Lecture 2: Macronutrients Flashcards
What are the macronutrients?
Proteins
Carbs
Fats
What is the kcal per macronutrient?
Carbs/proteins are 4 kcal/gram
Fats are 9 kcal/gram
What is a carb?
Organic compound made of carbon and water in a 1:1 ratio.
What do carbs lack?
No fatty acids
No amino acids
Where are carbs the majority of matter?
Plant matter
Why do we like carbs?
Readily usable energy. It is the primary source.
What % of calories are made up of carbs in a typical diet?
40-70%
What are the major functions of carbs?
Fuel for metabolic processes (ESP CNS, RBCs, and renal medulla)
Prevent protein breakdown for energy
Enable fat metabolism/oxidation
Taste/dietary variety
Healthy gut (our gut flora needs the fiber to eat)
Help form important cellular structures
What are the simple carbs?
Monosaccharides: glucose, fructose, galactose.
Disaccharides: sucrose, lactose, maltose
What is found in every simple carb?
Glucose.
What are the complex carbs?
Polysaccharides: Starches, cellulose, glycogen, gums, pectins
What are the primary starches in a human diet?
Amylose and amylopectin
What is glycogen?
Storage for glucose in ANIMALS.
What are the two types of fiber?
Soluble fiber, which dissolves in water and makes a gel-like material
Insoluble fiber, which stays intact and increases stool bulk.
What is fiber?
A resistant starch that is not absorbed or digested.
What is the recommended fiber intake?
30-38g for males
21-25g for females
Why do carbs need to be broken down?
Our body can only absorb monosaccharides in the GI tract.
How are carbs brokwn down?
Amylase from the salivary glands and pancreas.
Where are monosaccharides absorbed and moved?
Absorbed in the SI.
Moved to the liver.
Why do monosaccharides end up at the liver for processing?
It can covert all monosaccharides to glucose.
It can convert excess glucose into glycogen to store.
It can covert excess glucose to TG/fats if glycogen is full.
Why are complex carbs better to eat?
Increased satiety due to the longer breakdown time.
What is the impact of fiber on blood sugar/energy?
None.
What is glycemic index?
Evaluates the 2-hour postprandial curve for BG values relative to a reference standard
What is glycemic load?
Similar to glycemic index, but it takes into account the standard serving size of the food.
What kind of pts can really benefit from a low GI/GL diet?
Chronic disease pts, esp. those with HTN, DM, cancer, CV disease, or obesity.
What is generally considered low GI?
Anything under 55, aka veggies, whole grains, low-fat stuff.
What is the recommend carb intake in terms of %?
45-65% of carbs.
What are the clinical pearls for pt education regarding carbs?
Less processed is generally more healthy.
White foods are generally unhealthier.
Fiber is your friend.
Avoid eating carbs without protein or fat.
Type of carb is more important than the amt.
Avoid sugary beverages
What are dietary fats?
Water-insoluble lipids.
Where do dietary fats come from?
Plants AND animals
What essential thing do dietary fats contain?
Essential amino acids.
What countries have high dietary fat intake?
Some european countries and the US.
Why is consuming excess fat so easy to do?
It has a low satiety index.
It feels less filling but has the highest calorie/gram.
What are the major functions of dietary fats?
Energy reserve
Adipose tissue (you can store extremely high amts of kcal in adipose tissue)
Absorb necessary fat-soluble vitamins (DEAK)
Provide the essential AAs (linoleic and alpha-linoleic acid)
Component of body structures and molecules
Insulate
Cushioning
Flavor
What are saturated fats more likely to be at room temp?
Solid.
What is a saturated fat?
Max # of carbon-hydrogen bonds, aka no double bonds.
Where do saturated fats come from?
Coconut oil, palm oil
Animal meats
Dairy
Processed meats
Pre-packaged snacks
What are unsaturated fats?
Fats with at least 1 double bond.
What are the monounsaturated fats?
Olive, canola, peanut, avocado oils
What are the polyunsaturated fats?
Omega-3 and omega-6 FAs.
Walnut, sunflower, flax, soybean, fatty fish
What are unsaturated fats more likely to be at room temp?
Liquid
Where do unsaturated fats mostly come from?
Plants
What is healthier overall, saturated or unsaturated fats?
Unsaturated fats.
What are trans fats?
Modified unsaturated fats with altered double bonds.
How are trans fats often made? Why are they used?
Hydrogenation, aka heating liquid veggie oils in the presence of H gas.
This convert oils to solid forms like margarine.
They are incredible stable, long shelf-lives, and cheap to make.
They can also resist repeated heating.
Why are trans fats bad?
Associated with negative health outcomes.
It causes a higher LDL, lower HGL, pro-inflammatory, and insulin resistance
Where are trans fats commonly found?
PROCESSED FOOTS
How are fats broken down?
TGs are broken down into FAs by lipase.
How are FAs broken down?
Bile salts are added in the duodenum to FAs.
Where do short and medium chain FAs get absorbed?
Upper small bowel.
Where do long-chain FAs and cholesterol get absorbed?
Converted back into TG to be transported in lymph as chylomicrons.
Where are bile salts reabsorbed?
Lower small bowel.
What organ processes and packages fats?
Liver.
Why should you not give infants cow’s milk prior to 1 y/o?
They don’t have lipase to break down the fat. Only human milk contains lipase.
What happens in people as their ability to absorb fat goes down?
Less fat absorption
Less adipose tissue
Difficult to absorb the fat-soluble vitamins! (DEAK)
What kind of pts can get fat malabsorption syndromes?
Gastric resections
Inflammatory bowel disease
Enzyme deficiencies
What is the recommendary caloric intake for dfats?
20-35%
aka 44-78g/day.
What are the clinical pearls for pt education regarding fats?
Less processed = more healthy
Avoid eating carbs in place of fat
Type of fat matters more than amt
PUFAs are best!!!
Elimination of dietary fat is not as good as just having a well-balanced diet.
What are proteins?
Organic compounds made of carbon, water, and NITROGEN
Where are proteins found?
Every tissue, 50% stored in skeletal muscles.
What is the satiety index of proteins?
Highest!
Very filling calorie for calorie
What are the major functions of proteins?
Synthesis of structural and functional proteins.
Structural: keratin, collagen, myosin
Functional: enzymes and hormones
May be used for energy
Metabolic demands!!!
What are some common states that cause increased metabolic demand?
Growing children
Pregnancy
Recent surgery
Muscle building
What are the animal-based protein sources?
Meat, fish, crustaceans, dairy, eggs, proteins shakes
What are the plant-based protein sources?
Nuts, beans, peas, seeds, tofu, lentils, chickpeas
What protein is better?
Animal-based.
They are more easily digestible and align more closely with human needs.
What are the pros and cons of plant-based diets?
Pros:
Can still meet every protein need with less environmental impact and reduced risk of some disease.
Cons:
Lower in some essential nutrients, must be well-balanced, and cooking method is very important.
What are the 3 types of amino acids in protein?
Essential amino acids, which we must get from food.
Semi-essential, which are normally endogenous but can be compromised.
Non-essential, which are always endogenous.
What starts the initial breakdown of protein?
Pepsin from the stomach lining.
What is the next step of protein breakdown after the stomach?
Proteases from the pancreas and SI, aka trypsinogen and chymotrypsinogen.
Where are AAs absorbed?
SI, which then sends them to the liver for resynthesis and redistribution.
Why is AA storage limied?
If not needed for protein synthesis, they get metabolized to glucose.
What is the recommended intake of protein?
10-35% but varies heavily with age, health, and physical activity.
What kind of patients need to be careful with protein intake?
Kidney or liver disease. They must decrease their overall protein intake.
What are clinical pearls for pt education regarding protein?
All protein comes as a package, aka calories/fiber/sodium/etc.
Found in both animal and plants (variety)
Overconsumption can cause health problems in the long term.
Protein needs vary greatly among pts.
What is rabbit starvation?
Eating excessively lean meat, resulting in little fat and way too much protein.
What are some common intolerances that result in a lack of carb absorption?
Lactose intolerance
Gluten intolerance/celiac disease
What is the most common complaint regarding failure to absorb carbs?
GI upset, aka bloating because bacteria are fermented the unabsorbed/digested carbs.
What are common symptoms regarding carb malabsorption?
Abd pain
Cramping
Flatulence
Bloating
Altered bowel habits
What kind of patients typically have fat malabsorption?
Those with GI illnesses!
Chronic inflammation
Resection of stomach or intestine
Pancreatic disease
What is the most common symptom of fat malabsorption?
Greasy diarrhea.
What is steatorrhea?
Fatty stools; foul-smelling, light-colored, floating stools.
What deficiencies can occur as a result of fat malabsorption?
D: thinning bones, fatigue, muscle aches/weakness, depression
E: impaired reflexes/coordination, difficulty walking, muscle weakness
A: vision and skin changes
K: nosebleeds, bleeding gums, prolonged bleeding time, GI hemorrhage
What is a deficiency in protein and other general nutrients called?
Marasmus. Results in profound muscle wasting and emanciation.
What is a deficiency in protein alone called?
Kwashiorkor. Results in edema and rotund bellies. Often seen in 3rd world countries with poor access to protein.
What kind of patients often have poor protein intake/absorption?
Prolonged fasting, liquid diets, limited oral intake, TPN, or chronic liver disease, or CKD.
Why can patients with CKD have a lack of protein in the body even if they eat enough?
Protein loss in the urine > consumption
What are the symptoms of a protein deficiency?
Low Hb, low serum albumin, impaired immune function
