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Dietary protein intake influences absorption of Vitamin A
I've long suspected that higher protein intake(beyond adequate) can only do harm to the body. Most of the world besides for Western Europe and North America typically consume much less meat and less often. From personal experience, I've always felt worse on high protein diets(150-220 grams a day), even if all the protein comes from whole foods. As most people know, proteins are primarily processed by the liver, broken down into smaller components to be used by the rest of the body. Any excess protein is actually a burden. Since the body has no real method to store protein, it typically converts the protein to glucose or fat. In excess, protein can but an enormous strain on the liver, and theoretically, could effect the processing and detoxification of food.
While thinking about this information, I also recalled that higher protein diets "use" up Vitamin A. While this is true, I found that protein also increases the absorption of retinol. According to the study below, fat and carbohydrates did not increase the amount of Retinol absorbed. Moderate fat intake had both the lowest absorption rate and the highest excretion rate. Maybe this has something to do with the increased bile?
Some speculation- I am currently looking through some studies on high fat cheese, dairy, and bacterial cultures of cheese in relation to Vitamin A absorption. There were a few studies that were published a few years ago showing how higher dairy fat consumption, in the form of cheese and butter improved a number of health markers. One of the interesting things was, that a lot of the fat from the dairy made into the feces, especially the long chained fats. Harry posted a study earlier showing how the consumption of butter led to lower serum retinol levels in comparison to Vegetable oils. I suspect that fats from high fat cheese(like brie) and butter are not fully absorbed. Since Vitamin A is bound to the long chain fatty acids, maybe the Vitamin is passing through without being fully absorbed. I am also trying to find another study regarding the digestion of butter in the stomach. Apparently, butter is digested very slowly, and can actually sit along the lining of the digestive tract. This means that the Vitamin A is also absorbed more slowly.
Anyways, this is speculation on my part, but I have a feeling that moderate fat consumption along with controlled protein intake(3-4 oz of meat at a time, no more than twice a day) could have a favorable impact. It also explains why high meat intake is typically associated with unfavorable health markers. It also explains why low protein diets almost always improve the health in mice, even if their diet includes supplemental Vitamin A.
Effects of dietary protein, fat and beta-carotene levels on beta-carotene absorption in rats.
Abstract
It is important that the factors influencing functional carotenoid absorption be made clear. The effect of rat diets containing different combinations of dietary protein, fat, and beta-carotene levels on beta-carotene absorption was evaluated. In the mid-level beta-carotene diet groups (1.8 mg beta-carotene/100 g diet), the retinol content in the liver and the ratio of the liver retinol content to the beta-carotene intake (namely, retinol accumulation rate) were both greater in the mid-level dietary protein groups (20 g protein/100 g diet) than in lower dietary protein groups (5 g protein/100 g diet), but were not affected by dietary fat level (10 g or 2 g fat/100 g diet). The liver beta-carotene content and its accumulation rate were lower in the mid-level dietary fat groups (10 g fat/100 g diet). beta-carotene 15,15'-dioxygenase (CDO) activity in the small intestine increased in the mid-level dietary protein groups, which resulted in an increase in the content of liver retinol converted from dietary beta-carotene. With respect to the mid-level dietary fat groups, the fecal beta-carotene excretion rate (%) increased. The low beta-carotene diet groups (0.006 mg beta-carotene/100 g diet) showed a higher serum retinol accumulation rate, CDO activity, and liver beta-carotene accumulation rate than the mid-level beta-carotene diet groups. These results suggest the marked effect of protein, fat, and beta-carotene level in diets on the absorption and metabolism of beta-carotene.
I agree and I believe the same, overdoing protein does not make any sense and most cultures thrive on starch based diets, blue zones included. But then I think of the Andersens, who had been eating ribeye for 17 or so years. A lot of fat but hardly low/moderate protein (they eat 2-5lb meat/person if I remember correctly). Their diet is lacking bc though. How to eat regarding macros is probably more relevant when one is not already toxic?
I would like to see someone do a similar dietary study on animals who are poisoned by vit A already, as most of us in here are. To see how the different macros affect storing/releasing/reuptake of vit A.
Animal studies are always interesring. But what needs to be remembered is that animals are not humans and result/effect may therefore differ. This happens a lot in research when finding a new drug which works on the animals, but the desired result when taking it to human trials is not there. That doesn't mean animal studies are pointless because they are not. We learn a lot from them. Please post the other link when you find it 🙂
I have been on a lower vitA diet since june (excluding all dairy, eggs, liver and high bc veggies like kale and carrots) and strict since mid-november (that is when the magic started happening) .
Right before going strict i did a caseine experiment where I introduced cheese. A high quality unpasteurized generic sardinian cheese, the same kind the centrinarians eat. It took 2 hours for my skin to start itching and eczema to start forming. Immediately I got a runny nose and thick throat. I did not have a protein heavy diet beforehand and I have no allergy, which is what I thought at first and therefore had it checked. It could be the fat is beneficial, but the A it contains wrec more havoc than it benefits. Or so it feels.
I tried butter a few weeks back, which was my third butter episode since going strict, my severe back pain returns when I do. Every time. My little body is def affected by its vit A content. But dr G believes butterfat to be good to eat during detox, imo it seems to be individual and I'd very much like to understand why this is. I'd love to eat butter during detox especially if it can be beneficial.
Regarding the protein heavy diet.. Since maybe one week back I have noticed I crave a LOT of meat. Meat and salt and fat. I wonder why this is... 🤔 The meat craving I get a few times a year usually, where i eat a lot of meat for a few days up to a week, then the craving goes away and I return to my normal diet. There must be some sort of feedback system behind this but what?
I think dr G has a study posted in his forum, about the carrot man whose serum retinol was low but liver was full and his RBP levels were low ans not saturated. They changed his diet and included more protein as well and the parameters changed. If I remember correctly he ate a low protein low fat diet to start with.
Oops, this got long 🙈 sorry 😬
There are plenty of studies that show that fats increase VA absorption as well. And butter seems to increase absorption of VA even more than other fats.
"Dark green leafy vegetables are primary food sources for lutein and β-carotene, however these bioactives have low bioavailability. The effects of mechanical and thermal processing as well as fat addition and fat type on lutein and β-carotene liberation and in vitro accessibility from spinach were investigated. Lutein liberation and in vitro accessibility were three-fold higher from spinach puree compared to whole leaves. Results for β-carotene liberation were similar, whereas that of β-carotene accessibility was only about two-fold. Steaming had no or a negative effect on carotenoid liberation. Fat addition increased β-carotene liberation from raw and steamed puree, but reduced lutein liberation from steamed leaves and raw puree. Fat types affected β-carotene differently. Butter addition led to a 2.5 fold increased liberation from raw spinach puree, while the effect of olive and peanut oil was significantly lower, but only minor effects were observed for lutein."
https://www.sciencedirect.com/science/article/pii/S0308814616319951
Peanut butter and lard increases VA absorption: https://www.ncbi.nlm.nih.gov/pubmed/28917229
Quote from Guest on January 6, 2019, 2:33 amThere are plenty of studies that show that fats increase VA absorption as well. And butter seems to increase absorption of VA even more than other fats.
"Dark green leafy vegetables are primary food sources for lutein and β-carotene, however these bioactives have low bioavailability. The effects of mechanical and thermal processing as well as fat addition and fat type on lutein and β-carotene liberation and in vitro accessibility from spinach were investigated. Lutein liberation and in vitro accessibility were three-fold higher from spinach puree compared to whole leaves. Results for β-carotene liberation were similar, whereas that of β-carotene accessibility was only about two-fold. Steaming had no or a negative effect on carotenoid liberation. Fat addition increased β-carotene liberation from raw and steamed puree, but reduced lutein liberation from steamed leaves and raw puree. Fat types affected β-carotene differently. Butter addition led to a 2.5 fold increased liberation from raw spinach puree, while the effect of olive and peanut oil was significantly lower, but only minor effects were observed for lutein."
https://www.sciencedirect.com/science/article/pii/S0308814616319951
Peanut butter and lard increases VA absorption: https://www.ncbi.nlm.nih.gov/pubmed/28917229
It's probably true but what if there are no other sources of beta carotene and retinol in the diet?
So butter increase uptake of betacarotene (due to butyric acid creating RBP?) more than other sources of fat? And second guest above, how does fat in a diet affect the released vitamin A if no other sources are coming in? Is the released vitamin a being re-stored, or is fat actually helpful to detoxify? I haven't figured this out and it might be individual as well. If I eat vit a free with no added fat, i.e. Rice, beans, lean meat for a few days I start feeling flu symtoms in my throat and more tired. When adding fat (light olive oil) it goes away but if i add fats every day I dont get the same immediate effect. Grant has done fine on a fairly low fat diet though. But so are Garrett's clients eating butter 😳