Chapter 3.doc

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10 Apr 2012
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Chapter 3 – Preconception Nutrition
Magnesium, Calcium, Vitamin D, and Vitamin B6 Supplements and PMS Symptoms
- Magnesium
oSupplements of 200mg per day given during 2 cycles are shown to decrease swelling, breast tenderness, and abdominal
bloating in PMS
o200 mg daily dose of Mg is below the Tolerable Upper Intake Level (UL), 350mg daily is considered safe
- Calcium and Vitamin D
oCalcium supplements of 1200mg per day for 3 cycles found to reduce PMS symptoms of irritability, depression,
anxiety, headaches, and cramps by 48%
oWomen with PMS found to have lower blood levels of Vitamin D and Calcium
oRisk of developing PMS 40% lower in women with average Vitamin D intakes of 706 IU (17.7 mcg) / day compared to
women consuming 112 IU (2.8 mcg)
oDaily Calcium intakes of 1238 mg were related to 30% risk reduction compared to women consuming 529 mg
oUL for Vitamin D for women is 50 mcg (2000 IU), and 2500 mg for Calcium
-Vitamin B6
oInvolved in synthesis of neurotransmitters such as serotonin that are related to development of PMS
oGenerally concluded that pharmacological doses of Vitamin B6 in range of 50-100mg /day reduce severity of
premenstrual depressive symptoms in some women
oSometimes used in clinical practice to diminish PMS symptoms
oUL for Vitamin B6 is 100mg/day
Obesity and Fertility
- Rates of reproductive health problems related to excess body fat are increasing in the US and other countries along with rising
rates of obesity
- Among 20-39 year olds in US, 23.3% of men and 27% of women are obese
-Prevalence of severe obesity, assessed as BMIs of 40kg/m2 or higher (weights that are 100 pounds higher than normal), has
increased around 5%
- Men who are obese are at risk of infertility due to low levels of testosterone and Sex Hormone Binding Globulin (SHBG)
oProtein that binds with the sex hormones testosterone and estrogen. Proteins become inactive when bound to SHBG but
are available for use when needed
- Obesity in women increase risk of infertility due to highly irregular or anovoluntary menstrual cycles
Biological bases of infertility in obese men and women
Men Women
- Low testosterone and SHBG levels
- Elevated leptin, follicle stimulating hormone (FSH), and
estrogen levels
- Decreased sperm count, sperm motility; increased malformed
- Oxidative stress, inflammation
- High estrogen, free-testosterone, and leptin
- Reduced levels of SHBG
- Insulin resistance
- Oxidative stress, inflammation
- Irregular menstrual cycles contribute to a lack of early prenatal care in some obese women
oSome women may not know they are pregnant because delayed onset of menstrual cycle may not be unusual
- Insulin Resistance – insulin can bind to specific receptors on the ovary and stimulate testosterone production. Androgens such as
testosterone suppress follicular grown, leading to ovulatory dysfunction
- Metabolic Syndrome – Cluster of abnormal metabolic and other health indicators. Characterized by insulin resistance, abdominal
obesity, high blood pressure and triglyceride levels, low levels of HDL cholesterol and impaired glucose tolerance
- Polycystic Ovary Syndrome (PCOS) – Characterized by insulin resistance, high blood insulin and testosterone levels, obesity,
polycystic ovaries, menstrual dysfunction, amenorrhea, infertility, hirsutism (excess body hair), and acne
Central Body Fat and Fertility
- Waist circumference of 35 inches or greater in women and over 40 inches in men is risk factor in impaired fertility
- In general, it takes women with high central body fat stores longer to become pregnant than it does women with low levels of
central fat
Weight Loss and Fertility
-Studies have shown that weight loss of 7-22 pounds in women with BMIs over 25kg/m2, and of 100 pounds in massively obese
men are related to a return of fertility in most participants
- Weight loss accomplished by women by diet and exercise and men by weight-loss surgery
- Diets
oShould be healthful, balanced, and provide all required nutrients in amounts recommended
The Female Athlete Triad and Fertility
- Consists of 3 major conditions: amenorrhea, disordered eating, and osteoporosis
- Amenorrhea – triggered when energy intake is about 30% less than energy requirement. This level of energy deficit leads to a
loss of normal secretion of luteinizing hormone (subsequent lack of estrogen production, and other hormonal changes
oMetabolic changes triggered by hormonal shifts result in decreased bone density and increased susceptibility to stress
fractures in affected athletes
Nutritional Management of the Female Athlete Triad
- Treatment focuses on correction of negative energy balance and associated eating disorders, and on restoration of bone mass
Eating Disorders and Fertility
- Anorexia and bulimia related to menstrual irregularities and infertility
- Amenorrhea in anorexia is related to irregular release of GnRH and very low levels of estrogen
oGenerally returns upon weight gain, but infertility can persist even after normal weight attained
May be related to continued low levels of body fat, low dietary fat intake, excessive exercise, or others
- Food binges and crash diets with Bulimia are related to low FSH and LH levels, menstrual disturbances, and infertility
Diabetes Mellitus Prior to Pregnancy
- High blood glucose levels during the first 2 months of pregnancy are teratogenic
oExposures that produce malformations in embryos or fetuses
oAssociated with two- to threefold increase in congenital abnormalities in newborns
- High blood glucose levels during the first 2 months in utero is related to malformations of the pelvis, central nervous system
(CNS), and heart in newborns, as well as higher rates of miscarriage
- Type I Diabetes – high blood glucose levels resulting from destruction of insulin-producing cells of the pancreas
- Type II Diabetes – high blood glucose levels due to the body’s inability to use insulin normally, or to produce enough insulin
oBecoming increasingly common in young adults and children due to the obesity epidemic
Nutritional Management of Type I Diabetes
- Blood glucose control, resolution of coexisting health problems, and health maintenance
oDiets controlled in carbohydrate content (carbohydrates raise blood glucose levels and increase insulin need to a greater
extent than do protein or fats)
- Urged to replace simple sugars with reasonable amounts of artificial sweeteners
- Foods low in glycemic index (GI) and high in fiber are encouraged, as are brightly coloured fruits and vegetables, low fat meat
and dairy products, fish, dried beans, and nits and seeds
- Physical activity improves blood glucose levels, physical fitness and insulin utilization
Nutritional Management of Type II Diabetes
- Some can manage glucose levels with diet and exercise, some need oral medication that increases insulin production or
sensitivity, or insulin to further boost glucose absorption into cells
- Dietary prescriptions mist be tailored for every person
- American Diabetes Association’s guidelines recommend:
oWeight loss of 7% of body weight or more
o% of total calories from energy nutrients: 1-20% proteins, <30% fat, and approx. 50% carbs
o% total calories from saturated fat = <7%, % total calories from trans fat = as low as possible
oRestriction of cholesterol intake to 200mg/day or less
o14g fiber per 1000 calories of food intake
oWhole grains = 50% of all grain intake
oLow GI foods that are rich in fiber and other important nutrients encouraged
- Glycemic Index
oMeasure of the extent to which 50g or carbohydrate-containing foods raise 2-hour postprandial blood glucose levels
compared to 50g of glucose or white bread
Other Components of the Nutritional Management of Type II Diabetes
- Individuals with diabetes are at risk for heart disease due to abnormal blood lipid levels
- Diets recommended include foods that improve blood lipid concentrations
- Diets that help lower high-LDL cholesterol without lowering concentrations of HDL cholesterol, and that lower elevated
triglyceride levels follow:
oFat mainly in form of monounsaturated fatty acids (vegetables, olive oil, peanuts and peanut oils, nuts, and seeds)
oIntake of saturated fats from animal products <7% of total calories
oLimit cholesterol intake to <200mg/day
oMinimize intake of trans fats from bakery products, fried foods, and snack foods
- Consuming 2-3 servings of fish per week (or taking fish oil supplements) lowers blood triglycerides in people with elevated
Reducing the Risk of Type II Diabetes
-Prediabetes – blood glucose levels are higher than normal but not high enough for the diagnosis of diabetes
oCan be postponed of prevented by interventions that reduce body weight
oStudy over 3 years: losses in body weight of approx. 7% and 150 mins of exercise reduced the risk of developing type II
diabetes by 50%