low C-peptide did not respond well to glucagon-like peptide 1 (GLP-1) agonist drugs like Liraglutide,Exenatide etc.

People with one autoimmune condition are at a higher risk for other autoimmune conditions as well. Diabetes Autoimmunity has often been associated with thyroid autoimmunity.

NUMBERS TO KNOW

If you have diabetes you obviously know your blood sugar and glycated haemoglobin (HbA1C) levels. In addition the following tests are important for the right treatment:

  • Diabetes Associated Autoantibodies (DAA)
  • C-Peptide ♣ :This  test can indicate how much insulin your body is producing.

(♣ Separate blog posts on these topics later.)

As Dr. Elliott P. Joslin, (who was the first doctor in the United States to specialize in diabetes and the founder of Joslin Diabetes Center) wrote “ . . . unless the physician takes care, he will fall into schematic ways and forget that it is the patient who comes for treatment and not the diabetes. Each is a case unto itself.” 

 

REFERENCES

Mohan V, Usha S, Uma R. Screening for gestational diabetes in India: Where do we stand? Journal of Postgraduate Medicine. 2015;61(3):151-154. doi:10.4103/0022-3859.159302.
Goueslard, Karine, et al. "Early cardiovascular events in women with a history of gestational diabetes mellitus." Cardiovascular diabetology 15.1 (2016): 15.
Leslie, R. David, et al. "Diabetes at the crossroads: relevance of disease classification to pathophysiology and treatment." Diabetologia 59.1 (2016): 13-20.
Brophy S, Davies H, Mannan S, Brunt H, Williams R. Interventions for latent autoimmune diabetes (LADA) in adults. Cochrane Database of Systematic Reviews 2011, Issue 9. Art. No.: CD006165. DOI: 10.1002/14651858.CD006165.pub3.

CIRCADIAN DISRUPTION: ARE YOUR MEALTIMES AFFECTING YOUR METABOLISM?

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Your body has an internal biological clock which decides when you sleep, eat, wake up, secrete hormones, process food and do many more functions.

The term circadian comes from the Latin word circa, meaning “approximately”, and diēm, meaning “day”. This daily rhythm is related to Earth’s rotation around its own axis which exposes all living beings to a 24-hour light-dark and temperature cycle.

Chronobiology is the science or study of the effect of time, especially rhythms, on living systems (including humans).

In the last several years many scientific studies have shown that the disruption of the circadian rhythm is related to a higher incidence of many conditions like Type 2 Diabetes, heart disease, inflammation, mood disorders, some cancers and obesity. In fact, rotating night shift–work has been called a probable carcinogen (cancer causing) by the World Health Organization. Night shift work and light at night(LAN) have been associated with a higher risk for breast cancer in women.

BASICS OF CIRCADIAN RHYTHM

Your body’s circadian rhythm is controlled by a circadian clock. The master clock is in the brain (Suprachiasmatic Nucleus SCN) and this controls all the other clocks in the other organs (peripheral clocks). Every cell in your body has this intrinsic clock and there are genes involved in the clock mechanisms. In fact, the clock is present even in cells in a petri dish in the lab!

Clocks

Fig: Central clock in the Suprachiasmatic Nucleus in the brain and peripheral clocks in different organs.Zeitgebers: Light on retina and food intake.

Although circadian rhythms are built-in and self-sustained, external cues can modulate circadian rhythms.

What are the external cues (zeitgebers) modulating your circadian rhythm?

  • Light falling on your eyes.

(Nerd Alert: Retinal melanopsin influences this. Loss of melanopsin retinal cells may be related to dysregulation of circadian rhythm in  Alzheimer’s Disease )

  • Intake of food
  • External temperature.

CHRONONUTRITION:

Chrononutrition refers to food intake in coordination with your body’s daily rhythm. This concept implies that in addition to the type of food you consume, the time of ingestion is also critical for your health and well-being.

STUDY USING A SMARTPHONE APP:

In an interesting study reported in the journal Cell Metabolism (2015), Dr. Satchidananda Panda and Shubhroz Gill used a smartphone app to track eating patterns in healthy men and women who were living regular lives (not in a lab). The smartphone app was used to take pictures of everything that they ate or drank. This was done for 3 weeks.

WHAT DID THEY FIND:

  • Most food (53.6%) was consumed after 6 PM, with less than 25% of caloric intake occurring before noon.

(My comments: Why is this important? This is related to your insulin secretion and insulin sensitivity. Lower Insulin sensitivity (IS) means higher body fat percentage and higher risk for Type 2 Diabetes and a whole host of diseases.) IS tends to be higher at breakfast than at lunch or dinner. So if most of your food intake occurs at a time of the day when you are less insulin sensitive, what can happen? You can become metabolically dysregulated and insulin resistant. This is a big problem in Asian Indians because diabetes and heart disease strikes them at least a decade before it does in the Western population. My dictum is “all Asian Indians are either pre-diabetic or diabetic until proven otherwise”)

  • Only 25% of the meals occurred after >6 hours 41 min of fasting.
  • About 90 % of people in the study ate for 14 hours 45 minutes in a day.
  • In another part of the study, 8 people who ate for more than 14 hours in a day, were asked to reduce their eating duration to 10-12 hours and to follow the same pattern during week days and weekends.

What did they find?

  • In 16 weeks of study duration the participants lost 3.27 kilograms of body weight!
  • These 8 people on the time restricted eating (TRE) program reported better sleep, better energy levels and less hunger at bedtime.
  • These people voluntarily agreed to stay on this eating pattern and they maintained their weight loss and sleep improvement and higher energy levels 1 year after they started on TRE. All this improvement from just restricting your eating from >14 hours to 10-12 hours! This is major!

Though the study did not mention testing for inflammatory markers or blood sugar and insulin, I am sure if they had measured, they would have found improvements in these biomarkers as well.

Weight loss is not a simple problem of calorie-in-calorie-out(CICO). I prefer to say fat loss because your weight includes your muscles and bones too. You don’t want to lose muscle! (More on this later).

ACTION STEPS:

  • Download and use the app (REFERENCES SECTION) and track for yourself. You will get great insight.
  • Implement Time Restricted Eating and see the difference in your health.
  • Eat an early dinner: This is a big challenge in many Asian Indian homes but try moving your dinner time by half hour every week until you have your dinner around 6:30-7 PM everyday.May be difficult to change dinner time from 9:30 PM to 6:30 PM in one day.
  • I know some of you do not reach home in time to have an early dinner. Maybe you can carry a second box of home cooked food to eat in the office or on the commute.
  • If you reach home by 7 PM, have your dinner at that time  instead of eating snacks then and save yourself from a late dinner just before you go to bed.

(Watch for post on “metabolic/social” jetlag ,later)

REFERENCES:

myCC

Picture:App myCircadianClock.

Android:https://play.google.com/store/apps/details?id=com.salk.mycircadianclock&hl=en

iTunes:https://itunes.apple.com/ca/app/mycircadianclock/id982118665?mt=8

La Morgia, Chiara, et al. “Melanopsin-expressing retinal ganglion cells: implications for human diseases.” Vision research 51.2 (2011): 296-302. La Morgia, Chiara et al.

Melanopsin Retinal Ganglion Cell Loss in Alzheimer Disease.” Annals of Neurology 79.1 (2016): 90–109. PMC. Web. 18 Aug. 2016.

Gill, Shubhroz, and Satchidananda Panda. “A smartphone app reveals erratic diurnal eating patterns in humans that can be modulated for health benefits.”Cell metabolism 22.5 (2015): 789-798.

Time for Food: The Intimate Interplay between Nutrition, Metabolism, and the Circadian Clock Asher, Gad et al. Cell, Volume 161, Issue 1, 84 – 92

Saad, Ahmed, et al. “Diurnal pattern to insulin secretion and insulin action in healthy individuals.” Diabetes 61.11 (2012): 2691-2700.

 

 

THYROID AND IODINE: ARE YOU GETTING ENOUGH IODINE ?

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Iodine is an essential component of thyroid hormone production.Iodine is the naturally occurring element, which is a solid at room temperature. Iodide is the form when it combines with another element like potassium or sodium, which is usually what is added to iodised salt.Most iodide is found in the oceans and evaporates into the atmosphere and is returned to the soil by rain. Soil and groundwater can become iodine deficient because the iodine cycle is not as efficient in many geographical regions of the world.Iodine deficiency is common in many hilly and mountainous regions of the world.
IODINE DEFICIENCY DISEASES:
Iodine deficiency is associated with many conditions, all of them related to thyroid function.
In Adults:
  • Goitre
  • Hypothyroidism
  • Impaired mental function.

In pregnancy:

  • Miscarriage
  • Stillbirths
  • Congenital anomalies.
In newborns and children:
  • Cretinism
  • Mental retardation
  • Neonatal goitre
  • Neonatal hypothyroidism.
  • Developmental delay
The biggest problem of iodine deficiency occurs when pregnant women are deficient in this mineral, because mental retardation in the child as a result of iodine deficiency is irreversible.Studies have shown that even in mildly iodine deficient women children were born with lower IQ.
WHERE DO YOU GET YOUR IODINE?
Your body does not make iodine so you have to get it from food or supplements.Iodine content in food can vary because the quantity present in soil varies.
The commonest sources of iodine are:
  • Seaweeds like kelp, nori,wakame.
  • Eggs, dairy.
  • Some fish
  • Iodized salt
  • Supplements

IODIZED SALT:

Worldwide iodine deficiency diseases are still a major public health problem in many countries.Mountainous areas, such as the Himalayas, Alps, and Andes regions, and river valleys prone to flooding, especially in South and Southeast Asia, are among the most iodine-deficient regions in the world.To counter the adverse effects of this condition the program of salt iodization was started in many countries.

Salt iodization is a process whereby potassium iodide is added to common salt during the manufacturing process so that people consuming adequate amounts of iodized salt will not be iodine deficient. Iodized salt was first available in the United States in 1924. Though populations  in United States and Canada are considered to have adequate iodine levels, according to the Statistics Canada website,a 2009 study among Canadians aged 3 to 79, showed that a moderate deficiency of urine iodine levels was found in 7% of the population while 15% had an excessive intake.A deficiency and an excess are both cause for concern.
 In India several studies have shown that despite a program of salt iodization since the 1960ties, goiter and other Iodine Deficiency Disorders still remain a problem in many regions.

HOW MUCH IODINE DO YOU NEED IN A DAY?

The standard recommendation is:

  • Non-pregnant adults 150 microgram/day
  • Pregnant and breast feeding women 250 microgram/day. However, the recommendations for the upper limit vary from 500-1,100 mcg of iodine daily.
  • Tolerable upper limits of iodine intake: 1100 microgram/day

CAN YOU GET ADEQUATE IODINE FROM IODIZED SALT?

This is open to debate because of various reasons. The amount of iodine present in the iodized salt depends on the conditions of storage, relative humidity and the packaging material used. In fact, a 2008 study from the US states that “Forty-seven of 88 samples (of Iodized salt) fell below the USFDA recommended Iodine content while 6 exceeded it.” 

The World Health Organization (WHO) recommends that you should take 5 grams of salt a day. This quantity of iodized salt should ideally contain 400 microgram of Iodine. However, most people use a lot more salt than the recommended 5 grams. A lot of the salt intake is from processed food which is not iodized salt. Excess salt has been associated with higher incidence of high blood pressure.

Instead of getting your iodine from iodized salt perhaps it is better to get it from a multivitamin multimineral supplement containing 150 microgram of Iodine.

IS THERE A PROBLEM OF TOO MUCH IODINE?

According to the American Thyroid Association (ATA) the tolerable upper limit of iodine intake is 1100 microgram per day. In fact, the ATA advises against the ingestion of iodine and kelp supplements containing in excess of 500 mcg iodine daily. A study from China in The American Journal of Clinical Nutrition (2012) shows that amongst euthyroid (normal thyroid function) adults subclinical hypothyroidism appeared in the participants who took 800 μg/d of Iodine.

Therefore, excess iodine intake can be harmful and has been associated with :

  • Hyperthyroidism
  • Hypothyroidism
  • Congenital hypothyroidism because of excess Iodine intake by mother.

High doses of Iodine are sometimes recommended by some practitioners. It is often quoted that the Japanese people living in Japan consume very high amounts of Iodine through their diet of seaweed. Is it possible that the Japanese people have a different gut microbiota which helps them process the excess iodine differently? (Reference: Dr. Justin Sonnenburg, PhD, “Microbiology: genetic pot luck.” Drs Justin and Erica Sonnenburg have written an excellent book The Good Gut: Taking Control of Your Weight, Your Mood and Your Long-term Health)

High doses of iodine are appropriate in the treatment of severe hyperthyroidism before thyroid surgery and as potassium iodide following a nuclear accident. However, this is always done by a qualified physician.

HOW DO YOU KNOW IF YOU HAVE IODINE DEFICIENCY?

This question does not have a simple answer.

Urine Iodine Concentrations: Iodine levels cannot be reliably measured in individuals because of the considerable day-to-day variation in iodine intake. Median urinary iodine concentrations (UIC) have been widely used as a biomarker of population iodine intake. This does not necessarily apply to individuals.

Thyroglobulin: Serum thyroglobulin can be used as a marker of iodine levels in the body. However, this is not a test in isolation of other thyroid function tests. Sometimes Anti Thyroglobulin Antibodies may interfere with the test result. Also keep in mind that Thyroglobulin is not a test for thyroid cancer. (Thyroid Function Tests)

Dried Urine Iodine Test: This test is easily available in USA and Canada and is done by special laboratories. Though not done in India, samples can be shipped to USA and tested. Some testing companies also test Bromine, Fluorine, Thyroglobulin, and some heavy metals in addition to Iodine.

KEY POINTS

  • Iodine is very important for thyroid health.
  • Low iodine in pregnant women is avoidable but irreversible cause of mental retardation in children.
  • Pregnant women must ensure adequate iodine intake BEFORE pregnancy. Extra iodine is needed during pregnancy and breast feeding. Check your antenatal vitamins contain adequate iodine.
  • Iodine deficiency exists even in iodine-adequate countries.
  • Excess iodine intake has adverse effects.
  • Iodized salt may not be best source of iodine.
  • Supplement with multivitamin multimineral containing at least 150 micrograms of Iodine.

YOU MAY LIKE READING

Dietary Goitrogens

Thyroid Hormone Replacement

Hashimoto’s Thyroiditis

REFERENCES 

  1. http://www.statcan.gc.ca/pub/82-625-x/2012001/article/11733-eng.htm
  2. Dasgupta, Purnendu K., Yining Liu, and Jason V. Dyke. “Iodine nutrition: iodine content of iodized salt in the United States.” Environmental science & technology 42.4 (2008): 1315-1323.
  3. Diosady, L. L., et al. “Stability of iodine in iodized salt used for correction of iodine-deficiency disorders. II.” Food and Nutrition Bulletin 19.3 (1998): 240-250.
  4. De Groot, Leslie, et al. “Management of thyroid dysfunction during pregnancy and postpartum: An Endocrine Society clinical practice guideline.” The Journal of Clinical Endocrinology & Metabolism 97.8 (2012): 2543-2565.
  5. Sang, Zhongna, et al. “Exploration of the safe upper level of iodine intake in euthyroid Chinese adults: a randomized double-blind trial.” The American journal of clinical nutrition 95.2 (2012): 367-373.
  6. Leung AM, Braverman LE. Consequences of excess iodine. Nature reviews Endocrinology. 2014;10(3):136-142. doi:10.1038/nrendo.2013.251.
  7. Hehemann, Jan-Hendrik, et al. “Transfer of carbohydrate-active enzymes from marine bacteria to Japanese gut microbiota.” Nature 464.7290 (2010): 908-912.
  8. Sonnenburg, PhD, Justin L. “Microbiology: genetic pot luck.” Nature 464.7290 (2010): 837-838.
  9. Zimmermann, Michael B., et al. “Assessment of iodine status using dried blood spot thyroglobulin: development of reference material and establishment of an international reference range in iodine-sufficient children.” The Journal of Clinical Endocrinology & Metabolism 91.12 (2006): 4881-4887.

DIETARY GOITROGENS AND THYROID FUNCTION: IS THERE A LINK?

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This blogpost was prompted by a comment on a Whatsapp group about dietary goitrogens and thyroid disease. That discussion was related to soy. 
If you have hypothyroidism,the most important question that you’d like to be answered is:
Should you avoid food like soy and cruciferous vegetables (dietary goitrogens)?
 
WHAT ARE GOITROGENS?
According to Wikipedia “Goitrogens are substances (whether in drugs, chemicals, or foods) that disrupt the production of thyroid hormones by interfering with iodine uptake in the thyroid gland. “
( In this post i will not discuss drugs or endocrine disrupting chemicals that affect thyroid function).
What are the common food that well-meaning healthcare practitioners sometimes ask you to avoid if you have hypothyroidism?
The commonest ones are soy and cruciferous vegetables. Cabbage, kale,broccoli, brussels sprouts,bok choy, cauliflower are the commonest cruciferous vegetables that you eat.
SOY AND GOITRE
The alleged association of soy with goitre has probably originated in animal studies and few isolated case studies reported in the sixties ,where few infants fed a soy formula had developed goitre.
What is the true association of soy and thyroid function? In an article in the journal Thyroid (2006) the authors looked at 14 trials (though thyroid function was not the primary health outcome in any trial). They commented that “the findings provide little evidence that in euthyroid, iodine-replete individuals, soy foods, or isoflavones adversely affect thyroid function.”
What about soy interfering with supplemental thyroid hormone absorption?
An interesting case study reported in Endocrine Practice: May 2001 discusses a patient who needed very high doses of thyroid hormone replacement after she had undergone a thyroid gland removal for cancer.On enquiry it turned out that she was taking a “soy-cocktail “protein supplement immediately after taking her synthetic thyroid hormone! Once the intake of both were separated, she needed a lesser dose of thyroid hormone!So this was not a problem of soy being a goitrogen, but a problem of food interfering with  thyroid pill absorption.
Is it only soy that interferes with supplemental thyroid hormone absorption? NO!
Iron, calcium, proton-pump inhibitors like Omeprazole,coffee, cholestyramine and other food also interfere with thyroid absorption. 
This is why we recommend that you should take your thyroid pills on an empty stomach. Preferably avoid eating or drinking anything (other than water) one hour before and one hour afer taking your thyroid meds.Another suggestion from my practice partner Dr.Natasha Iyer is to take your thyroid meds in the middle of the night if you wake up to use the washroom. But no nibbling then!
What about cruciferous vegetables as goitrogens?
In animal studies very high intake of cabbage and turnip have been associated with hypothyroidism.However, animal studies cannot be extrapolated to humans!
A study reported in the New England Journal of Medicine, May 2010 talks about an 88 year old Chinese woman who was brought to the emergency department in myxedema coma (severe hypothyroidism leading to coma).She did not have thyroid dysfunction before. She was taking 1 to 1.5 kilograms of raw bok choy everyday for several months in the belief that it would take care of her diabetes! I don’t know whether her diabetes was affected of but it sure sent her into coma!
However, a small study which  looked at 10 people who ate 150 grams of cooked Brussels Sprouts everyday for 4 weeks, did not show any adverse effects on thyroid function.
IMPORTANT TAKEAWAYS
  • If you have hypothyroidism you can eat soy, cabbage, bok choy, cauliflower, broccoli, kale as long as you do not over-indulge!
  • Supplemental thyroid hormones should be taken away from food or supplements for best absorption.
You may be interested in reading the following posts:
(Watch for post on iodine and thyroid to be posted later).
REFERENCES
  1. Bell, MB, FACE, David SH, and Fernando Ovalle, MD. “Use of soy protein supplement and resultant need for increased dose of levothyroxine.”Endocrine Practice 7.3 (2001): 193-194.
  2. Chu, Michael, and Terry F. Seltzer. “Myxedema coma induced by ingestion of raw bok choy.” New England Journal of Medicine 362.20 (2010): 1945-1946.
  3. McMillan, M., E. A. Spinks, and G. R. Fenwick. “Preliminary observations on the effect of dietary brussels sprouts on thyroid function.” Human & Experimental Toxicology 5.1 (1986): 15-19.