The skinny on healthy skin


Your skin is your largest organ.  On average, this amounts to about 2 square meters of surface and roughly 3 to 4 kilograms of mass. It helps protect you against potentially harmful substances, extreme temperatures and the Sun’s ultraviolet light. In turn, the skin’s three layers – the epidermis, dermis, and subcutis – depend on you to keep them healthy.  This means taking precautions to avoid the Sun’s damage and meeting your nutritional requirements on a regular basis.

Eat right

Aside from scheduling regular visits to the dermatologist, avoiding direct Sun light for extended periods of time, and wearing Sun screens (hats, long sleeves, umbrellas, lotions), you can make sure you consume a healthy diet which includes vitamins A, B, C, E and omega-3 fatty acids.

Vitamin A

Vitamin A refers to three compounds (retinol, aldehyde, and retinoic acid) called retinoids.  Plants contain carotenoids which are metabolized by the body to form retinoids, the most important of which is B-carotene.  About 50% to 80% of vitamin A in the body is stored in the liver.  The rest is spread out among the lungs, kidneys, adipose tissue and a number of specialized cells throughout the body (1).

Known by most people as being crucial for good vision, vitamin A also plays a role in cell function, growth, development and differentiation (and, thus, is important in keeping our skin healthy), immune function, reproduction and a number of systemic functions, such as gene expression.

The RDA for adults is 700-900 RAE (retinol activity equivalents) which translates into 700-900 mcg of retinol or 8,400-10,800 mcg of B-carotene per day, depending on gender and pregnancy status (1).

  • 1 small sweet potato = 7,374 RAE (about ten times the RDA, or 88,488 mcg of B-carotene)
  • 1 cup raw carrots = 5,553 RAE
  • 1 cup of cooked broccoli = 725 RAE
  • 2 medium tomatoes = 860 RAE
  • 1 cup cooked spinach = 6,882 RAE
  • 1 cup cantaloupe = 1,625 RAE

Given the abundance of carotenoids in the plant world, particularly in the orange and red fruits and vegetables category, it is relatively easy to meet our daily requirements.

Supplementation with vitamin A is contraindicated in the absence of a known deficiency and without medical supervision.  Although readily available in our food supply, vitamin A may be poorly absorbed by some individuals who suffer from pancreatic or liver disease or who lack fat and/or zinc in their diets. On the flip side, vitamin A toxicity is serious business. Regular consumption of vitamin A at 100 times or more the RDA may lead to liver disease, skin disorders, higher incidence of bone fractures (including hip) and lung cancer among smokers (1).

B vitamins

B vitamins, in particular niacin, help keep skin healthy.  Niacin is essential for energy production and metabolism.

Niacin in most plants and grains is covalently bound with peptides and carbohydrates that are not released during digestion. However, alkaline hydrolysis (the addition of water and alkali) makes niacin bioavailable (the Central American tradition of soaking grains in lime water before cooking is, thus, more than just a dietary preference as it serves an important purpose). Niacin is also synthesized from tryptophan (an essential amino acid) with moderate efficiency (60 mg of tryptophan yield 1 mg of niacin) (1).

Ready to eat cereals have the highest niacin content (up to 26 mg per serving, depending on brand).  Mushrooms, peanuts, coffee, breads and pasta all yield enough niacin to meet daily recommendations from just one serving.  Current DRI for adults is anywhere from 2 – 18 mg depending on age and gender (1).

Vitamin C

Vitamin C, aka ascorbic acid, is involved in many electron transport reactions, some of which are involved in collagen synthesis.  Collagen is a fibrous protein found primarily in connective tissue, cartilage, bone, teeth, skin and tendons.  Needless to say, it is important for maintaining healthy skin.  Lucky for us, vitamin C is abundant in most fruits and vegetables, making it relatively easy to meet daily requirements (15 to 120 mg per day depending on age and gender)(1).  In spite of this, vitamin C is one of the most commonly overconsumed supplements in the US and Canada. I can only guess that its popularity rests with the misguided belief that it prevents or cures the common cold.

Too much of this good thing may result in GI disturbances, an increased risk of some cancers (whereas, normal intake has the opposite effect), slight oxaluria, and false-positive urinary glucose test results (1).

Vitamin E

Vitamin E is the most important fat soluble antioxidant in the cell as it protects cell membranes from free radical activity.  It depends on other nutrients and enzymes to do its job, particularly copper, zinc, riboflavin and manganese.

Vitamin E is measured in terms of a-tocopherol equivalents (a-TE) of which adults need about 15 mg per day.

Tocopherols (and tocotrienols) are only synthesized in plants.  The average American, and to a lesser extent, the average Canadian, consumes most of his/her vitamin E in the form of vegetable oil even though healthier sources abound.  One ounce of almonds yields a whopping 7.33 mg (more than three times the amount found in one tablespoon of canola oil)(1).

Omega-3 fatty acids

There are three types of omega-3 fatty acids:  a-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexanoic acid (DHA).  Of these, ALA is an essential fatty acid (EFA), meaning it can not be synthesized by the human body, so, we must get it from food. Humans can desaturate and elongate ALA into EPA and DHA as needed, thus, it is important to include ALA in the diet on a regular basis (1).

The conversion rate of ALA to EPA and DHA is relatively low in persons who consume fish.  However, in vegetarians and vegans, the conversion rate is significantly higher, which explains the similarity of EPA and DHA levels between these groups and their meat-eating cohorts (2).  It is not necessary for vegetarians or vegans to supplement with EPA and DHA as long as they consume a healthy diet that meets their nutritional needs.  In all groups, conversion rates of ALA to EPA and DHA are higher in women (3).

EFA deficiency is rare and occurs primarily among newborns and infants.  Even in developing countries, where food is scarce, EFA deficiency is very low most likely because the most commonly consumed type of fat in such areas is usually vegetable based (vegetable fat is a good source of ALA)(4).

Water

Lastly, stay hydrated inside and out.  Rather than smother your skin with lotion (which can actually draw moisture out of the skin), use a water bottle set on “mist” instead.  Obviously, this may not be the thing to do at the office, but while you’re outdoors or at home, opt for water.  It doesn’t cost anything and it is better for your skin than most other topical applications.

REFERENCES

  1. Mahan LK, Escott-Stump S. Krause’s Food and Nutrition Therapy. MO: Saunders-Elsevier; 2008.
  2. Welch AA, Shakya-Shrestha S, Lentjes MAH, Wareham NJ, Khaw KT. Dietary intake and status of n-3 polyunsaturated fatty acids in a population of fish-eating and non-fish-eating meat-eaters, vegetarians, and vegans and the precursor-product ratio of a-linolenic acid to long-chain n-3 polyunsaturated fatty acids: results from the EPIC-Norfolk cohort. Am J Clin Nutr, 2010;92:1040-51.
  3. Burdge GC. Metabolism of a-linolenic acid in humans. Prostaglandins, leukotrienes and essential fatty acids, 2006;75(3):161-8.
  4. The Merck Manual for Health Care Professionals. Available at: http://www.merckmanuals.com/professional/nutritional_disorders/undernutrition/essential_fatty_acid_deficiency.html  Accessed: August 9, 2012.
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Protein powders and shakes


A few decades ago, protein powders used to lurk in gyms and so-called “health” food stores. They were stacked neatly on shelves amidst colourful ads that lured would-be buyers with images of famous bodybuilders and athletes whose physiques few of them would ever match. In those days, their primary targets were body builders. Claims varied, but most brands promised increased muscle gain that, according to the ads, run of the mill, food derived protein could not possibly provide.

Today, protein powders have escaped the confines of gyms and health food stores and have become ubiquitous on food market shelves, in pharmacies, and virtually anyplace else food, supplements, or pharmaceuticals are sold. Their user base has changed dramatically to include athletes (professional sports people who are not bodybuilders), recreational athletes (sport hobbyists and/or fitness enthusiasts), and lifestyle users (consumers who think protein powders are healthy snacks and/or will help them lose weight)(1). Vegetarian and vegan consumers of protein powders tend to fall in the last two categories and are likely to believe the powders, or other similar supplements, are necessary to meet their daily protein needs. Some users claim they “feel better” and have more energy when they consume protein powders, while others simply believe that without their daily dosage, their muscles would vanish into thin air.

ENERGY

“The extra protein gives me energy!” is a claim I hear surprisingly often. It is surprising because protein is a lousy source of energy. It is a last resort the body will tap when it runs out of its preferred fuel (particularly during exercise): glycogen (aka stored carbohydrate)(2). You may have heard of athletes engaging in something called “carb-loading” before events. This consists of consuming a higher ratio of carbohydrates to help the body handle the energy requirements of extended activity, particularly if the event involves increasing pace and effort to beat the competition (3). The more intense the exercise, the more carbohydrate the body burns. Consuming carbs before and during exercise helps athletes keep up the pace. In fact, a high carbohydrate diet increases endurance time three-fold when compared to a high protein diet (3). Once glycogen runs out, so does your energy and ability to keep going. Similarly, failing to replenish your glycogen stores after exercise, will impair your ability to recover and achieve your training goals.

During periods of extended low intensity exercise, such as walking, fat becomes an important source of energy, more so if you engage in regular exercise. The more you train, the more your body uses fat for energy when you are resting or performing less strenuous activities. As you pick up the pace, your body switches back to using glycogen.

Image source:  McArdle et al. – Sports and Exercise Nutrition, 3rd Ed., Chapter 5, Macronutrient Metabolism in Exercise and Training, page 157 (3).

In a nutshell, if you’re looking for extra energy, put away the protein powder and have some healthy carbs instead.

MORE MUSCLE

Muscle growth occurs as the result of training, not from the overconsumption of protein. There is only so much protein the body will use before it stores the excess away. Protein powders are digested faster than food derived protein, making protein available for muscle repair in a more expedited manner. “Aha!” you might say, “so, they ARE good for something!” Well, not really. In the long run, the end result is about the same – except, perhaps, for your wallet.

Studies looking at the effects of supplementation and strength training combined show insignificant or no difference between placebo and control groups (2,4).  In their 2009 joint position paper on nutrition and athletic performance, the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine concluded the following (5):

“Current evidence indicates that protein and amino acid supplements are no more or no less effective than food when energy is adequate for gaining lean body mass. Although widely used, protein powders and amino acid supplements are a potential source for illegal substances such as nandrolone, which may not be listed on the ingredient label.”

In other words, as long as you meet your body’s protein requirements, it doesn’t make much difference if you’re getting the protein fast, from a powder, or slower, from food. What matters most is timing (6). Consumption of protein and carbohydrate containing foods immediately after training is far more important if you want to see results. The sooner you eat, the better. Letting as little as two hours pass after a workout without eating will lead to a lot of disappointment on your part if you’re looking to build muscle mass (7).

PRE-, DURING and POST-EXERCISE NUTRITION

For best results in terms of performance and overall health (the latter is sometimes overlooked when people consider a plan of action in the short term), remember that supplements are not a replacement for healthy food choices.

Eat breakfast, consume the appropriate amount of calories for your body (don’t forget to eat healthy fats), stay hydrated and be sure to eat before and after exercise. If you like coffee or tea, you may be surprised to know that caffeine is an effective ergogenic aid, particularly in racing events, but also in short term, high intensity events, if consumed one hour before exercise (8,9). If you’ve given up coffee and tea because you think it will hinder your performance, dehydrate you, or interfere with electrolyte balance, you may want to reconsider your choice (8,9,10).

While studies on the effects of protein restriction on performance have yielded inconclusive results, the same is not true when it comes to carbohydrate restriction which has been shown to be detrimental (11,12). The importance of carbohydrate consumption after workouts can not be overemphasized. The aforementioned position paper on nutrition and athletic performance provides the following guidelines for performance athletes (5):

  • Carbohydrate recommendations for athletes range from 6-10 g/kg (2.7-4.5 g/lb) body weight per day depending on extent and duration of exertion (5).
  • Protein recommendations for endurance and strength trained athletes range from 1.2-1.7 g/kg (0.5-0.8 g/lb) body weight per day. The authors stress that food sources can easily meet requirements and supplementation is not necessary (5).
  • Fat intake should range from 20%-35% of total energy intake. Note that consuming less than this will not improve performance (5).
  • Before exercise, a meal or snack “should provide sufficient fluid to maintain hydration, be relatively low in fat and fiber to facilitate gastric emptying and minimize gastrointestinal distress, be relatively high in carbohydrate to maximize maintenance of blood glucose, be moderate in protein, be composed of familiar foods, and be well tolerated by the athlete.”(5)
  • During exercise, it is important to replace fluid losses and “provide carbohydrates (approximately 30-60 g per hour) for maintenance of blood glucose levels.”(5)
  • After exercise, “a carbohydrate intake of ~1.0-1.5 g/kg (0.5-0.7 g/lb) body weight during the first 30 minutes and again every 2 hours for 4 to 6 hours will be adequate to replace glycogen stores. Protein consumed after exercise will provide amino acids for building and repair of muscle tissue.”(5)

To put things in perspective, let’s consider the nutritional requirements of a 160 pound male professional soccer player:

Calories: approx. 4,000 per day
Protein: approx. 110 grams per day, or 11% of daily calories
Carbs: approx. 640 grams per day, or 64% of daily calories
Healthy Fats: approx. 111 grams per day, or 25% of daily calories

Notice that although 110 grams of protein per day represents quite a bit more than the amount of protein recommended for weekend athletes or sedentary persons, this amount does not represent a higher percentage of daily calories. In other words, it is not added (or supplemented) protein.

BOTTOM LINE

If the only way you are meeting your protein requirements is by supplementing with protein powders, there is something wrong with your diet. It should not be difficult to meet the recommended 10% to 15% of your daily calories in the form of protein. In fact, I would be very surprised if this is the case, given the abundance of food varieties available in North America. In the unlikely event you are not getting enough protein or the necessary ratios of essential amino acids, tweaking your diet will be better for your health (and for your wallet) in the long run than starting a protein supplementation habit.

REFERENCES

  1. Overview of the Sports Nutrition Market—Food, Beverages and Supplements, 2010; ISSN 1920-6593 Market Analysis Report, AAFC No. 10745E.
  2. Maughan RJ. Nutrition in Sport – Volume VII of the Encyclopedia of Sports Medicine. MA: Blackwell Science, Inc.; 2000.
  3. McArdle WD, Katch FI, Katch VL. Sports and Exercise Nutrition, 3rd Ed. MD: Lippincott Williams & Wilkins; 2009.
  4. Williams AG, van den Oord M, Sharma A, Jones DA. Is glucose/amino acid supplementation after exercise an aid to strength training? Br J Sports Med, 2001;35:109-113.
  5. Nutrition and athletic performance. Journal of the American Dietetic Association, 2009; 109(3):509-527.
  6. Poole C, Wilborn C, Taylor L, Kerksick C. The role of post-exercise nutrient administration on muscle protein synthesis and glycogen synthesis. Journal of Sports Science and Medicine, 2010;9:354-363.
  7. van Essen M, Gibala MJ. Failure of protein to improve time trial performance when added to a sports drink. Med Sci Sports Exerc. 2006;38:1476-1483.
  8. Cox GR, Desbrow B, Montgomery PG, Anderson ME, Bruce CR, Macrides TA, Martin DT, Moquin A, Roberts A, Hawley JA, Burke LM. Effect of different protocols of caffeine intake on metabolism and endurance performance. Journal of Applied Physiology, 2002:93:990-999.
  9. Paluska SA. Caffeine and exercise. Current Sports Medicine Reports, 2003;2:213-219.
  10. Bell DG, McLellan TM. Effect of repeated caffeine ingestion on repeated exhaustive exercise endurance.  Medicine & Science in Sports & Exercise, 2003; DOI: 10.1249/01.MSS.0000079071.92647.F2
  11. Knechtle B, Knechtle P, Mrazek C, Senn O, Rosemann T, Imoberdorf R, Ballmer P. No effect of short-term amino acid supplementation on variables related to skeletal muscle damage in 100 km ultra-runners – a randomized controlled trial. Journal of the International Society of Sports Nutrition, 2011;8:6.
  12. Ivy JL, Res PT, Sprague RC, Widzer MO. Effect of a carbohydrate-protein supple- ment on endurance performance during ex- ercise of varying intensity. Int J Sport Nutr Exerc Metab. 2003;13:382-395.

The protein myth


There are a number of food myths currently in circulation, some of which have been around for decades.  They generally revolve around particular micro- and macro-nutrients, their sources, and/or their imaginary abilities to cure us of all sorts of ailments ranging from the common cold to cancer.  Among these, we find the “protein myth” which, in a nutshell, states that protein from animal foods is superior because it contains all essential amino acids.

WHAT ARE PROTEINS?

Proteins are the most complex of the three macro-nutrients. They are composed of long chains of amino acids and, in some cases, include other components that are strung together in complicated formations consisting of carbon, hydrogen, oxygen, and nitrogen.  Every cell in the human body contains protein. It is a major part of the skin, muscles, organs, glands and all body fluids, except bile and urine.  Proteins in the body act as enzymes (catalysts), messengers (hormones), structural elements, immunoprotectors (immunoglobulins or antibodies), transporters, buffers, fluid balancers, or receptors on cell surfaces.  They also play a role in cell adhesion, storage of minerals in the body, and as conjugated proteins (glycoproteins) (1).

Three types of amino acids fold into acid chains to form proteins.  They are:

Essential or indispensable amino acids

  • Essential amino acids cannot be made by the body. As a result, they must come from the foods we eat.
  • They are: histidine (infants only), isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.

Nonessential amino acids

  • “Nonessential” means that our bodies produce an amino acid, even if we don’t get it from the foods we eat.
  • They include: alanine, asparagine, aspartic acid, and glutamic acid.

Conditional amino acids

  • Conditional amino acids are usually not essential, except in times of illness and stress, and are made in the body.
  • They include: arginine, cysteine, glutamine, tyrosine, glycine, ornithine, proline, and serine.

The chains are held together by hydrogen bonds, and, sometimes, by ionic bonds, depending on how the chain is folded (i.e. positive and negative ions face each other), by van deer Waals dispersion forces, or by sulphur bridges.

HOW MUCH PROTEIN DO WE NEED?

Although the human body contains a large amount of protein, it does not need to consume large amounts to maintain itself.  According to the World Health Organization (WHO), the average adult needs to consume approximately 60 grams of protein per day (0.8 grams per kilogram of body weight or 10 to 15% of total calories (assuming daily caloric needs are met) (2). As far as amino acids are concerned, we do not need to consume all of the essential amino acids at every meal, but getting a balance of them over the course of a 24 to 48 hour period is important.

PLANT vs ANIMAL PROTEIN

Plants produce/contain all of the essential amino acids because they can not get them from their environment by consuming other living organisms (the exception being carnivorous plants such as the Venus Fly plant which “eats” insects).  The amino acid profile of each plant varies – for instance, beans are high in lysine, while grains are low in it, but both contain it.  There is no such thing as a plant that lacks one or more amino acids (3). It is surprising, and disappointing, to see that, in spite of all we have learned about nutrition in the past couple of decades, the notion that plants lack certain amino acids persists (often in places one would least expect to find such false assumptions).

It is not necessary to consume animal products to meet essential amino acid needs, as long as the diet includes plant foods from all the food groups and caloric needs are met. Keep in mind, there is enough protein in plants to grow elephants and Panda bears. Contrary to popular belief, animals don’t make the essential amino acids we require. They ingest them by consuming plants (or one another).

The terms “complete” and “incomplete” proteins, when referring to protein foods, are no longer considered accurate or useful, and educators are encouraged to abstain from using them in the classroom (4).  Such terms are misleading and can create confusion since “incomplete” proteins are often described as “lacking” one or more essential amino acids.  This, of course, is not true and can be easily verified by looking up the amino acid content of plant foods using the USDA National Agricultural Library Nutrient Database.

From Young and Pellet’s review on plant proteins in relation to human protein and amino acid nutrition – click on image for larger version (5).

Should you, for whatever reason, want to include so-called “complete” proteins in one single meal, you may consume any of the following:

  • Soy, or
  • Eggs, or
  • Dairy, or
  • Legumes + Grains (e.g. peanut butter sandwich, burrito), or
  • Legumes + Nuts  (e.g. lentils and cashews), or
  • Legumes + Seeds (e.g. hummus)

In a review of plant based diets and their adequacy in meeting amino acid needs, Millward concludes:  “it is clear that meat-free, largely plant-based diets available in developed countries can supply protein in the amount and quality adequate for all ages” (6).  Similarly, the American Dietetic Association (ADA), in its position paper on vegetarian diets, states the following:  “Plant protein can meet protein requirements when a variety of plant foods is consumed and energy needs are met. Research indicates that an assortment of plant foods eaten over the course of a day can provide all essential amino acids and ensure adequate nitrogen retention and use in healthy adults; thus, complementary proteins do not need to be consumed at the same meal(7).

In the same paper, the ADA further adds:  “Vegetarian diets are often associated with a number of health advantages, including lower blood cholesterol levels, lower risk of heart disease, lower blood pressure levels, and lower risk of hypertension and type 2 diabetes. Vegetarians tend to have a lower body mass index (BMI) and lower overall cancer rates. Vegetarian diets tend to be lower in saturated fat and cholesterol, and have higher levels of dietary fiber, magnesium and potassium, vitamins C and E, folate, carotenoids, flavonoids, and other phytochemicals. These nutritional differences may explain some of the health advantages of those following a varied, balanced vegetarian diet” (7).

Animal protein, on the other hand, has been associated with cardiovascular disease and cancer, even after confounders such as saturated fat have been taken into account (8,9).

A VEGETARIAN MENU

To illustrate the ease with which amino acid requirements are met on a meat-free diet, let’s look at a modest sample menu for a 170 lbs man in his 30’s.  The selection is modest on purpose, and not representative of the wide variety of plant based foods consumed by the average vegetarian or vegan.

Breakfast:

2 scrambled eggs (or, for vegans an equivalent amount of tofu scramble)
2 pieces of toast with margarine
1 glass of orange juice

Snack:

1 avocado

Lunch:

1 Frozen bean burrito, microwaved
1 Small salad (1 cup of shredded lettuce, 1 sliced tomato, with dressing)
6 oz. soy milk

Snack:

1/2 cup pistachio nuts

Dinner:

1 bowl vegetarian stew (peas, tomatoes, green beans, carrots, onions, parsnip, olive oil, seasonings)
1 cup mashed potatoes
1 tomato
2 slices of bread
1 small slice of cherry pie

Amino acid requirements for our subject:          Amino acid content of selected  menu:In this example, the vegetarian menu meets and surpasses the amino acid requirements of our hypothetical man.

Evidence that plant based diets can meet all of our essential amino acid needs abounds (1,3,4,5,6,7,9,10).  Yet, the myth persists.  Education, particularly in the medical community, is key to putting this silliness to rest.

REFERENCES

  1. Gropper SS, Smith JL, Groff JL. Advanced Human Nutrition, 5th Ed. 2009;179-182.
  2. World Health Organization. Nutrition Health Topics – Population nutrient intake goals for preventing diet-related chronic diseases. Available at: http://www.who.int/nutrition/topics/5_population_nutrient/en/index.html  Accessed February 21, 2012.
  3. Mangels R, Messina V, Messina M. The Dietitians’s Guide to Vegetarian Diets, 3rd Ed. 2011;65-83.
  4. Millward DJ.  The nutritional value of plant-based diets in relation to human amino acid and protein requirements. Proc Nutr Soc, 1999;58:249-260.
  5. Young VR, Pellett PL.  Plant proteins in relation to human protein and amino acid nutrition.  Am J Clin Nutr, 1994;59:1203S-12S.
  6. U.S. National Library of Medicine National Institutes of Health – Medline Plus Fact Sheets.  Protein in the diet. Available at:  http://www.nlm.nih.gov/medlineplus/ency/article/002467.htm  Accessed February 21, 2012.
  7. Position of the American Dietetics Association:  Vegetarian Diets. Journal of the ADA, 2009;109(7):1266-82.
  8. Preis SR, Stampfer MJ, Spiegelman D, Willett WC, Rimm EB.  Dietary protein and risk of ischemic heart disease in middle-aged men. Am J Clin Nutr, 2010;92:1265-72.
  9. Fontana L, Klein S, Holloszy JO. Long-term low-protein, low-calorie diet and endurance exercise modulate metabolic factors associated with cancer risk. Am J Clin Nutr, 2006;84:1456-62.
  10. Millward DJ, Fereday A, Gibson NR, Pacy PJ.  Human adult amino acid requirements: leucine balance evaluation of the efficiency of utilization and apparent requirements for wheat protein and lysine compared with those of milk protein in healthy adults. Am J Clin Nutr, 2000;72:112-21.