Does combining antioxidant vitamins make them more potent?
Here’s a quick quiz for you. Milk contains two primary types of
protein, whey and casein. Studies show that they’re absorbed at
different rates, with whey being absorbed rapidly and casein slowly
releasing amino acids into the blood for more than seven hours. Which
would suppress appetite more? A new study focused on just that
question.1 Past studies have shown that protein has a greater satiation
effect than fat or carbs. On the other hand, the appetite-suppressing
effect of protein is blunted in people who habitually eat a high-protein
diet—typical of bodybuilders. That’s most noticeable in those who
increase their protein intake from a lower level. With a regular
higher-protein intake, amino acids are more rapidly cleared and oxidized
from the blood, mitigating its effect on appetite.
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That’s also the reason a high-protein diet isn’t likely to lead to
increased fat deposition, since all nutrients, including protein, fat
and carbs, can be converted into fat. Active people, such as those
engaged in regular exercise, burn up excess protein in the liver, thus
preventing its conversion into glucose or fat.
One notable difference between whey and casein is that the amino
acids in whey are rapidly processed and absorbed into the blood. Casein,
on the other hand, curdles in the stomach, leading to a much slower
breakdown and release of amino acids. Because a high concentration of
amino acids is vital for promoting muscle protein synthesis, some
studies suggest that whey’s rapid release of aminos makes it superior to
casein for that purpose. On the other hand, casein’s slow release of
amino acids makes it more conducive to providing a pronounced
anticatabolic effect by maintaining a positive nitrogen balance in the
blood over the course of several hours.
The amino acids in the blood dictate the appetite-suppressing
properties of protein. Whey is the superior appetite-suppressing
protein. In a new study, subjects drank a beverage containing 48 grams
of a commercial whey supplement or one containing the same amount of
casein and attended an all-you-can-eat buffet 90 minutes later. Those
who drank the whey ate 19 percent less food than those who drank the
casein.
In the second part of the study researchers wanted to confirm the
notion that the quick entry of amino acids made whey more satiating and
to figure out if any gut hormones known to affect appetite were affected
by whey or casein. That part of the study showed, as expected, that
whey increased blood amino acid levels 28 percent more than casein over a
three-hour period.
The whey drink increased the levels of several gut hormones that are
known to suppress appetite. It increased the blood levels of
cholecystokinin (CCK) by 60 percent, glucagonlike peptide-1 by 65
percent and glucose-dependent insulinotropic polypeptide by 36 percent.
That last hormone isn’t normally increased by protein alone, but both
the whey and casein drinks also contained cream and maltodextrin, a
quick-acting carbohydrate.
Thus, whey appears to decrease appetite through its rapid release of
amino acids, which in turn promotes the release of several gut hormones
known to depress appetite and increase feelings of satiety.
1 Hall, W.L., et al. (2003). Casein and whey exert different effects
on plasma amino acid profiles, gastrointestinal hormone secretion and
appetite. Brit J Nutrition. 89:239-48.
©,2015 Jerry Brainum. Any reprinting in any type of media, including electronic and foreign is expressly prohibited
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