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High salt consumption can contribute to type 2 diabetes, a study suggests. J. Anthony/Stocksy
  • People who add table salt to their food are at a higher risk of developing type 2 diabetes, according to a new study.
  • The study uses the frequency with which one adds salt to their food as a means of assessing their overall sodium intake, including sodium that is cooked into the foods they eat.
  • It may be that sodium promotes hypertension and inflammation, both known risk factors for type 2 diabetes.

Regular dietary sodium intake at meals is associated with an increased risk for type 2 diabetes (T2D), according to a new study. Table salt is a compound consisting of sodium and chloride.

The study found that those who said they “sometimes, “usually,” and “always” added salt to their meals appeared to increase their risk of type 2 diabetes by 11%, 18%, and 25%, respectively, compared to those who added salt “never” or “rarely.”

The new study analyzed data from 402,982 diabetes-free participants in the UK Biobank from March 2006 to October 2010. Individuals ranged in age from 37 to 73.

As a means of identifying factors that might confound the study’s analysis, participants filled out a touch-screen questionnaire that inquired about personal details that have been associated with the development of type 2 diabetes.

These included age, sex, education level, income, smoking status, level of physical activity, alcohol consumption, and the Townsend deprivation index. The deprivation index results in a composite measurement of several lifestyle factors, including unemployment, non-car ownership, non-home ownership, and household overcrowding.

Participants were followed for a mean of 11.9 years, by which time 13,120 people had developed type 2 diabetes.

The risk of type 2 diabetes for people with a higher BMI and a less favorable waist-to-hip ratio was increased further for the “sometimes, “usually,” and “always” people by 33.8%, 39.9%, and 8.6%, respectively.

The study is published in Mayo Clinic Proceedings.

The study’s senior author, Dr. Lu Qi, said, “Our data suggests higher adiposity may partly account for the connection.” Adiposity is the amount of body fat one carries. Adipocytes and adipose tissue store most of the body’s lipids.

Lipids are fatty compounds in cell membranes, managing what enters and exits them. As such, they’re important for storing and distributing energy throughout the body and making hormones. Lipids, however, include triglycerides and free cholesterol, and an excess of lipids — a condition called dislipidemia — has been associated with diabetes.

Type 2 diabetes refers to the condition in which the cells of the body become resistant to the hormone insulin, which is made by your pancreas and helps to manage blood sugar levels.

The result is that one has too much glucose, or sugar, in the bloodstream.

The body needs sugar for fuel, but an excess can cause nervous, circulatory, and immune system disorders.

Michelle Routhenstein, cardiology dietitian and owner of entirelynourished.com, not involved in the study, said:

“Research is unclear on the exact physiological connection, but speculates that it is due to inflammation, blood-vessel lining damage, and potential links between salt, high blood pressure, and insulin resistance.

“It is also important to note that many sodium-rich foods also have saturated fat in them that can increase insulin resistance and type 2 diabetes.”

Assessing individuals’ actual intake of salt is difficult, and studies often opt to analyze a single day’s urine as a means of determining salt intake. Since an individual’s sodium levels are likely to vary from day to day, this may be insufficient to gain a full picture of their sodium consumption. The new study takes a different approach.

Previous research has indicated that a more accurate approach is recording the frequency people add salt to their meals to measure their overall intake, including salt added to foods during preparation.

The idea is that how frequently someone adds salt to their food reflects their taste for salt.

It is not a perfect method — while it provided an accurate measure of salt consumption for most Americans, it did less well for non-Hispanic Black, those with self-reported hypertension, and those with a high school degree or less.

Routhenstein noted that it is not just salt that has been linked to the development of diabetes: “Other foods that have been associated with a higher incidence of T2D include refined sugars, refined carbohydrates, and red and processed meats.”

Dr. Qi said that, in general, the study’s findings can be “applied to the general population, except those with low blood pressure.”

“Based on this study,” said Routhenstein, “limiting your salt intake may help to avoid developing T2D.”

“We also need to note that there are many factors involved, and we should look at the entire diet and lifestyle factors to reduce your risk of T2D and heart disease.”

She added, “According to the research, non-Hispanic African Americans retain more sodium and have more salt sensitivity.”

“This is important to note since the response to salt may have a stronger effect in this ethnic group, and therefore needs to be monitored more closely,” said Routhenstein.

Hispanic, American Indian, Asian American, and Pacific Islander people are also especially susceptible to developing diabetes. They are not alone. People older than 45, individuals with overweight or obesity, and physically inactive people are also at an elevated risk. Other risk factors include hypertension, a family history of diabetes, and having gestational diabetes during pregnancy.

People exhibiting the following symptoms of the disease should consult their physician and be particularly careful about their salt consumption:

  • a need to urinate frequently
  • frequently feeling very thirsty
  • remaining hungry, even when eating
  • having extreme fatigue
  • experiencing blurry vision
  • finding that bruises and cuts are taking a long time to heal
  • experiencing pain, tingling, or numbness in the hands and feet.