Just because certain foods can contribute to the development of goitre does not mean that individuals should avoid them. Experts, in this report by Sade Oguntola, say there is no diet restriction for goitre patients who eat these foods in moderation and adhere strictly to instructions from their physicians on their medication.
Looking into the mirror, Mary Haruna could hardly see the bulge her friend said she saw whenever she engaged in lengthy conversation. “I thought it was an innocent bulge because it was painless,” said the 25-year-old teacher.
But over a two-year period, it got worse. Medical investigation revealed she had goitre, a lump in the neck caused by swelling of the thyroid gland.
A healthy thyroid gland is neither visible nor can it be felt in the neck. But, swelling of this gland in the neck due to goitre can be caused by various reasons, including lack of iodine, cancer, thyroid infection, some medicines or even pregnancy, said Dr Joko Adeleye, a consultant endocrinologist at the University College Hospital (UCH), Ibadan, Oyo State.
There are several causes of this condition and the most common one is iodine deficiency. In fact, the American Thyroid Association stated that globally, approximately 90 per cent of cases are a result of insufficient iodine intake.
Iodine deficiency causes goitre because iodine is needed by two of the hormones of the thyroid glands— thyroxine and triiodothyronine.
The thyroid gland
The thyroid gland makes hormones that help control body temperature, heart rate, and growth. They also control how fast the body uses food for energy. The amount of thyroid hormones in the body may increase, decrease, or both in an individual with goitre.
Usually, thyroid medicine is given to bring thyroid hormone levels back to a normal range in individuals with thyroid goitre. Treatment could also be by the use of radioactive iodine to damage cells in the thyroid gland and decrease the size of the goitre.
Surgery may be done to remove all or a part of the thyroid gland in individuals that cannot take medicines or whose symptoms have worsened.
The most common medicine prescribed for the treatment of hypothyroidism is L-thyroxine, commonly known as the principal thyroid hormone or T4 (levothyroxine).
Currently, there is a lot of confusing information and advice out on foods that people should avoid because they can kick-start or fuel goitre.
People experiencing problems with this organ are asked to avoid foods such as beans, cucumber, broccoli, cauliflower, cabbage, soya and walnuts, called “goitrogens” said to aggravate goitre.
Goitrogens are simply substances that can contribute to the development of a goitre, which is an abnormally enlarged thyroid gland, indicating either over- or under-production of thyroid hormones.
Does goitre require diet change?
Certainly, many foods termed goitrogen are healthy. From beans, soya, cabbage to walnuts, these are food items that evidences suggest can form part of a healthy diet.
“In the days of old, they used to talk about foods such as cabbage and cauliflower that could interfere with thyroid hormones formation in the body,”said Dr Adeleye. “But these are vegetables that are not usually eaten in small amounts here in Nigeria. Moreover, in an environment where salt is well iodized, that should not be an issue.”
What is more, whether a person with goitre would also need to avoid eating foods labelled goitrogen is also dependent on the cause of the problem as well as the presence of other diseases that can affect the functions of the thyroid gland, she declared.
She stated: “A person can have goitre and have normal thyroid function, while another person can have goitre and have excessive thyroid function. It all depends on its cause.”
Although patients with goitre do not have diet restriction but only require ensuring their meals are balanced, Dr Adeleye said eating foods that interfere with thyroid hormone synthesis in moderation may cause no harm.
Timing important
For medication, including those for treating goitre, Professor Olufemi Fasanmade, a consultant Physician/Endocrinologist, Lagos University Teaching Hospital (LUTH), Lagos said individuals with goitre need to take their medications once in the morning and on an empty stomach at least one hour before their meal. This, he said, is to prevent any food-drug interaction that can render the medication less effective.
“Eating foods like soya, cabbage, walnut and pawpaw, labelled goitrogens really do not matter if the patient had followed the instruction of taking it on an empty stomach. If this is done, it would not have any effect,” he declared.
Some medicines can work faster, slower, better, or worse when taken on a full or empty stomach. On the other hand, some medicines will upset the stomach. And if there is food in the stomach, that can help reduce the upset.
Worried about goitrogen foods
There are many goitrogen foods that can promote goitre, including peanuts, millet, and spinach. However, Professor Fasanmade said that individuals only stand such a risk when such foods are consumed in large amounts and over a long period of time.
“Even if a person is taking, say, too much of yam or cassava, and without protein, over a long period of time, such can develop a goitre. So, we are talking of a person who eats cabbage daily for many years.
Also, individuals on goitre medications, like levothyroxine, a thyroid hormone, he said should also avoid taking the medicine alongside coffee.
Studies have shown that calcium-rich foods like milk, coffee and grapefruit juice interfere with the medication. Also, effectiveness of the medication is also influenced by other factors such as age of the patient and other medicines such as iron tablets, calcium carbonate, and aluminium-containing antacids.
Vegetables like broccoli, cauliflower, spinach and cabbage are especially goitrogenic if eaten whole and raw. It is better to shred or boil them. The February 2007 issue of “Food and Chemical Toxicology” reports that if the vegetables are shredded, they lose up to 75 per cent of their isothiocyanate content, and if boiled they lose up to 95 per cent.
Cruciferous vegetables contain sulphur compounds called glucosinolates; and when these compounds are broken down, they produce by-products called isothiocyanates that can produce goitre by blocking the absorption and uptake of iodine by the thyroid gland.
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