All about fruitarianism with a long-term fruitarian, Lena

carbohydrates proteins fats

Macronutrients: carbohydrates, proteins, fats
  • 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.

  • Raw Food Enzymes Are Digested

    William T. Jarvis, former professor of public health, founder of the National Council against Health Fraud (

    “Enzymes are complex protein molecules produced by living organisms exclusively for their own use in promoting chemical reactions. Orally ingested enzymes are digested in the stomach and have no enzymatic activity in the eater.” 

    Andrea Giancoli, R.D., a spokesperson for the American Dietetic Association:

    Enzymes are proteins and proteins denature with heat, but those enzymes are denatured - and thus inactivated - when they reach our stomachs. Our stomach acids are designed to break down proteins very efficiently.”

  • Secondary Metabolites in Leaves and Stems

    Leaves and stems of plants, green vegetables or leafy greens, are widely consumed by humans. The protein contents are higher than in fruits, and they contain low amounts of sugar.

    Some green vegetables produce secondary metabolites that have bitter or astringent properties and may produce toxic alkaloidal and other compounds such as hemoglutenens. Others produce intestinal enzyme inhibitors, such as lectins, which bind to mucosal surfaces and inhibit digestion, especially that of proteins. 

    Plant secondary metabolism produces a large number of specialized compounds (~ 200.000) that do not aid in the growth and development of plants but are required for the plant to survive in its environment. Specialized compounds from secondary metabolism are essential for communicating with other organisms in mutualistic (e.g. attraction of beneficial organisms such as pollinators) or antagonistic interactions (e.g. deterrent against herbivores and pathogens). They further assist in coping with abiotic stress such as increased UV-radiation.

    The broad functional spectrum of specialized metabolism is still not fully understood.

    Well known specialized compounds include alkaloids, polyphenolsincluding flavonoids, and terpenoids. Humans use quite a lot of these compounds, or the plants from which they originate, for medicinal and nutraceutical purposes.

  • Free Fructose Functions Similar to Fiber

    Fruits contain mostly sugars and fibers, such as pectin, that are extensively fermented in the large intestine. Certain fruits, especially apples and pears, are concentrated in fructose. Apples contain 6% fructose and 3% sucrose and pears are 6.5% fructose and 1.3% sucrose; these values would be consistent in apple and pear juices. Free fructose is poorly absorbed and would function similar to dietary fiber, escaping absorption in the small intestine while being fermented in the large intestine. This results in SCFA production, which is linked to small amounts of energy being absorbed in the colon. 

  • Fruits and Vegetables

    Fruit and vegetable consumption is a focus of research and nutrition education, but there is no universal agreement on the meaning of 'fruits and vegetables'. Foods that require specific instruction include rice, dried beans, potatoes, tomatoes and fruits and vegetables in mixtures and condiments. 

    Fruit and vegetables are important components of a healthy diet, and their sufficient daily consumption could help prevent major diseases. A recently published WHO/FAO report recommends a minimum of 400g of fruit and vegetables per day (excluding potatoes and other starchy tubers) for the prevention of chronic diseases such as heart disease, cancer, diabetes and obesity, as well as for the prevention and alleviation of several micronutrient deficiencies. 

    Fruits and vegetables are universally promoted as healthy. The Dietary Guidelines for Americans 2010 recommend you make one-half of your plate fruits and vegetables.

    Fruits and vegetables include a diverse group of plant foods that vary greatly in content of energy and nutrients. Fruits and vegetables supply dietary fiber, vitamins and minerals to the diet and are sources of phytochemicals (phytonutrients) that function as antioxidants, phytoestrogens, and antiinflammatory agents and through other protective mechanisms. 


  • Protein Intake in Older Age

    Respondents aged 50–65 reporting high protein intake had a 75% increase in overall mortality and a 4-fold increase in cancer death risk during the following 18 years. These associations were either abolished or attenuated if the proteins were plant derived.

    Conversely, high protein intake was associated with reduced cancer and overall mortality in respondents over 65, but a 5-fold increase in diabetes mortality across all ages.

  • USDA Tips for Vegetarians

    Tips for Vegetarians

    Vegetarian diets can meet all the recommendations for nutrients. The key is to consume a variety of foods and the right amount of foods to meet your calorie needs. Follow the food group recommendations for your age, sex, and activity level to get the right amount of food and the variety of foods needed for nutrient adequacy. Nutrients that vegetarians may need to focus on include protein, iron, calcium, zinc, and vitamin B12

  • Carbohydrates

    Carbohydrates are the sugars, starches and fibers found in fruits, grains, vegetables and milk products, one of the basic food groups.

    Sugar is the generalized name for sweet, short-chain, soluble carbohydrates, many of which are used in food. They are composed of carbon, hydrogen, and oxygen. Simple sugars are called monosaccharides and include glucose (or dextrose), fructose, and galactose. The table sugar most customarily used as food is sucrose - hydrolyses into fructose and glucose in the body. Other disaccharides include maltose and lactose. Longer chains of sugars are called oligosaccharides. 

    Starch is a polymeric carbohydrate consisting of a large number of glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants as an energy store. It is the most common carbohydrate in human diets and is contained in large amounts in staple foods such as potatoes, wheat, maize (corn), rice. Pure starch is a white, tasteless and odorless powder that is insoluble in cold water or alcohol. 

    Fiber is consists of non-starch polysaccharides such as arabinoxylans, cellulose, and many other plant components such as resistant starch, resistant dextrins, inulin, lignin, chitins, pectins, beta-glucans, and oligosaccharides, and are derived from plants. Dietary fibers are not digested by gastrointestinal enzymes. Soluble fiber dissolves in water, changes as it goes through the digestive tract, where it is fermented by bacteria, partially into physiologically active byproducts - healthful compounds. Insoluble fiber does not dissolve in water and stays intact as it moves through your digestive system, can be prebiotic and metabolically ferment in the large intestine. Dietary fibers can change absorption of other nutrients and chemicals. Some soluble plant fibers can modulate intestinal inflammation and are contrabiotic. Many types of so-called dietary fiber are not actually fibrous.

  • 5 Main Elements of Healthy Diet by WHO

    From World Health Organization - 5 elements of a healthy diet:

    1) Fruits, vegetables, legumes (e.g. lentils, beans), nuts and whole grains (e.g. unprocessed maize, millet, oats, wheat, brown rice).

    2) At least 400 g (5 portions) of fruits and vegetables a day. Potatoes, sweet potatoes, cassava and other starchy roots are not classified as fruits or vegetables.

    3) Less than 10% of total energy intake from free sugars, which is equivalent to 50 g (or around 12 level teaspoons) for a person of healthy body weight consuming approximately 2000 calories per day, but ideally less than 5% of total energy intake for additional health benefits. Most free sugars are added to foods or drinks by the manufacturer, cook or consumer, and can also be found in sugars naturally present in honey, syrups, fruit juices and fruit juice concentrates.

    4) Less than 30% of total energy intake from fats. Unsaturated fats (e.g. found in fish, avocado, nuts, sunflower, canola and olive oils) are preferable to saturated fats (e.g. found in fatty meat, butter, palm and coconut oil, cream, cheese, ghee and lard). Industrial trans fats (found in processed food, fast food, snack food, fried food, frozen pizza, pies, cookies, margarines and spreads) are not part of a healthy diet.

    5) Less than 5 g of salt (equivalent to approximately 1 teaspoon) per day and use iodized salt.

  • Trusting Sense of Smell to Identify Ripe Fruit

    The interplay between the fruit-eating primates and the tropical fruit trees is an example of coevolution, where species adapt to each others’ needs over millions of years. The plants have an interest in their fruit being eaten when the seeds are ready to be dispersed, and for the animals the value of a fruit is greater when it contains more sugar and nutrients. An unripe banana for instance contains mostly starch.

    Prof. Matthias Laska

    ”This adaptation goes back some fifty thousand years, when the first primates appeared. Initially they ate mostly insects, before eventually trying fruit and vegetables. Some fruit didn’t want to be eaten, so they developed toxic substances. Others acquired better and better odours that signaled energy-rich sugar and nutrients.” 

Dalai Lama

Life is as dear to a mute creature as it is to a man. Just as one wants happiness and fears pain, just as one wants to live and not to die, so do other creatures.


Grains are small, hard, dry seeds, with or without attached hulls or fruit layers, harvested for human or animal consumption. The two main types of commercial grain crops are cereals (e.g. wheat, rye) and legumes (e.g. beans, soybeans). Seeds

After being harvested, dry grains are more durable than other staple foods, such as starchy fruits (e.g. plantains, breadfruit) and tubers (e.g. sweet potatoes, cassava). This durability has made grains well suited to industrial agriculture, since they can be mechanically harvested, transported, stored for long periods, and milled for flour or pressed for oil. Major global commodity markets exist for canola, maize, rice, soybeans, wheat, and other grains but not for tubers, vegetables, or other crops. Apple