Food & Fitness After 50: Is There an Optimal Protein Intake for Older Adults?

A recent paper from three international protein gurus reviews the science behind the recommendations that older adults need more protein than young, healthy adults. The opening sentence of the paper sums up the current state of the science: “The optimum protein intake for adult health remains controversial.” How could that be?  The authors explain that why we know general requirements for protein we don’t know optimal intakes. Why there are limits to what we know about protein and aging?

  • Older adults, especially older women, are often not included as participants in research studies on protein needs.
  • Recommendations for protein are often derived from young, healthy adults. Healthy is a key word because we know that many older adults have chronic health conditions. Obesity, diabetes, high blood pressure, heart disease, and cancer affect 3 of 4 adults over the age of 65.
  • Research studies that look at protein intake and muscle mass in older adults are of short duration; most last less than 6 months. Since muscle loss is gradual, the short-term studies may not have time to show a positive effect of increasing protein.

While we may not have the definitive answer to the question posed in the title of this post, there is much we do know and here are some key points from the article:

  • The Recommended Dietary Allowance (RDA) for protein is inadequate for older adults due to something called the “anabolic resistance” of muscle. (Anabolic means building up and is the opposite of catabolic or breaking down.) Anabolic resistance means that the signals to build up muscle through strength training or eating protein is muted in older adults. This resistance can be overcome with an increased amount of strength training or a higher intake of protein.
  • When older adults experience a period of muscle disuse, which can occur during illness or injury, signals to muscle protein are blunted and a practical way to overcome this is through a higher protein intake, especially protein-rich foods that contain a key amino acid, leucine. Protein is made up of units called amino acids and 9 of the 22 amino acids are considered essential, meaning that we can’t make them in the body, so they must be consumed through diet. Leucine is one of the 9 essential amino acids and has been found to play a critical role in protein synthesis.
  • Sarcopenia, literally meaning vanishing flesh, is the progressive loss of muscle as we age. It doesn’t start when we are 60; it starts at about the age of 40 (even earlier in those who are inactive). Between the ages of 20 and 90, we can lose over 50% of our muscle mass due to sarcopenia and inactivity.

So, where does all of this leave us? The authors conclude that older adults should increase protein…both quality and quantity at meals. Consuming at least 30 grams of protein per meal, with 2.5 grams of leucine or more can overcome the anabolic resistance of aging muscle. While not all studies agree on meal timing, the authors also conclude that spreading the protein evenly across meals is better than backloading all the protein at one meal.

So, what does that mean for us? To recap to maintain muscle you need two things: progressive, resistance strength training and nutrition. Protein is a key nutrient for building and keeping muscle.  A few facts about protein:

  • High quality protein contains all 9 of the essential amino acids (EAAs) and includes:
    • Animal protein (beef, pork, poultry, fish, eggs, milk, cheese, cottage cheese, kefir, yogurt)
    • Soy protein (tofu, edamame, soy burgers, patties, crumbles, soymilk, cheese, yogurt)
  • The following foods do not contain all the EAAs, but they contribute to total protein intake:
    • Nuts (almonds, walnuts, etc.), almond butter, seeds (sunflower, chia, flax), legumes (peanuts, pinto, navy black beans, split peas, black-eyed peas, and other starchy beans and peas), peanut butter, pasta, rice, and whole grain bread.
  • Try and spread the protein evenly in 3-4 meals each day.

Examples of 30-gram protein meals

Sample meals and snacks with ~30 grams of protein

6 oz Greek yogurt (18)*

1 oz granola (4)

Small banana (1)

Skim milk latte (6)

2 scrambled eggs with 1 oz cheese and spinach (21)

8 oz soymilk (7)

½ slice whole grain toast (2)

Smoothie made with 1 ounce whey protein powder (20)**

6 oz Greek vanilla yogurt (18)

½ cup frozen berries (1)

Large green salad with veggies (2)

4 oz grilled chicken or salmon (28)

1 Tablespoon sunflower seeds (1)

1 Tablespoon chopped nuts (1)

3 oz tuna mixed with mayo (21)

2 slices of whole grain bread (7)

Lettuce, tomato, banana peppers or other veggies (2)

1 cup pasta (6)

3 oz turkey or beef meatballs (21)

Green salad with balsamic vinegar dressing (1)

1 cup cottage cheese (28)

1 Tablespoon chopped nuts (1)

3 slices fresh or canned peaches (1)

Stir fry with ½ cup tofu (10)

Carrots, broccoli, edamame (16)

1 cup brown rice (5)

3 oz cheddar cheese (21)

6 whole grain crackers (2)

8 ounces skim milk (8)

*grams protein in parentheses

 **most protein powders have ~20 grams protein per serving, but check labels

For those not used to thinking in terms of grams of protein (probably most of you), here are a few keys to understanding protein:

  • 1-ounce of beef, pork, fish, poultry, and cheese has about 7 grams of protein. Most of us don’t eat 1-ounce portions of these foods, so if you eat a 5-ounce portion of grilled salmon for dinner, you’ve eaten 35 grams of protein and that doesn’t count the other foods you have with the meal.
  • Dairy foods are rich in protein, the amino acid leucine, as well as other nutrients needed for muscle health such as vitamin D and calcium. 8-ounces (1 cup) of dairy milk has 8 grams of protein, but 8-ounces of ultra-filtered milk, such as Fairlife, has 13 grams of protein. Contrast that with Silk Almond milk that has only 1 gram of protein per serving. The point is that not all “milk” is a rich-protein source.
  • Foods carry a nutrition facts panel that tell you 2 important pieces of information: the serving size is of the food and how many grams of protein are in in one serving. That’s an important thing to keep in mind because you might be eating more than the stated serving size, meaning you are also getting more protein.

legal2

  • I like to look for snacks that are nutrient-rich but not too high in calories. My recent favorite is kefir, a fermented milk drink with 11 grams of protein in 8-ounces, and is rich in probiotics, too.

I reached out the authors (aka, protein gurus) to ask them for a practical take-away from their article.

Meet the gurus

Dr. Stuart Phillips is a professor in the Department of Kinesiology at McMaster University, Hamilton, Canada (follow him on twitter @mackinprof).

“I’d recommend emphasizing the consumption of nutrient-dense sources of high-quality protein like dairy and eggs at meals that are traditionally lower protein: breakfast and lunch. My go-to protein food at breakfast (and sometimes lunch too) is Greek-style yogurt or Icelandic Skyr. Both are cultured dairy, rich in high quality protein, and many other necessary nutrients, and tasty and versatile as a base for berries and nuts.”

Dr. Doug Padden-Jones is a professor in the Department of Nutrition and Metabolism at The University of Texas Medical Branch, Galveston, Texas .

“For generally healthy adults, establish a dietary framework that includes a moderate amount of high-quality protein at each meal. Factors such as energy needs, physical activity, health status, body composition goals, and satiety should be weighed to determine protein needs. But, During periods of  physical disuse (injury, illness, inactivity) middle-age and older adults are at increased risk of muscle/function loss so just meeting the RDA for protein ( 0.8 g protein/kg/day)  is insufficient. Aggressive support with high quality protein (whey /leucine) and activity may help preserve muscle health.”

Dr. Donald Layman is a an emeritus professor in the Department of Food Science and Human Nutrition a the University of Illinois at Urbana-Champaign, Urbana, Illinois. (Follow him on twitter @donlayman).

 “A key for maintaining muscle health as we get older is dietary protein. Surprisingly, adults have higher protein needs than children because we have a continuous need to repair and replace proteins in our body but our efficiency of making new proteins declines with age. The best proteins are meats (including fish), eggs, and dairy. Vegetable proteins are popular, but they always have lower quality than animal proteins. You will need to consume 30% to 50% more total protein if you chose to use plant proteins. So, a 25 g whey protein shake would require at least 35 g of soy protein to be equivalent.” 

 

Dr. Christine Rosenbloom is a registered dietitian nutritionist and a nutrition professor emerita at Georgia State University in Atlanta. Along with Dr. Bob Murray, she is the author of Food & Fitness After 50.

Copyright © 2019 [Christine Rosenbloom]. All Rights Reserved