Wednesday, May 07, 2008

Beef Raises Insulin More Than Oatmeal

And ...
  • Fish raises insulin more than popcorn.
  • Cheese raises insulin more than white pasta.
This is not news. These findings appeared 11 years ago:

An Insulin Index Of Foods: The Insulin Demand Generated By 1000-kj Portions Of Common Foods, American Journal of Clinical Nutrition, 1997

Among the foods tested, breakfast cereals as a group (Cornflakes, Special K, Honeysmacks, Sustain, All-Bran, muesli, oatmeal porridge) produced a lower insulin score* than protein-rich foods as a group (beef, white fish, cheese, eggs, lentils, baked beans). Foods of equal caloric content were compared.

* Insulin score was calculated as the area under the 120-minute insulin response curve for 1000 kJ of test food, relative to a reference food (white bread). (1000 kJ is about 240 calories.)

A strong insulin response is not always desirable.

The Significance Of Insulin

Insulin is a hormone. It controls the movement of nutrients in the body, notably glucose but also fat and protein. It's an anabolic hormone - one that stores and builds, as opposed to a catabolic hormone - one that breaks down and releases.

Having lots of insulin around, for extended periods of time, can cause problems. Dr. Atkins outlined some of these problems in his 2002 New York Times bestseller, "Dr. Atkins' New Diet Revolution: The Low-Carb Approach That Has Helped Millions Lose Weight And Keep It Off":
  • Insulin encourages fat storage and weight gain. "Hyperinsulinism is what makes it hard for many people to lose weight."
  • "Insulin increases salt and water retention, a recipe for high blood pressure."
  • "Insulin is directly involved in creating atherosclerotic plaques, which, if not controlled, can lead to heart disease."
  • "High insulin levels have been shown to correlate with high levels of triglycerides and low levels of "good" HDL cholesterol."
  • "High insulin levels correlate with increased risk of breast cancer and polycystic ovarian syndrome. Conversely, the lower levels of insulin, the better the survival rates for breast cancer."
What Causes High Insulin Levels?

What we eat can influence insulin levels. The assumption (championed by Dr. Atkins and other low-carb proponents) was that carbohydrates caused the greatest relative rise in insulin, and that:
"Insulin secretion [was] largely assumed to be proportional to postprandial glycemia."
- An Insulin Index Of Foods (See above.)
As you can see from the beginning of this post, the study I cited above did not support those assumptions. Not entirely.

It did find a correlation between glycemic response and insulin response; that is, if blood sugar went up after eating a specific food, insulin went up proportionately. But that correlation "accounted for only 23% of the variability in insulinemia."

Nutrients other than carbohydrate were found to influence insulin levels. "Fish, beef, chicken, and eggs had larger insulin responses per gram than did many of the foods consisting predominantly of carbohydrate."

Even within food groups there was variability. White bread "consistently produced one of the highest glucose and insulin responses." However, "pasta, oatmeal porridge, and All-Bran cereal produced relatively low insulin responses, despite their high carbohydrate contents."

The authors concluded, "Macronutrient composition of foods has relatively limited power for predicting the extent of postprandial insulinemia."

This knowledge was public when Dr. Atkins revised his bestseller. You have to wonder why it wasn't incorporated.


Bix said...

To someone who commented about beef and insulin response ... I thought this was interesting:

Saturated Fatty Acids and Insulin Resistance, The Journal of Medical Investigation, August, 2009:,4/88/_pdf

Anonymous said...

Protein also raises glucagon, which counters insulin, whereas carbs just raise insulin alone.

Anonymous said...

Poster is mistaken about a few items.

The protein group mean here includes BAKED BEANS, with a gigantic insulin response induced by eating 1000 KJ of baked beans. This is skewing the mean of the protein group up very high. In actuality, dropping baked beans moves the group average for protein items very close to the average for breakfast cereals.

Eggs, cheese, and beef all have low absolute amount of insulin produced per 1000 KJ serving, and have low insulin scores (30-50% of the activity of an equal portion of white bread). Except for baked beans, and fish, their scores are close to the lower end of breakfast cereals.

You cannot use this study to compare the insulin response elicited by foods of normal individuals (all subjects in this paper have a normal glucose tolerance test curve, as clearly stated in the study's introduction) to individuals with abnormal carbohydrate metabolism. If your carbohydrate mechanism is impaired, these values COULD be very different.

The insulin response per gram serving for the protein group is very low for everything except cheese, which has a much higher fat content (and thus is more energetically dense than other items on the list), therefore the weight of a 1000KJ serving of cheese will be significantly less than the weight of servings of the other goods on the list. As the energy density of the food goes up, its total weight per 1000KJ serving will go down, and the insulin response per gram will go up.

It's important to compare the absolute insulin responses; cheese is very moderate of the foods surveyed. Yogurt is very high, and it is known that milk is also elicits high insulin responses. The absolute insulin response of cheese is a little higher than eggs, and less than beef. This blogger should be more responsible with his analysis.

Bix said...

Thank you for your comment.

As you can see, beef raised insulin more than oatmeal, fish raised insulin more than popcorn, and cheese raised insulin more than white pasta. For food servings of equal caloric content.

The table of insulin scores is interesting, but as you say, and I agree, individual insulin response will vary ... by individual, by metabolic state, and by other foods eaten. Indeed, it's now known that foods and meals with higher fat content can increase insulin resistance and result in a higher insulin response, assuming beta cells are adequately functioning.