Rhonda - here is an explanation. It is more information than you asked for but I think the rest is interesting so I am including it. It came from a website about natural remedies:
Natural Remedies for Thyroid, Hypothyroid, Goiter, Hypothyroidism, Underactive Thyroid. Extra Virgin Coconut Oil. Canada.
"Consumption of soybean oil and soy products (soy has proven thyroid suppressing properties). This is why soybeans are used so extensively in feeding livestock, as they cause reduced metabolism and more rapid weight gain. On the contrary, the lauric acid in coconut oil stimulates thyroid function. In the 1940's, farmers tried giving their livestock coconut meal as a cheap food, and found that their animals became lean rather than fatter."