Nutrition 101 and Optometry: PART 1
Nutrition 101 and Optometry: PART 1
Having a basic knowledge of nutrition enables you to enhance patient care, which increases your practice's income.
JEFFREY ANSHEL O.D., Carlsbad, Calif. and
ILLUSTRATION BY NICK ROTONDO
ELLEN TROYER, MT, MA, Colorado Springs, Colo.
You should have a basic knowledge of nutrition for the following reasons:
► Several studies have established a link between nutrition and ocular health. For example, researchers have shown that Omega-6 fatty acids alleviate dry-eye symptoms.1,2
► You'll most likely find yourself in conversations with your patients regarding general nutrition, if you haven't already. This is because nutrition is a very popular topic. For instance, the U.S. Department of Agriculture's (USDA) food pyramid Web site (www.mypyramind.gov) has received almost 4.7 billion hits (as of May 2008) since it released the MyPyramid food guidance system in April 2005.
If you can answer your patient's questions about nutrition, you'll further solidify yourself as their primary-eyecare practitioner.
► It shows your patients and fellow healthcare practitioners that the field of optometry surpasses refraction.
► It enables you to make recommendations that may not only enhance a patient's vision but improve their overall health. Care that exceeds expectations binds patients to your practice. This, in turn, leads to referrals, which grows practice revenue.
► If you practice in a rural area, you may be the only practitioner older patients see on a regular basis. For this reason, many of them rely on you for their overall healthcare needs. You can, in part, meet these needs by asking probing questions about diet and medications, such as statins, which can produce side effects that you can counteract with nutritional supplementation.
► More than 60% of the U.S. population is now considered overweight and clinically obese, according to the most recent National Health And Nutrition Examination Survey (NHANES).3 You can play a role in eradicating these epidemics by discussing the roles diet, nutrition and portion control not only play in degenerative eye diseases, but in the body's overall health.
Currently, no specific guidelines exist for optometrists on how to initiate conversations with their patients regarding nutrition or how, specifically, to provide this information. We hope to develop these guidelines for you through the newly formed Optometric Nutrition Society (ONS) (www.optometricnutritionsociety.org).
This month (June), ONS will hold a director's meeting at which the directors will discuss the launch of an in-office nutrition program for optometrists.
Some preliminary ideas for the program: tips for you on how to ask patients about their nutrition, the formation of a nutrition-intake form, how to evaluate the form, the type of recommendations you should make based on the form and your discussion with the patient and how to do it all in a timely manner.
Because the first step to incorporating nutrition into your practice is to acquire basic knowledge of nutrition's role in the body, this two-part series will provide you with this education. (See "Nutrition Web Sites" below for additional information.)
Here, in part one, we discuss protein, the fats and carbohydrates.
|Nutrition Web Sites|
- U.S. Food and Drug Administration Information About Nutrition: www.cfsan.fda.gov/~dms/wh-nutr.html
- American Heart Association Diet & Nutrition: http://americanheart.org/presenter.jhtml?identifier=1200010
- American Dietetic Association Nutrition Fact Sheets: www.eatright.org/cps/rde/xchg/ada/hs.xsl/nutrition_350_ENU_HTML.htm
- Food and Nutrition Service. "Eat Smart. Play Hard" For Educators: www.fns.usda.gov/eatsmartplayhardeducators/
- United States Department of Agriculture (USDA) Economic Research Service: www.ers.usda.gov/Publications/EIB33/
- USDA Food and Nutrition Research Briefs: www.ars.usda.gov/is/np/fnrb/
- Nutrition.gov.: www.nutrition.gov/nal_display/index.php?info_center=11&tax_level=1
Protein is the most essential macromolecular nutrient for the human body.4 It provides the body with energy, and the body needs it for the manufacture of hormones, antibodies and enzymes, making it vital for growth and development. It also helps to maintain the body's proper acid-alkaline balance.
The body uses protein in the form of amino acids to build and maintain every cell. Molecular biologists estimate that several billion cells die in our bodies daily.5 Protein helps to replace these cells and carries out the myriad of metabolic reactions, such as nerve-cell creation, that happen every minute within our bodies. Proteins are made of two groups of amino acids: essential and non-essential.
The two types of proteins:
► Complete proteins. Complete Proteins are made of essential amino acids. The body can manufacture most amino acids (think non-essential) as long as it's ingesting the eight to 10 essential amino acids, which are leucine, isoleucine, valine, methionine, threonine, lysine, histidine, phenylalanine, trypophan and arginine. The only foods that contain 100% of each of the essential amino acids are animal source protein items, such as beef, chicken, fish, etc. and soybeans.
► Incomplete Proteins. These foods provide amino acids, but one or more of the essential amino acids is either missing or present in too small amounts to make the protein bio-available. These proteins are most often vegetable proteins, such as beans, peas, nuts, seeds and grain. This doesn't mean they are of no use, but they must combine with essential amino-acid proteins at the same time to provide the missing amino acids, so the body can use them.
For instance, although beans and rice are both quite rich in protein, each lacks one or more of the essential amino acids. When you combine beans and rice with each other, however, or when you combine either one with any of a number of other protein-rich foods, such as nuts, you form a complete protein that is a high-quality substitute for meat. In biochemistry, "The All Or None Law Of Protein Utilization" means that any given protein food is limited in the amount of protein that it can provide to the human body by the level of the lowest amino acid.
(For more information on the proteins, visit www.cdc.gov/ncccphp/dnpa/nutrition/nutrition_for_everyone/basics/protein.htm.)
Despite what the media has told us, fats aren't our enemy. In fact, they provide the most concentrated source of energy of all food groups.6 Fats transport all fat-soluble vitamins, such as A, D, E and K, and they keep calcium readily available to bones and teeth.
The three forms of fats:
► Saturated Fats. This fat is always present in animal products, such as beef, and tropical oils, such as coconut and palm. Saturated fats are generally solid at room temperature and are very stable due to their molecular structure.
For way too long, the media has told us that saturated fats cause bodily ailments, such as heart disease. This isn't exactly true. Clinical studies through past decades continue to prove that saturated fats, in moderation, are far healthier for the heart and vascular system than hydrogenated vegetable oils (trans-fats), which too easily become rancid and form damaging, dangerous free radicals.7
► Trans-fats. Indiscriminate use of hydrogenated (trans-fats) vegetable oils has greatly compromised our state of health. Trans-fat is produced when food manufacturers superheat the vegetable oil (often soy or corn) with a metallic agent and hydrogen — a process called hydrogenation. Complete hydrogenation produces a solid fat. Partial hydrogenation occurs when the food manufacturer halts the hydrogen process early — creating a soft product, such as soft-spread margarine. The result of any form of hydrogenation: Processed foods containing these fats have an increased shelf life, saving food manufacturers production costs, while increasing health risks.
Although the Food and Drug Administration (FDA) now requires that all food labels identify the amount of trans-fats, partially hydrogenated fats appear in the "Ingredient" section of the "Nutrition Facts" labeling. This is because the FDA's definition of trans-fats doesn't include partially hydrogenated fats.8 So, the cookies you or your patients eat may contain a banner across the box that reads "No Trans-fats," but if you see "partially hydrogenated" listed under "Ingredients," your cookies do indeed contain trans-fats.
|Gycemic Index, Fiber and Insulin — Glucagon Balance|
|The Glycemic Index (GI) describes how carbohydrate-containing food affects blood glucose levels. When we eat carbohydrates, our body breaks them down to produce glucose.|
For glucose to move from the blood into the body's cells, it needs a polypeptide hormone called insulin, which along with glucagon (stimulated through protein intake) plays a key role in determining whether our body burns fat or carbohydrates for energy. The pancreas produces both insulin and glucagon. Whenever glucose is present in the blood, insulin is stimulated. And, whenever protein is present, glucagon is stimulated. If the insulin is insufficient, however, glucose levels rise. A high level of insulin forces the body to burn carbohydrate rather than fat, which allows fat to accumulate in the body. Therefore, if we control the rate of glucose our body absorbs, we'll also control the amount of insulin secreted. This is where the Glycemic Index and fiber comes into play.
The Glycemic Index (GI) is a ranking of carbohydrates on a scale from 0 to 100 according to the extent to which they raise blood sugar levels after eating. (Visit www.glycemicindex.com for the index and database.)
Foods and drinks with a high GI, such as fruit juices, sugary sweets, etc., are those that the body rapidly digests and absorbs and result in an excess of insulin in the blood stream. Controlling the Glycemic Index of these foods and drinks allows for control over food-driven insulin stimulation (hyperinsulinemia) and reactive hypoglycaemia.
Low-GI foods, by virtue of their slow digestion and absorption, produce gradual rises in blood sugar and insulin levels, allowing the body to utilize the glucose formed from the breakdown of complex carbohydrates, instead of storing it in a fat cell as glycogen. As a result, low-GI foods have proven benefits for health. They typically also contain soluble fiber, which is often lacking in the diet.
For instance, research has shown that low-GI diets improve both glucose and lipid levels in people who have diabetes (type 1 and type 2).13 In addition, low-GI diets have benefits for weight control because they help control appetite. Also, low GI diets reduce insulin levels and insulin resistance. Furthermore, considerable evidence exists supporting the value of a low-GI (below 55) diet for individuals who have hyperlipidemia (high triglycerides or cholesterol) and for prolonging endurance during physical activity — improving insulin sensitivity, reducing food intake and increasing colonic fermentation.
► Unsaturated fats. Vegetables, such as corn, and grains, such as rice, barley and bran, contain these fats. The unsaturated fats have an open molecular structure, which makes them (generally) liquid at room temperature and highly susceptible to damage from oxidation. This damage dramatically accelerates upon heat to high temperatures, such as during frying. These fat oils are, in part, responsible for artery damage, leading to atherosclerosis, which can lead to heart disease.
If you graph the consumption of vegetable oils and the incidence of heart disease, you'd most likely notice that they both increase at almost the same rate.
► Monounsaturated fats. You can find these fats mostly in vegetable and nut oils, such as olive, peanut, avocado and canola. They appear to reduce the low-density lipoprotein (LDL) blood level without lowering the high-density lipoprotein (HDL) level in any way.9 This positive impact upon LDL cholesterol, however, is relatively modest.
The fats in the foods you consume daily shouldn't total more than 25% to 35% of the calories you eat in a given day. In addition, for good health, the majority of those fats should be mono- or polyunsaturated.10
(For more information on dietary fats, visit www.cdc.gov/nccdphp/dnpa/nutrition/nutrition_for_everyone/basics/fat.htm.)
Carbohydrates are one of the main dietary components.11 The primary function of carbohydrates is to provide energy for the body, particularly the brain and the nervous system. The Standard American Diet (SAD) reveals that we consume highly concentrated, overly refined carbohydrates, such as high-fructose corn syrup, that deliver more units of sugar than our bodies can possibly utilize in a short time. (Visit www.plim.org/SAD.htm.) In fact, there's a relationship between the introduction of relatively inexpensive high-fructose syrup and the U.S. diabetic epidemic.12
The body stores this sugar as glucose (our cells' main energy source) for energy. The body converts the excess glucose to glycogen (a polysaccharide), which the body then converts to triglycerides (naturally occurring esters of three fatty acids and glycerol that is the chief constituent of fats and oils). The body stores triglycerides for future use. The "future use" rarely happens, however, because most of us have an excess supply of sugar-forming foods in our daily diet and don't get enough exercise. The end result is the U.S. obesity epidemic and all the related health challenges facing today's society, such as diet-related eye disease (i.e. diabetic retinopathy and an increased risk for agerelated macular degeneration).
The two types of carbohydrates:
► Complex carbohydrates. Foods with complex carbohydrates include whole grains, such as bran, and vegetables, such as potatoes, which are best consumed in their natural state. These foods are low on the Glycemic Index (See "Glycemic Index, Fiber and Insulin — Glucagon Balance," above).
► Simple or Refined Carbohydrates. The simple carbohydrates include most fruits, such as fructose and galactose, and some vegetables that contain maltose. The body digests them easily, and they don't provide an excessive amount of glucose. Glucose in excess causes glycation, which can lead to a break down in blood vessels.
The body cannot easily digest refined carbohydrates, such as white flour, and sugar foods, such as candy. As a result, refined carbohydrates push highly concentrated amounts of glucose into the bloodstream, which the body quickly stores. Long-term storage occurs through triglycerides in adipose cells, which become large, making burning them off difficult. All simple or refined carbohydrate foods are high on the Glycemic Index.
(For more information on carbohydrates, visit www.cdc.gov/nccdphp/dnpa/nutrition/nutrition_for_everyone/basics/carbohydrates.htm.)
Now that you know the role the three macronutrients (proteins, fats and carbohydrates) play in the body, in part two, we'll discuss the basics of micronutrients that the body must ingest to complete the metabolic process of gaining energy. This will include the vitamins, minerals, bioflavonoids, carotenoids, and essential fatty acids. OM
- Kokke KH, Morris JA, Lawrenson JG. Oral omega-6 essential fatty acid treatment in contact lens associated dry eye. Cont Lens Anterior Eye. 2008 Feb 27
- Creuzot C, Passemard M, Viau S, et al. Improvement of dry eye symptoms with polyunsaturated fatty acids. J Fr Ophtalmol. 2006 Oct;29(8): 868-73.
- Center for Disease Control. National Center for Health Statistics. Prevalence of Overweight and Obesity Among Adults: 1999-2002. www.cdc.gov/nchs/products/pubs/pubd/hestats/obese/obs e99.htm Accessed May 22, 2008.
- MedlinePlus. Medical Encyclopedia. Protein in diet. www.nlm.nih.gov/medlineplus/ency/article/002467.htm Accessed May 22, 2008.
- Brenner S, Horvitz R and Sulston JE. The Nobel Prize Summary in Physiology or Medicine 2002. http://nobelprize.org/nobel_prizes/medicine/1/laureates/2002/press.html. Accessed May 22, 2008.
- Australian Government. Ministry of Health. Nutrient Reference Values for Australia and New Zealand. Fats. Total Fats and Fatty Acids. www.nrv.gov.au/Nutrients.aspx?code=226358006. Accessed May 22, 2008.
- Chandrasekharan N. Changing concepts in lipid nutrition in health and disease. Med. J Malaysia. 1999 Sep;54(3): 408-27.
- Guidance for Industry: A Food Labeling Guide. Trans Fat Labeling. www.cfsan.fda.gov/~dms/2lg-7b.html #transfat. Accessed May 15, 2008.
- Kris-Etherton PM. Circulation. AHA Science Advisory. Monosaturated Fatty Acids and Risk of Cardiovascular Disease. http://circ.ahajournals.org/cgi/content/full/100/11/1253. Accessed May 22, 2008.
- American Heart Association. Monounsaturated Fats. www.american heart.org/presenter.jhtml?identifier=3045 795#limit_mono. Accessed May 22, 2008.
- Medline Plus. Medical Encyclopedia. Carbohydrates.www.nlm.nih.gov/medlineplus/ency/article/002469.htm Accessed May 22, 2008.
- Ouyang X, Cirillo P, Sautin Y, et al. Fructose consumption as a risk factor for non-alcoholic fatty liver disease. J Hepatol. 2008 Jun;48(6):993-9.
- McMillan-Price J, Petocz P, Atkinson F, et al. Comparison of 4 diets of varying glycemic load on weight loss and cardiovascular risk reduction in overweight and obese young adults: a randomized controlled trial Arch Intern Med. 2006 Jul 24;166(14): 1466-75.
|Dr. Anshel has written numerous articles and books regarding nutritional influences on vision and computer vision concerns. He is the founder of Corporate Vision Consulting and is President of the Optometric Nutrition Society. E-mail him at firstname.lastname@example.org.|
Ms. Troyer has more than 30 years experience in medical science and professional education services. She is the co-inventor of oral formulations designed to address dry-eye disease. Ms. Troyer is on the Science Committee of the Optometric Nutrition Society. E-mail her at email@example.com
Optometric Management, Issue: June 2008