Protein - Protein Sources, Quality and Amino Acid Combining Flashcards
1
Q
Protein sources
A
- Protein is found in all whole foods, incl. fruits and honey. Only processed foods (e.g. refined sugar and oils) have no protein.
- A rich and varied diet with sufficient calories supplies a good intake of proteins.
2
Q
Specific protein diets
A
- Specific amino acids and higher protein diets can be therapeutic for certain people or in certain life stages (during pregnancy, athletes, injury recovery etc.)
3
Q
Endogenous sources
A
- The adult human body reabsorbs about 50g of protein per day from shed mucosal cells and 17g per day from digestive enzymes and glycoproteins –these are endogenous sources.
4
Q
Best dietary sources
A
Abundant dietary sources of protein include:
* Legumes
* Nuts/seeds
* Greens
* Whole grains
* Eggs
* Fish
* Poultry and Meat.
5
Q
Meat sources
A
- Meat provides more protein than non-meat sources, but requires more energy to digest than plant sources. Heavy animal protein can accumulate in the intestinal wall, impairing absorption. In addition, what is often added to meat dishes reduces its benefit. e.g., a hamburger with bacon & cheese brings with it high calories, trans-fats, heterocyclic amines & nitrosamines (cancer-risk factors).
6
Q
Resources
A
- There are lots of online resources for checking the protein content of specific foods – these resources will usually detail all macronutrient and some micronutrient parameters too.
- Some great resources to investigate:
o Staying Healthy with Nutrition – prescribed text.
o The World’s Healthiest Foods – website and book.
o The Encyclopedia of Healing Foods.
7
Q
Protein Quality
A
- Protein digestive ability and amino acid composition are said to determine ‘protein quality’.
- The digestibility of most animal protein vs. plant protein is variable due to a variety of factors including gut function (i.e. HCl and digestive enzymes), the presence of fibre and some anti-nutrient factors in plant sources such as phytates and lectins.
- To support the digestibility of plant protein sources, consider soaking, sprouting and fermenting which can lower anti-nutrient factors.
- Plant sources also contain fibre, prebiotics, phytonutrients and other ‘qualities’ which can make them a superior choice for everyday healthy eating.
8
Q
Optimising protein digestion
A
- Chew thoroughly and avoid drinking with meals.
- Support stomach acid levels:
o Zinc and B6-rich foods (need for HCl production).
o Apple cider vinegar in a little water before meals.
o Bitter herbs and foods before meals (e.g. dandelion, rocket, watercress, artichoke, gentian, barberry bark, goldenseal). These also promote the release of pancreatic juice.
o Use betaine hydrochloride supplements with at least 600mg per capsule. Start with one when starting to eat, before increasing one capsule per meal up to a total of 5 max or until a feeling of warmth. If warm, cut one pill back.
9
Q
The microbiome, fermentation and protein digestion
A
- The microbiome contributes to protein metabolism: undigested protein that reaches the colon is fermented, creating toxic metabolites that increase the inflammatory response and encourages the proliferation of opportunistic pathogens.
- Many of the fermentation products of protein are detrimental to health (e.g. ammonia, amines, sulphides, and N-nitroso compounds), with effects including systemic toxicity, nephrotoxicity, and carcinogenesis.
- Therefore, not overloading the body with protein is an important step. Furthermore, optimising protein digestion is crucial to ensure that as little as possible reaches the colon undigested (see later).
10
Q
Amino Acid Composition:
A
- To make proteins, a cell must have all the required amino acids available simultaneously; if one essential amino acid is missing, a cell will have to cease making the protein or must dismantle another protein to obtain it.
- If an essential amino acid is supplied in less than the amount needed to support protein synthesis, it is called a limiting amino acid.
- The limiting amino acids are lysine, threonine, methionine, and tryptophan. They are found in the shortest supply from incomplete proteins. For example, beans are low in methionine. This indicates the importance of rotating the sources to provide balance.
11
Q
Complete protein:
A
- Food that contains all nine essential amino acids.
- Vegan foods that are complete proteins includes:
o Quinoa
o Buckwheat
o Pumpkin seeds
o Chia seeds
o Hemp seeds
o Tempeh - Animal foods:
o Meat
o Poultry
o Fish
o Eggs
o Dairy (except butter)
12
Q
Incomplete protein:
A
- Food is low in one or more of the essential amino acids.
- Most plant foods have an incomplete protein profile — one or more essential amino acids are missing (i.e. the limiting amino acids).
13
Q
Amino Acid Combining
A
- Plant foods can be combined to ensure that the essential amino acids are obtained. This ensures the limiting amino acid in one food is included in a food it is combined with.
- For example, combine:
o Legumes + nuts / seeds
o Whole grains + legumes
o Vegetables + grains.
14
Q
Amino Acid Combining table
A
Food: Beans
Limiting AA in Food: Methionine
Complementary Foods: Grains, nuts, seeds
Food: Grains
Limiting AA in Food: Lysine, threonine
Complementary Foods: Legumes
Food: Nuts & Seeds
Limiting AA in Food: Lysine
Complementary Foods: Legumes
Food: Vegetables
Limiting AA in Food: Methionine
Complementary Foods: Grains, nuts, seeds
Food: Corn
Limiting AA in Food: Tryptophan, lysine
Complementary Foods: Legumes
15
Q
Amino Acid Combining frequency
A
- Do plant foods always need combining in one meal?
- It used to be thought that vegetarians and vegans need to combine different plant protein sources within the same meal. We now know that isn’t the case.
- So, whilst combining appropriate food sources in one meal is ideal, vegetarians and vegans just need to make sure they’re getting a range of plant protein sources throughout the day, as the amino acid pool is actually quite stable.
