Picking your protein.
Last updated 5/3/2019 at Noon
Excessive carbohydrate calories, especially from the simple sugars glucose and fructose, increase the risk for obesity, high blood pressure, heart disease and even cancer. Cutting back on your daily carbs will mean increasing the fat and protein calories in your diet.
But what kind of fat? And what kind of protein?
Cholesterol and saturated fats have been tagged as major risk factors for blood vessel disease (atherosclerosis) for decades. But recent work suggests they are not the most important factor in all those heart attacks. Merely a late stage contributor to damage already well under way.
The results of numerous studies and investigations points to Trimethylamine N-Oxide (TMAO) as the real culprit.
There is proof of cause and effect. In an experimental mouse model, raising blood TMAO levels by dietary manipulation increased blood vessel disease in the absence of any changes in the cholesterol or fat content.
Numerous clinical studies of heart disease (chest pain in the ER, progression of known atherosclerotic heart disease) show a direct correlation between increasing blood levels of TMAO and cardiovascular disease.
Carnitine, a protein found in red meat and to a much lesser degree in chicken and fish, is the source of TMAO. Any dietary carnitine not digested and absorbed in the small bowel passes into the colon where bacteria (our microbiome) metabolize it to an intermediate molecule, TMA. TMA is in then absorbed and modified further in the liver to TMAO.
There is a similar pathway for the production of TMAO from lecithin, a protein found in egg yolks.
Solid evidence supports diet as the major determinant of blood TMAO levels. A recent study documented that a diet low in red meat and eggs lowered TMAO levels independent of the amount of cholesterol or saturated fats in those diets.
TMAO production can be reduced with oral antibiotics (which alter the makeup of the microbiome) or by decreasing the dietary intake of carnitine. Vegans as a group have the lowest blood TMAO levels (and the lowest rate of cardiovascular diseases) while those on a regular red meat diet the highest. Just replacing red meat with chicken will lower the amount of TMAO excreted in the urine by two thirds.
What does this suggest for your diet?
Carbohydrates should be limited, and this means daily caloric requirements will be replaced by increasing total protein and fat.
Saturated fats, found in butter, cheese, red meat and other animal-based foods, do play a role in the development of cardiovascular disease, but there risk has been overstated.
Your decision on the source of the third component of the daily diet, protein, has considerable impact on your health. We know that vegetarians have the lowest levels of blood vessel disease, and your goal should be a move toward a meat free diet.
But that does not mean you have to become a vegan? You can add one or two meat-free dinners a week. Or decrease red meat portion sizes.
And now we know that your choice of protein, substituting chicken or fish for red meat adds a third option.
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