All about fruitarianism with a long-term fruitarian, Lena

Modern diets are largely heat-processed and as a result contain high levels of advanced glycation end products (AGEs), also known as glycotoxins. Dietary advanced glycation end products (dAGEs) are known to contribute to increased oxidant stress and inflammation, which are linked to the recent epidemics of diabetes and cardiovascular disease.

Dry heat promotes new dAGE formation by 10-100 times above the uncooked state across food categories. Animal-derived foods that are high in fat and protein are generally rich in glycotoxins and prone to formation of new glycotoxins during cooking. Carbohydrate-rich foods such as vegetables, fruits, whole grains (but also milk) contain relatively few glycotoxins, even after cooking.

The formation of new glycotoxins during cooking was: 

  • prevented by the AGE inhibitory compound aminoguanidine
  • and significantly reduced by
    • cooking with moist heat,
    • using shorter cooking times,
    • cooking at lower temperatures,
    • and by use of acidic ingredients (such as lemon juice or vinegar).

Advanced glycation end products (AGEs), are a diverse group of highly oxidant compounds with pathogenic significance in diabetes and in several other chronic diseases. Glycotoxins are created through a Maillard or browning reaction - it is a part of normal metabolism, but if excessively high levels of glycotoxins are reached in tissues and the circulation they can become pathogenic, which is related to their ability to promote oxidative stress and inflammation by binding with cell surface receptors or cross-linking with body proteins, altering their structure and function.

Glycotoxins also exist in foods: they are naturally present in uncooked animal-derived foods, and cooking results in the formation of new AGEs: grilling, broiling, roasting, searing, and frying propagate and accelerate new AGE formation. Recent studies clearly show that dAGEs are absorbed and contribute significantly to the body’s AGE pool.

Avoidance of dAGEs, glycotoxins in food, helps delay chronic diseases and aging in animals and possibly in human beings.

Glycotoxins in the diet represent pathogenic compounds that have been linked to the induction and progression of many chronic diseases. High temperature and low moisture consistently and strongly drive their formation in foods. Comparatively brief heating time, low temperatures, high moisture, and/or pre-exposure to an acidified environment are effective strategies to limit new formation in food.

A significantly reduced intake of dAGEs can be achieved by reducing intake of solid fats, fatty meats, full-fat dairy products, and highly processed foods, and by increasing the consumption of legumes, vegetables, fruits, and whole grains. 

Low-AGE–generating cooking methods are 

  • poaching,
  • steaming,
  • stewing, 
  • boiling.

For example, the high AGE content of broiled chicken (5,828 kU/100 g) can be significantly reduced to 1,124 kU/100 g when the same piece of meat is either boiled or stewed. 

Future studies should continue to investigate the health effects of AGEs and refine recommendations for safe dietary intakes. However, current data support the need for a paradigm shift that acknowledges that how we prepare and process food may be equally important as nutrient composition.

Isaac Bashevis Singer

What do they know-all these scholars, all these philosophers, all the leaders of the world - about such as you? They have convinced themselves that man, the worst transgressor of all the species, is the crown of creation. All other creatures were created merely to provide him with food, pelts, to be tormented, exterminated. 

Protein Structure, Cooked and Denatured Proteins

Proteins are chains of amino acids. The sequence of amino acids in a chain is known as the primary structure of a protein. The chains fold up to form complex three dimensional shapes. The chains can fold on themselves locally (secondary structure) and wrap around themselves to form a specific three dimensional shape (tertiary structure).

The secondary / tertiary structure of a folded protein is directly related to its function. For example, enzymes are proteins that catalyze reactions. They have binding sites that interact with other molecules. These binding sites are created through the folding of the amino acid chains that gives rise to the three dimensional shape of the enzyme.

Denatured Protein

Denaturation of proteins involves the disruption and possible destruction of both the secondary and tertiary structures. Since denaturation reactions are not strong enough to break the peptide bonds, the primary structure (sequence of amino acids) remains the same after a denaturation process. Denaturation disrupts the normal sheets in a protein and uncoils it into a random shape.

Denaturation occurs because the bonding interactions responsible for the secondary structure (hydrogen bonds to amides) and tertiary structure are disrupted. In tertiary structure there are four types of bonding interactions between "side chains" including: hydrogen bonding, salt bridges, disulfide bonds, and non-polar hydrophobic interactions. which may be disrupted. 

Proteins can be denatured through exposure to heat or chemicals. Denatured proteins lose their three dimensional structure and thus their function. 

Digestion of Proteins and Cooking

Protein digestion begins in the stomach, where the acidic environment favors protein denaturation. Denatured proteins are more accessible as substrates for proteolysis than are native proteins. The primary proteolytic enzyme of the stomach is pepsin, a nonspecific protease that is maximally active at pH 2. Thus, pepsin can be active in the highly acidic environment of the stomach, even though other proteins undergo denaturation there.

Heat disrupts hydrogen bonds and non-polar hydrophobic interactions. This occurs because heat increases the kinetic energy and causes the molecules to vibrate so rapidly and violently that the bonds are disrupted

Foods are cooked to denature the proteins to make it easier for enzymes to digest them. Cooking food denatures some of the proteins in it and makes digestion more efficient. Heating to denature proteins in bacteria and thus destroy the bacteria.

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