Protein and Amino Acids

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Protein and Amino Acids

• Leo Galland, M.D., F.A.C.P., F.A.C.N.
• Foundation for Integrated Medicine

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How much protein does a person really need? Does
the source of protein matter?

• __________________________________
• Few issues in nutritional science have aroused
  such long-standing and deep-seated controversies
  as protein and amino acid requirements.
• Millward, J Nutr 1997

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The Elements of Life

• Carbon
• Oxygen
• Hydrogen
• Nitrogen
• Sulfur
• Phosphorus
• Minerals Ca, Mg, Na, K, Fe, Zn, Cu, Se, Mn,
  Cr, Mo, Vn, Ni...

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Essential Amino Acids

• Isoleucine
• Leucine
• Lysine
• Methionine
• Phenylalanine
• Threonine
• Tryptophan
• Valine
• Arginine
• Histidine

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Major Non-essential Amino Acids

• Alanine
• Asparagine
• Aspartate
• Cysteine
• Glutamate
• Glutamine
• Glycine
• Proline
• Serine
• Tyrosine

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The Fate of Dietary Protein

• Digestion and absorption (efficiency varies by
  25, depending upon protein source)
• Maintenance of body protein stores
• Net protein synthesis (less than 10 of minimum
  requirements, even in children)
• Synthesis of non-protein compounds
• Oxidative deamination

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Essential Non-Protein Nitrogen-Requiring
Processes

• Nucleic acid synthesis, including adenosine for
  ATP (glutamate, aspartate, glycine, glutamine)
• Nervous system Neurotransmitter/neuropeptide
  synthesis (phenylalanine, tryptophan,
  glutamate.)
• Immune system Cytokine production,Anti-oxidant
  protection (taurine glutathione cysteine,
  glutamate, glycine)
• Skeletal muscle Creatine (methionine, arginine,
  glycine)
• Cardiovascular system Nitric oxide synthesis
  (arginine)
• GI tract Mucin secretion (threonine, cysteine,
  serine, proline)

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How dietary protein is recorded

• grams/day 50-135
• mg/kg body weight 800-1500
• of kcalories consumed 10-20

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Minimum Protein Requirements

• Obligatory Nitrogen Loss (metabolic ward)
• 36 mg/kg/day urinary (85)
• 12 mg/kg.day fecal (13)
• 8 mg/kg/day sweat, skin, saliva, hair (2)
• 54 mg of nitrogen/kg/day total
• Replacement requires 340 mg protein/kg/day
• 70 kg person 24 gm/day
• WHO safe minimum 750 mg/kg/day, of which 84
  mg/kg should be essential amino acids
• 70 kg person 52 gm/day
• 60 kg person 46 gm/day

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Minimum Safe Protein Requirements for Children

• Newborns 1.85 mg/kg/day
• Infants 1.5-1.65 gm/kg/day
• Toddlers 1.1-1.2 mg/kg/day
• School children 1.0 mg/kg/day
• Adolescents 0.9-0.95 mg/kg/day
• N-balance depends upon caloric intake. Fewer
  calories increase protein needs. Profound
  inter-individual differences

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US Adult Protein RDA's

• female male
• Calories 1900-2200 2300-2900
• Protein 46 gm 71 gm
• about 10 of calories
• typical US diet 15 of calories
• popular weight loss diets 30 of calories
• excess protein is oxidized by deamination

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Ketogenic Amino Acids

• Exclusively ketogenic
• Leucine
• Lysine
• Ketogenic and glucogenic
• Threonine
• Isoleucine
• Phenylalanine
• Tyrosine
• Tryptophan

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Hunter-Gatherer Diets

• Compared to typical U.S. diet
• high dietary protein (19-35 of calories)
• relatively low level of dietary carbohydrate
  (22-40 of calories)
• variable fat intake (28-58 of calories)

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The paradoxical nature of hunter-gatherer diets
meat-based, yet non-atherogenic L Cordain, S B
Eaton, et al Eur J Clin Nutr 2002 56, Suppl 1,
S42-S52

• 13 known quantitative dietary studies of HG
  demonstrate that animal food provided the
  dominant (65) energy source, while gathered
  plant foods comprised the remainder (35).
• Comprehensive review of 229 HG societies mean
  subsistence dependence upon gathered plant foods
  was 32, whereas it was 68 for animal foods.

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Changes in nutritional status and patterns of
morbidity among free-living elderly persons a
10-year study. Vellas et al, Nutr 1997 13
515-9

• 304 healthy French elderly (median age 72 in
  1980) 97 (34.2) remained healthy74 (26.5)
  became frail or sick 54 (19.1) died, 57 (20.1)
  dropped out. Median protein intake was 0.8-1.2
  g/kg of body weight in 1980-81.
• Protein intake 1.20-1.76 g/kg associated with
  fewer health problems over the next 10 years vs
  protein intakes lt 0.8 g/kg

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High-protein low fat diets are effective for
weight loss and favorably affect biomarkers in
healthy adults. Johnson et al. J Nutr 2003 134
586-91. 2003

• 20 adults, low fat (lt30 kcal) diets, consuming
  either 10 or 30 protein
• Weight loss (-6 over 6 weeks) and fat loss (-9
  to -11) not affected by protein
• Cholesterol (-10 to -12), insulin (-25), uric
  acid (-22 to -30) similar changes
• Hunger and satiety better with high protein
• Ca-balance unaffected, N-balance better

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A Reduced Ratio of Dietary Carbohydrate to
Protein Improves Body Composition and Blood Lipid
Profiles during Weight Loss in Adult Women.
Layman DK. J.Nutr. 2003 133411-417

• 24 women age 45 to 56, BMI gt26 kg/m2
• Isocaloric, matched-fat diets, 68 vs 125 g
  protein/day for 10 weeks.
• HP loss of fat/lean (6.3 1.2 g/g) vs LP (3.8
  0.9).
• Cholesterol down 10 for both, TGs down only for
  HP (21)
• LP had higher insulin responses to meals and
  postprandial hypoglycemia
• HP reported greater satiety.
• Increasing the proportion of protein to CHO in
  the diet of adult women has positive effects on
  body composition, blood lipids, glucose
  homeostasis and satiety during weight loss.

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Randomized trial on protein vs carbohydrate in ad
libitum fat reduced diet for the treatment of
obesity. Skov et al. Int J Obes 1999 50418-30

• 50 subjects, protein of 12 vs 25 of kcal, mean
  BMI of 30.8 and 30.0.
• 27 week weight loss high protein 8.9 kg, high
  CHO 5.1 kg
• 27 week fat loss high protein 7.6 kg, high CHO
  4.3 kg (84-85 of total weight loss)
• Kcal consumed 2139 high protein vs 2605 high CHO.

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Dietary protein and risk of ischemic heart
disease in women. Hu et al, Amer J Clin Nutr,
1999. 70 221-7

• 80,082 women aged 3459 y
• Median protein 14.7 of kcal to 24.0 of kcal by
  quintile. Higher protein associated with less
  tobacco and alcohol use, more exercise and
  multivitamin and vit E supplements, more fat,
  saturated fat, cholesterol, folate, meat, dark
  bread, fruits and vegetables, and less
  carbohydrate (white bread, potatoes, sweets and
  desserts.)
• High protein intakes reduced risk of ischemic
  heart disease RR 0.74 (95). Both animal and
  vegetable protein contributed to the lower risk,
  but most of the protein came from animal sources.
  This inverse association was similar in women
  with low- or high-fat diets.
• Conclusion Increased dietary protein does not
  increase and may reduce risk of ischemic heart
  disease.

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Short-term effects of substituting protein for
carbohydrate in the diets of moderately
hypercholesterolemic human subjects. Wolfe BM,
Giovannetti PM. Metabolism 1991 Apr40(4)338-43.

• Hypercholesterolemic human subjects (four men,
  six women)
• Diets 23 v 11 of energy as protein, 24 as
  fat, 53 v 65 as carbohydrate. Isocaloric
  substitution of protein for CHO during low fat
  diet
• High protein HDL-C higher by 12 (plt.01),
  total cholesterol (TC) lower by 6.5 (plt .001),
  LDL-C lower by 6.4 (plt.02), TG lower by 23
  (plt.02). LDL-C/HDL-C lower by 17 (plt.001).

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Cardiovascular Disease and Diabetes Inverse
relationship between urinary markers of animal
protein intake and blood pressure in Chinese
results from the WHO Cardiovascular Diseases and
Alimentary Comparison (CARDIAC) Study.Liua L et
al, Int J Epidemiology 200231227-233

• Urinary 3-methylhistidine (3MH) excretion (a
  biological marker of animal protein intake) and
  BP in 11 Chinese population samples
• 3MH and 3MH/creatinine were inversely associated
  with BP and hypertension, even after adjustment
  for age, sex, Na/K ratio, BMI, calcium and
  magnesium.
• The results provide strong evidence that animal
  protein intake is associated inversely with BP in
  Chinese populations.

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Impact of diet on blood pressure and age-related
changes in blood pressure in the US population.
Hajjar et al. Arch Intern Med. 2001161589-93.

• All individuals gt20 yrs old (n 17,030) surveyed
  in NHANES III
• Systolic BP and pulse pressure positively
  associated with higher Na, alcohol, and protein
  intakes (Plt.05)
• Age-related increase in systolic BP was
  attenuated by higher Ca and protein intakes.

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An increase in dietary protein improves blood
glucose response in persons with type 2 diabetes.
Gannon et al. Am J Clin Nutr 78 734-41.

• 10 men, 2 women, age 39-72, BMI 22-37
• 2250 kcal 55 CHO, 15 protein, 30 fat vs 40
  CHO, 30 protein, 30 fat
• Glycemic response to high protein diet (AUC) was
  40 lower.
• Glycated Hb decreased 0.8 at 30 protein vs 0.3
  (plt.05) over 5 weeks.

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Meat and dairy food consumption and breast
cancer a pooled analysis of cohort studies.
Missmera et al. Int J Epidemiol 20023178-85

• Eight prospective cohort studies 351 041 women,
  7379 diagnosed with invasive breast cancer during
  15 years of follow-up.
• No significant association between intakes of
  total meat, red meat, white meat, total dairy
  fluids, or total dairy solids and breast cancer
  risk.
• J-shaped association for egg consumption where,
  compared to women who did not eat eggs, breast
  cancer risk was slightly decreased among women
  who consumed lt2 eggs per week but slightly
  increased among women who consumed 1 egg per day.

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Dietary factors and the survival of women with
breast carcinoma. Holmes MD, et al. Cancer
199986826-35

• 1,982 female registered nurses with breast cancer
  diagnosed between 1976-1990 who completed a food
  frequency questionnaire.
• The main outcome measure was time to death from
  any cause.
• The relative risk (95 confidence interval) of
  mortality comparing highest with lowest quintile
  of protein intake was 0.65 (0.47-0.88).

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Meat, cancer and dietary advice to the public.
Hill, Eur J Clin Nutr 200256 Suppl 1S36-41

• Epidemiological data are consistent with a
• protective role for fruit, vegetables and whole
  grain cereals in colon cancer with no role for
  meat consumption as a risk factor.
• Meat may play a protective role in gastric
  cancer.
• Data from Europe are not consistent with those
  from the US because of the different contexts
  (meal composition) within which meat is consumed
  in different countries

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Meat consumption and colorectal cancer a review
of epidemiologic evidence. Noral Riboli,
Nutrition Reviews 200159 37-47

• Review of 36 studies, most show no significant
  effect for any kind of meat
• Relative risk ranged from 0.41-2.87
• Studies with significant adverse association
• RR 1.33-2.87 for total meat in 5/32 studies
• RR 1.04-2.35 for red meat in 8/26 studies
• RR 1.18-2.87 for processed meat in 13/32 studies

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Protein consumption and bone mineral density in
the elderly the Rancho Bernardo Study.
Promislow et al. Am J Epidemiol 2002155636-44

• 572 women and 388 men aged 55-92 years.
• Positive association between animal protein
  consumption, assessed by FFQs in 1988-1992, and
  BMD measured 4 years later.
• Negative association between vegetable protein
  and BMD was observed in both sexes.
• Increasing protein consumption appearing to be
  more beneficial for women with lower calcium
  intakes, but evidence for this interaction was
  not consistently strong.

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Effect of Protein Intake on Bone Mineralization
during Weight Loss A 6-Month Trial. Skov et al.
Obesity Research 10432-8 (2002)

• 65 overweight adults, 6-month of high protein
  (HP 107.8 g/d)vs low protein (LP 70.4 g/d)
  matched fat diets.
• BMC loss, adjusted for differences in fat loss,
  was greater in the LP group than in the HP group
  difference in LP vs. HP, 44.8 g (95 confidence
  interval, 16 to 73.8 g) p lt 0.05.
• Independent of change in body weight and
  composition during the intervention, high protein
  intake was associated with a diminished loss of
  BMC (p lt 0.01).

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Protein supplements increase serum IGF-1 levels
and attenuate proximal femur bone loss in
patients with recent hip fracture. Schurch et
al. Ann Int med 1998 128 801-9.

• 82 patients, mean age 80 years, mean dietary
  protein 45-51 g/day, recent femoral fracture, vit
  D3 200,000 IU given
• Supplement 250 kcal, 20 g protein/35 gm CHO/3 g
  fat vs 54 g CHO, Ca/Mg/P/A/K1
• Protein improved femoral healing at 1 y,
  increased IGF-1 and pre-albumen

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A high dairy protein, high-calcium diet minimizes
bone turnover in overweight adults during weight
loss. Bowen et al. J Nutr 2004 134 568-573

• 60 subjects (BMI 27-40) lost mean of 9.7 kg over
  12 weeks on diets of 34 protein, 41 CHO, 24
  fat
• Diet 1 dairy-based, 2400 mg Ca/day. Diet 2,
  meat-based 500 mg Ca/day
• Bone resorption markers increased more with
  meat-based diet and osteocalcin increased only
  with meat-based diet

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Meta-analysis of the effects of soy protein
intake on serum lipids.Anderson et al NEJM.
1995333276-82

• Meta-analysis of 38 controlled clinical trials
• Soy protein intake averaged 47 g/day.
• Compared with animal protein, soy effect
• Total-C decreased 23.2 mg/dl (9.3, plt.05)
• LDL-C decreased 21.7 mg/dl (12.9 , plt.05)
• TG decreased 13.3 mg/dl (10.5 , plt0.05)
• HDL-C increased 2.4 (NS).
• TC and LDL-C Changes directly related to the
  initial serum cholesterol (P lt 0.001)

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A Dietary Portfolio Approach to Cholesterol
Reduction. Jenkins et al. Metabolism 2002 51
1596-1604

• 7 men, 6 women age 43-84, BMI 21-31, on diets low
  in saturated fat and cholesterol
• Per 1000 kcal
• Soy protein 22.7 g
• Viscous fiber 8.2 g (oats, barley, psyllium,
  okra, eggplant)
• Plant sterols 1 g (margarine)
• Raw unblanched almonds 2.9 g
• LDL-C decreased 29 (plt.001), LDL/HDL decreased
  26.5 (plt.001)

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Legume consumption and risk of coronary heart
disease in US men and women. Bazzano et al. Arch
Intern Med. 20011612573-8

• 9632 men and women who participated in NHANES 1
  and were free of CVD
• Frequency of legume intake was estimated using a
  3-month food frequency questionnaire,
• 19 years of follow-up, 1802 incident cases of CHD
  and 3680 incident cases of CVD were documented.
• Legume consumption was significantly and
  inversely associated with risk of CHD (P .002
  for trend) and CVD (P .02 for trend) after
  adjustment for established CVD risk factors.
• Legume consumption 4 times or more per week
  compared with less than once a week was
  associated with a 22 lower risk of CHD (relative
  risk, 0.78 95 confidence interval, 0.68-0.90)
  and an 11 lower risk of CVD (relative risk,
  0.89 95 confidence interval, 0.80-0.98).

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The Impact of protein on renal function decline
in women with normal renal function or mild renal
insufficiency.Knight et al, Ann Int med 2003
138 460-7

• 1624 nurses age 42-68, followed for 11 years,
  protein intake measured by FFQ (mean 76 g/d)
• GFR estimated from serum creatinine, age, height,
  weight by 2 formulas
• No effect of protein on GFR in women with
  baseline GFRgt80 ml/min/1.73 m-squared.
• Initial GFR of 55-80 ml/min (S-creatinine
  .77-1.1mg/dl, mean .88) showed a decline in GFR
  of 7.72 ml/min/10 g increase in protein. Meat
  proteingtdairy protein. No effect of vegetable
  protein.

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Purine-Rich foods, Dairy and Protein Intake, and
the Risk of Gout in Men. Choi et al, NEJM 2004
350 1093-1103

• 47,150 men followed for 12 years
• Incidence of gout increased with increasing
  intake of protein from meat or seafood and
  decreased with increasing intake of dairy
  protein. No effect of total protein
• Relative risk
• 1.41 for 2.5 vs 0.5 meat servings/day
• 1.51 for 0.8 vs 0.04 seafood servings/day
• 0.56 for 4.2 vs 0.5 dairy servings/day

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Protein Consumption May Affect Mineral
Bioavailability

• High meat diets increase zinc bioavailability in
  elderly women (Hunt et al, Am J Clin Nutr 1995
  62 621-32) and iron and zinc utilization in
  young women, with no effect above 3 oz lean
  beef/d. (Johnson Walker, J Am Diet Assoc 1992
  92 1474-8).
• Replacement of 25 meat protein by soy protein
  decreased zinc absorption and protein
  digestibility (Sandstrom et al, J Nutr 1986 116
  2209-18)

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Large Neutral Amino Acids Share Common
Transporters

• The ratio of tryptophan to leucine, isoleucine,
  valine, phenylalanine and tyrosine (5LNAA)
  influences brain serotonin concentration
• Exercise and CHO loading raise this ratio
• High protein diets lower this ratio
• Control of brain serotonin by the diet. Wurtman
  RJ, Fernstrom JD. Adv Neurol 1974519-29

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Implications of Competitive Transport of LNAA
into Brain

• Tryptophan/5LNAA is lower in major depression,
  correlates with severity of depression and with
  plasma cortisol level following dexamethasone
  suppression.
• Tryptophan/5LNAA is higher after strenuous
  exercise and in patients with fibromyalgia,
  correlates with intensity of post-exertional
  fatigue, reversible with BCAA feeding

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References on LNAA Transport

• Decreased plasma tryptophan concentration in
  major depression relationship to melancholia and
  weight loss. Anderson IM, et al. J Affect Disord
  199020185-91
• Relationship between the dexamethasone
  suppression test and the L-tryptophan/competing
  amino acids ratio in depression. Maes M, et al.
  Psychiatry Res 198721323-35
• Plasma tryptophan and five other amino acids in
  depressed and normal subjects. DeMyer MK, et al
  Arch Gen Psychiatry 198138642-6
• Serotonergic markers and lowered plasma
  branched-chain-amino acid concentrations in
  fibromyalgia. Maes M, et al Psychiatry Res 2000
  49711-20.
• Amino acids and central fatigue. Blomstrand E.
  Amino Acids 200120(1)25-34

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Glutathione (GSH) Levels Depend Upon Dietary
Sulfur Amino Acids

• GSH/GSSG is the major human redox pair
• Malnutrition, fasting and alcoholism deplete
  hepatic and WBC GSH levels
• Depletion of GSH impairs immune function and
  detoxification of substrates like acetaminophen
• Loading with sulfur AA reverses these effects

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Conclusions

• High protein intake (up 30 of kcal) is not
  detrimental and may produce improved health
  outcomes.
• Dairy and vegetable protein may have different
  effects than meat protein.
• Elderly patients often consume too little protein
  and should be encouraged to increase intake to gt1
  gm/kg/day (pulse feeding of 0.8 g/kg at one meal
  may work best Arnal et al, Am J Clin Nutr 1999
  69 1202-8)