Nutrition Chapter 5
Weight
If you are overweight and lose weight, your LDL will decrease and your HDL will increase, but your HDL will increase only if you lose sufficient weight to approach the normal weight range. If you gain weight, the opposite occurs. Dietary changes cannot approach effects on HDL that can be obtained through exercise and weight control.
Cholesterol
in the blood mostly determined by dietary fat, and dietary cholesterol. Official recommended limit of 300 mg/day. (= 1.5 eggs per day) - Not important for most people. (A committee has recommended abolishing a cholesterol limit.)
Triglycerides
Fat tissue and fat in food is primarily in the form of
Omega-3 fatty acid benefits
Omega-3's (DHA in particular) participate in the development of brain function Particularly frontal lobe - responsible for complex reasoning and problem solving)
A triglyceride consists of
One glycerol backbone molecule Three fatty acid molecules, esterified to the glycerol
The PCSK9 Gene
Over-expression of PCSK9 results in a marked reduction in LDL cholesterol receptors in the liver and inefficient removal of LDL cholesterol. People with this have high LDL cholesterol levels. Under-expression of PCSK9 results in high levels of LDL cholesterol receptors and efficient removal of LDL cholesterol. People with this (most commonly seen in people of African heritage) have low LDL cholesterol levels.
Saturated Fatty Acids
Stearic acid (named from stears!) - C18 Palmitic acid (named from palm trees) - C16
Fish vs. Vegetable Omega-3's
Two omega-3 fatty acids are of great benefit in relation to heart and brain health: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). These are supplied directly by fish, but not by vegetable sources of omega-3 fatty acids. Vegetable sources supply omega-3 fatty acids in the form of alpha-linolenic acid, which can be converted in the human body to EPA and DHA. However this conversion is inefficient, and fish is the preferred source of omega-3 fatty acids. But walnuts help prevent heart attacks - both animal and vegetable forms are good.
Trans Fatty Acids
Very little natural--processed foods, fries
Fat cells have...?
Very little water and require little energy for maintenance--efficient way to store energy
Diet and LDL Cholesterol
Walnuts (8/day) Reduces LDL 20% Soluble Fiber Reduces LDL 1-10% (Oatbran, fruit, vegetables) Soy protein (20-30 g/day) Reduces LDL 5-7% Stanol esters (1½-4 g) Reduces LDL 10-15% Flaxseed meal (1-5 tbs) Reduces LDL ~18% Policosanols Reduces LDL 19-31% Raises HDL 8-19%Krill oil (2 g/day) Decreases LDL 37% Increases HDL 55% New result - needs independent confirmation, as well as safety evaluation. The reported effect is enormous! This result may be due to the fact that in krill oil, most omega-3's are in the form of phospholipids, not triglycerides
What's wrong with high levels of omega-6 fatty acids?
We don't need as much Omega-6 as we are ingestingpolyunsaturated fatty acids are oxidized more easily. But foods rich in polyunsaturated fatty acids are rich in antioxidant chemicals, so it all evens out! There is no evidence whatsoever that high levels of omega-6 fatty acids are unhealthy.
2012 Addition
What addition are new studies are questioning whether HDL levels really matter? A scientist looked at 14 common genetic variants that result in lower HDL levels without affecting LDL levels. In each case, the risk of heart attack was the same in people that had the low-HDL variant as in people with the high-HDL variant. When he looked at common genetic variants affecting LDL, he found that they did make a difference.
Nutrigenetics-for ordinary people
Your genetic constitution for several genes is checked by DNA analysis. The company then makes nutritional recommendations that is right for your genotype. Salugen charges $424.95 for the DNA test, then a monthly fee of $99.95 for dietary supplements. My assessment: Too early. Only a handful of genes are checked, and no good data exists on whether the diets are effective.
Omega-3's and mental processing
A Norwegian study showed that children born to mothers who received cod liver oil during pregnancy and lactation scored 4 points higher on a mental processing test at age 4 than children born mothers who received corn oil. (Recall the Winston Churchill, during WW II, wanted women to receive cod liver oil.)
Is fat bad for you?
A great deal of animal fat - animal fat is high in saturated fatty acids, and is not good. But unsaturated fat is fine, and omega-3 fatty acids are particularly good.
Harsh US Gov't assessments of nutrigenetics
"Nutrigenetic tests are at best ambiguous and at worst dangerous." US government Office of Accountability (GAO) "Some nutrigenetic tests are tantamount to 'genetic horoscopes'." Thomas Hamilton, director of survey and certification group at the Center for Medicaid and State Operations of the US government.
Lipoproteins
Chylomicrons (transport fat from intestines to liver after eating) VLDL and LDL = Bad cholesterol - transport fat from liver to adipose tissue for storage. HDL = Good cholesterol - transport fat from adipose tissue to muscles to be "burned" for energy. VLDL = Very Low Density Lipoprotein LDL = Low Density Lipoprotein HDL = High Density Lipoprotein
The McAuley-Mann Diet
A scientific diet to reduce the development of insulin resistance. Largely plant-based diet with low saturated fat and high fiber. Similar to the Willett diet, except that Willett recommends a higher fat content and a high omega-3 fat content. This is because omega-3's are not associated with protection from insulin resistance.
Where is fat stored?
Adipose tissue
Special role of DHA in brain function
DHA is sucked up into the nervous system from the general circulation and avidly retained there. DHA is found in especially high concentrations in the eye. It is vital for structure of nerve cells and is found in high amounts in the synapses that control transmission of electrical signals by the nervous system. Although DHA will not prevent Alzheimer's disease and other forms of cognitive decline, it will slow the progress of the disease. DHA is also active in slowing the progression of nervous system damage in Parkinson's disease. DHA also helps prevent macular degeneration, the most common cause of blindness in industrialized countries.ALA from vegetables sources, although not efficiently converted to DHA, still results in sufficient DHA in the nervous system to achieve these benefits.Our caveman ancestors almost certainly had high dietary DHA even when they didn't eat fish. Grass-fed beef is high in omega-3 polyunsaturated fatty acids, including DHA. The problem with commercial beef is that cattle are fattened on feed lots with corn, and corn contains almost no omega-3 fatty acids.
Fatty acids are classified by
Degree of saturation Length of chain
Diet and your genes
Diet and genes can be critically important. Men with hypercholesterolemia (a rare inherited high blood cholesterol) die of heart attacks at an average age of 45. Four ancestral men born before 1880 lived to 62, 68, 72, and 81 years. Why such a difference? - Probably due to saturated fat in our modern diets.
Diet and Cholesterol
Especially bad for raising LDL cholesterol - saturated fat.
Policosanols
From purified sugar cane wax. Sold under trade name of Ateromixol. Better safety than statin drugs (no liver damage) and greater effects with lower doses. Inhibit lipid oxidation. Only food substance (besides krill oil) that has an effect on HDL cholesterol comparable to exercise. Has not been subject to exhaustive testing
What determines LDL vs HDl
Genetics. Epsilon-2 is correlated with a high HDL, low LDL Epsilon-4 is correlated with a low HDL, high LDL, and Alzheimer's disease. Epsilon-4 protects from detrimental effects of repeated diarrheal infections on educational performance. Epsilon-3 is intermediate between 2 and 4.
Recommendations for Omega-3
Have fish, especially fatty fish two or three time per week. Wild salmon and sardines are high in omega-3 fatty acids and low in mercury. Have ¼ cup of walnuts per day as a snack or in salads or other foods. Use olive oil and canola oil for cooking and baking, and use walnut oil and olive oil in salad dressings. Add omega-3 fatty acid supplements at a dose of 1 to 3 g/day. (This is equivalent to 1 to 3 teaspoons of cod liver oil.) Limit intake of saturated fat by decreasing portion sizes of meat and using reduced-fat dairy products.
Omega-3's and Triglycerides
High plasma lipid levels has the technical name "hypertriglyceridemia". Hypertriglyceridemia following ingestion of meals is a significant risk factor for heart disease This is lowered by polyunsaturated fatty acids, particularly omega-3 fatty acids.
Serum triglycerides
If you increase the fat content of your diet, serum triglycerides will decrease. If you increase the carbohydrate content of your diet, serum triglycerides will increase. Free sugars are especially a problem in people who are insulin resistant. The fat benefit is especially high if the fat is low in saturated fat and high in unsaturated fats.
Flaxseed Oil
In addition to its substantial effects on lowering LDL cholesterol BLANK is reported to improve symptoms of kids with ADHD* (Attention Deficit Hyperactivity Disorder), and to reduce the severity of the autoimmune disease lupus (also called SLE, for systemic lupus erythematosis).
Omega 3's Effect on Immune system
Increase the immune response to disease. Decrease unwanted actions of the immune system, including the following: Causes reduction the rate of progression, severity, or relapse of lupus, rheumatoid arthritis, other autoimmune disorders decrease and the severity of inflammatory bowel diseases such as Crohn's disease.
Exercise
Increases HDL as nothing else can. (Alcohol - 1 drink per day for females and two for males - but effect is small compared to the effect of exercise. Higher amounts of alcohol do not help and may cause liver disease, alcohol dependence and other problems.) Does not affect LDL
Smoking
Increases LDL and decreases HDL
Can you change your cholesterol through diet?
Individual experiences are variable. The average reduction of LDL cholesterol is about 10-15% (equivalent to a 25-35% reduction in the rate of heart attacks). Most successful are those who started with high levels, lose weight (and started overweight), are young, implement more restricted diets, and have right genetics.
Benefits of Omega-3 Fatty Acids
Lowering of triglyceride levels in blood. Improvement of immune function. Improvement of brain function. Reduce chronic stress. Students showed decreased aggressive behavior during exams and decreased production of stress-induced pro-inflammatory hormones. Reverse effects of chronic stress on learning and memory. Reduce the risk of developing schizophrenia
Does it matter what we eat?
Muslims who observe the month of Ramadan fast a good portion of each day. During Ramadan their LDL levels decrease and their HDL levels increase. This may be a result of the frequency of eating (fasting between dawn and dusk), and eating less (a 2008 male student postponed his diet analysis to October because he was coming in under 1,000 calories/day in his September month of Ramadan).
Monounsaturated Fatty Acids
Oleic acid (think of oleo margarine) - C18 Palmitoleic acid - C16
Olibra
Olibra is a 95:5 mixture of fractionated palm oil and fractionated oat oil, which can be incorporated into yogurt in the form of an emulsion. Olibra resists digestion, and it promotes satiety by slowing emptying from the stomach. Olibra has a strong inhibitory effect on the appetite, which lasts throughout the day.
Monounsaturated Fatty Acids
Olive oil is very high in monounsaturated fat. Unsaturated fat of any kind is healthy fat - whereas saturated fat is very bad for people with heart disease or poor cholesterol profiles (we discuss later). Monounsaturated fat is not oxidized as easily as polyunsaturated fat, and is therefore very healthy.
The Willett Diet
Promoted by a Harvard scientist who has examined many epidemiologic studies on diet and heart health. His diet is 40% fat. Promotes whole grain carbohydrates over refined grains Limit white bread and pasta. Promotes unsaturated (vegetable) fats, and not saturated (animal) fat. Promotes a diet high in fruits, vegetables, nuts, and whole grains. Promotes high protein diet, with protein derived principally from nuts, soybeans, legumes, poultry, fish
Omega-6 Polyunsaturated fatty acids
Prototype is linoleic acid-predominant in vegetable sources-Control relaxation/contraction of muscles Control opening/constriction of blood vessels Promote inflammatory response to injury and infection. - Key element of body's defenses. Aspirin slows actions initiated by omega-6 fatty acids.
Omega-3 Polyunsaturated fatty acids
Prototype is linolenic acid In fish, canola oil and walnuts (& soybean oil) Coat platelets (a component of blood) and reduces their stickiness, and thereby reduces the likelihood if clot formation (and therefore the likelihood of a heart attack or stroke. Increase insulin signaling and decrease the risk of type 2 diabetes Reduce proliferation of colon, prostate, and breast cancers Reduce prevalence of lung disease.
NCEP Rec. for lowering LDL Cholesterol
Saturated fat to <7% 8-10% Trans fat to <2% Dietary cholesterol <200 mg 3-5% Add plant stanols/sterols to 2 g 6-10% Increase soluble fiber by 5-10 g 3-5% Lose 10 pounds 5-8% TOTAL 25-30%
Types of Fatty Acids are:
Saturated, Monounsaturated, polysaturated, trans
Fat Substitutes
Simpless Physically altered protein - 4 cal/g, and 1 g of Simpless replaces 3-4 g fat. 3.5 g fat x 9 calories/gram = 31.5 calories 1 g Simpless x 4 cal/g = 4 calories Olestra Not absorbed - zero calories. Really tastes like fat and survives baking. Vitamins not absorbed? Anal leakage?
Trans Fatty Acids
Structurally similar to saturated fat, and bad for heart health. Trans-fat is particularly bad for older, overweight people. As of January 1, 2006, trans-fat must be listed separately on food labels (formerly combined with polyunsaturated fat. Wendy's has eliminated trans-fat; others may follow.
The $1000 genome
The National Institutes of Health has a goal of sequencing BLANK, however we are not there yet. Even if your entire DNA sequence were known, in almost all cases you still would have no more information on how to eat for health. For example, if I knew your DNA sequence, I probably could not state your likelihood of developing diabetes.
Fat and weight control
The ability of high-fat feeding to promote satiety is rather low. This may be a function of the higher energy density of high-fat foods.Even prolonged vigorous exercise may not be sufficient prevent a positive energy balance if the fat intake is high. But medium chain-length fatty acids (in dairy products including butter) and polyunsaturated fatty acids have a relatively high satiety power. As compared to carbohydrate-rich breakfasts. . .Fat-rich breakfasts are followed by a higher intake of food during the morning, whereas. Carbohydrate-rich breakfasts can lead to a reduced appetite at lunchtime.