Flavors and culinary experience
We find proteins in most foods. Except for oils or having a black coffee with nothing else in it, proteins exist in the majority of the ingredients you use. It is remarkable that out of milk, humans could create several hundred types of cheeses. A young cheese tastes so much different than one that has ripened. Those made in the mountains bring with them the flavors of the grass the cow ate, the nuance of the cow’s breed, the climate from colder regions and their influence on the final flavor of the cheese. Tasting it makes us travel to the mountains, by proxy, even if we are at this time far away from elevations. Perhaps, like me you love the flavors of cheese, or perhaps you love steaks, fish, or for vegans, the many spices and variations that can make a particular dish feel different when you eat it. All these include proteins, and scientific findings indicate that this macro-nutrient needs special attention to dosing, that is, how much of it we consume. This makes it particularly important to find quality proteins that we enjoy, savor, so they give us pleasure as much as providing metabolic fuel.
Role and types of proteins
From birth to death, our lives depend on being able to consume them and process them to keep our body functioning and growing. They are the structural component of every cell we are made of. All enzymes, membrane carriers, molecules that transport blood, intracellular matrices, fingernails, serum albumin, keratin, collagen and even some hormones and membranes are proteins. They are made primarily of amino acids, and there are many of them.
Amino acids are classified in 3 categories[1].
- Indispensable: histidine, isoleucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine. The body needs every one of them to function, and it is not able to synthetize any of them.
- Dispensable: alanine, aspartic acid, asparagine, glutamic acid, serine. These amino acids exist but we can function without their presence.
- Conditionally indispensable: arginine, cysteine, glutamine, glycine, proline, tyrosine. Like the indispensable one, our life depends on their supply, but the difference is that in most cases the body is able to synthetize them. One caveat, the synthesis requires what’s called precursors, that is, the ingredients for the body to make them. These precursors are glutamine, glutamate, aspartate, methionine, serine, glutamic acid, ammonia, choline, phenylalanine.
The diversity of amino acids puts an emphasis on the need to diversify the types of foods we eat. While carrots supply a wonderful food that’s rich in some nutrients, eating only carrots will leave anyone in a state of severe deficiencies. You get the idea: eating only pastas with the same accompanying sauce, the same sides all the time is also a bad idea. The family of amino acids above are found in a variety of foods and it’s only by exposing ourselves to a complete enough panel that we can give our body what it needs.
Another way of categorizing proteins, derived from the concepts above, is by foods. Some of the foods provide what’s called a complete protein – they include all nine essential amino acids, while other foods provide an incomplete set. You can mix and match complete and incomplete protein sources. In this case, you need to get enough of the indispensable amino acids, the conditionally indispensable ones and if your body has to synthetize them, their precursors.
Those who regularly consume meat and other animal products can easily access complete proteins. Nutrients from meat, fish, eggs, milk, cheese, and yogurt provide all nine indispensable amino acids[2]. For plant-based foods, you have to look for soybeans and quinoa for complete proteins, but getting the complete panel is not as easy. Many fruits, nuts and vegetables are incomplete. So it seems like a good idea for vegetarians to consume at least some animal products, and for vegans to pay extra attention in making sure they are getting all the amino acids their body needs.
Minimum and upper limits
The short answer to how much of anything we need per day, other than what we shouldn’t consume and whose answer is zero, comes down to a personal assessment beyond the scope of this book. The needs of an infant are not the same as the needs of a middle-aged adult, and it continues to vary as we age. Within the same age, we do not have the same absorption capabilities. Some of us are much more physically active, requiring more total energy. But for the general population, it can be useful to understand the recommended protein intakes with what science knows to this day.
Starting the longer answer: there is debate on what the recommended intake is for the average adult, and there is also debate whether over consuming proteins has harmful effects. In other words, hormesis, the dose response, exists in all almost aspects of life and it would not apply to protein consumption? According to the Institute of Medicine[3] the risk from excess intake appears to be “very low”. It recommends a daily allowance (RDA) of 0.80 g per kg of body weight. So, for someone who weighs 160 lb, or 68 kg, it adds up to 54.4 grams. Now, this amount is the amount of proteins, not the amount of food that contains them. 50 grams of beans contains 5 grams of protein, only 10% of what one needs to cover the daily requirement.
As far as the general population in America, the average for men in their 30s and 40s is above 100 grams[4], much higher than the RDA. It is possible the sampled population had an average weight above the example of 160 lb, but this would put the average weight of the sampled population at nearly 300 lb. At least in America and possibly in other industrialized nations, the average person consumes a lot more proteins than the recommended amount.
Excess proteins are likely dangerous
Valter Longo believes excess proteins are not neutral, and rather, have a harmful and damaging effect on our metabolism. In other words, he sees an upper limit, a dose response, amounts where proteins nourish, and amounts in which proteins destroy. Longo studied their impact in multiple settings, starting with mice:
It is difficult to perform studies on specific human diets in mice and other simple organisms. However, basic research yields a fundamental understanding of the connection between food components, aging, and disease. For example, we know that proteins (amino acids) consistently accelerate aging in most organisms, including yeast, flies, and mice. We also know that IGF-1 and TOR-S6K, both of which are increased or activated by protein intake, are central promoters of aging and age-related diseases in mice. In a recent study testing many combinations of food components, mice given a low-protein, high-carbohydrate diet lived the longest but also displayed improved health. Mice on a high-protein, low-carbohydrate diet lived the shortest and had the worst health, despite the effect of the diet on weight loss.[5]
He also notes the works from The Okinawa Program, and the fact that Okinawan population has cancer incidence far lower than that of the United States, a higher life expectancy, while Okinawans consume significantly less meat and animal products as a percentage of their diet. But other studies[6] highlight that age matters. Being particularly cautious with the amount of protein seems to benefit humans especially before the age of 65. Older than this, there may be fewer downsides to proteins, perhaps because we absorb them less efficiently, and they are less likely to stimulate growth hormones and ageing pathways from that point on.
Animal and plant-based proteins
Measurements of vegetarian, semi-vegetarian diet which include fish, and non-vegetarian diet indicate that individuals who avoid animal products produce superior scores in health metrics. The Adventist Health Study #2 observed 773 subjects with a mean age of 60 years[7]. The idea was to group the subjects by their full-, semi- and non-vegetarian lifestyles and assess each group’s metabolic risks. The risks included:
- HDL cholesterol levels
- Triglycerides
- Glucose levels
- Systolic blood pressure
- Diastolic blood pressure
- Waist circumference
- Body-mass index (BMI)
Vegetarians scored better on all metrics for the above risk factors. The study also measured the realization of the risk, which is the occurrence of metabolic syndrome. 39.7% of non-vegetarians tested positive, versus 37.6% incidence for semi-vegetarians, and 25.2% for vegetarians. Overall, the consumption of animal products was detrimental. It is not possible to say from this study that plant-based proteins are less harmful than those found in animal products, because the outcomes may be due to other nutrients in the respective diets. But results do suggest that plant-based nutrients overall, including proteins, provide a safer option, once again as long as individuals find complete protein sources and avoid deficiencies.
Experiments from The China Study provide a more explicit data point. Colin and Thomas Campbell measured the incidence of foci development. Foci is a cluster of cells within an organ that have mutated and are considered precancerous. After showing that increasing the percentage of animal protein (casein, found in cow milk) in mice diet to 20% significantly increases the formation of foci, they repeated the experience with gluten. Gluten is a protein from plant source. At 20% gluten protein, the formation of foci was significantly lower[8].
50 grams of proteins per day add up quickly
If the average adult needs about 50 g of proteins in a day, what does this look like in terms of food? I wanted to test my own perception, and felt that yesterday was a relatively modest day of total calorie intake, mostly from plant sources. Does this equate to 20 g, 50 g, or more? I had no idea, because to this day I focus more on total calories and food quality, than asking myself how much protein there is in each of these ingredients. Longo points out that the people he talks to have no idea either – in fact they confuse grams of food with grams of protein the food contains!
| Breakfast | |
| Type | Estimated protein (g) |
| 2 bread slices | 7 |
| 1 avocado | 3 |
| 1 grapefruit | 1 |
| 1 banana | 1.5 |
| Americano (coffee) | 0 |
| Lunch | |
| Type | Estimated protein (g) |
| 1 cup dry oatmeal | 5 |
| Olive oil | 0 |
| 1 avocado | 3 |
| 1 tomato | 1 |
| Early dinner | |
| Type | Estimated protein (g) |
| 1 egg | 7 |
| 2 cups green beans | 3.6 |
| 1 tomato | 1 |
| Olive oil | 0 |
| 2 ounces of tuna | 12 |
| Total proteins (g) | 45.1 |
I expected a much lower total, as I first wrote down what I ate. Then, I realized that it doesn’t take a lot of tuna to get lots of proteins. Another way of looking at the result is that 2 ounces of tuna and an egg, the two sources of animal products in the entire day, contributed 19 out 45 g, 42% of total proteins.
Try to do the exercise for yourself, it is easy nowadays to calculate the totals using an app on your mobile phone or searching a food database and add up the protein count. You might be surprised the first few times, but as you learn the value of typical foods you consume for their weight, you will know the approximate values without having to look them up or enter them in an app. It’s very similar to heart rate monitors. When you’ve never used one, you don’t know how slow or fast your heart beats when you sleep, when you sit, walk slowly, run easy, run in endurance mode, or sprint. But after you use the device for months, you notice that your endurance heart rate is mostly the same every time – unless of your course your fitness level changes dramatically. So, you can estimate your heart rate at any time of the day with decent accuracy even without the tool on your wrist.
Summary on protein intake
Contrary to reports not finding an upper limit on protein intake, eating them in excess looks like a recipe for metabolic syndrome and the development of other illnesses. It is as important to avoid deficiencies as it is to avoid over consumption. In the proper dose, plant-based proteins look safer than animal products. Enjoy them thoroughly if you are going to eat them, they come in different flavors and taste delicious and addictive, hence why overconsumption is so frequent.
[1] Page 146-147, Dietary Reference Intakes: The Essential Guide to Nutrient Requirements, National Academy of Science, ISBN 978-0-309-10091-5 | DOI 10.17226/11537, https://www.nap.edu/catalog/11537/dietary-reference-intakes-the-essential-guide-to-nutrient-requirements
[2] Page 691, Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids, National Academy of Science, ISBN 978-0-309-08537-3 | DOI 10.17226/10490, https://www.nap.edu/catalog/10490/dietary-reference-intakes-for-energy-carbohydrate-fiber-fat-fatty-acids-cholesterol-protein-and-amino-acids
[3] [3] Page 152, Dietary Reference Intakes: The Essential Guide to Nutrient Requirements, National Academy of Science, ISBN 978-0-309-10091-5 | DOI 10.17226/11537, https://www.nap.edu/catalog/11537/dietary-reference-intakes-the-essential-guide-to-nutrient-requirements
[4] What we eat in America, NHANES 2013-2014, https://www.ars.usda.gov/ARSUserFiles/80400530/pdf/1314/Table_1_NIN_GEN_13.pdf
[5] Longo, Valter. The Longevity Diet: Discover the New Science Behind Stem Cell Activation and Regeneration to Slow Aging, Fight Disease, and Optimize Weight (p. 66). Penguin Publishing Group. Kindle Edition.
[6] Low protein intake is associated with a major reduction in IGF-1, cancer, and overall mortality in the 65 and younger but not older population; Cell Metab. 2014 Mar 4;19(3):407-17. doi: 10.1016/j.cmet.2014.02.006. https://www.ncbi.nlm.nih.gov/pubmed/24606898
[7] Vegetarian Dietary Patterns Are Associated With a Lower Risk of Metabolic Syndrome, PMCID: PMC3114510
PMID: 21411506, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3114510/
[8] Chart 3.8: Protein Type and Foci Response. Campbell, T. Colin; Campbell II, Thomas M.. The China Study: Revised and Expanded Edition: The Most Comprehensive Study of Nutrition Ever Conducted and the Startling Implications for Diet, Weight Loss, and Long-Term Health (p. 51). BenBella Books, Inc.. Kindle Edition.
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