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Protein Power: Understanding Animal & Plant Proteins for Optimal Health

If macronutrients were a team, protein would be the all-around MVP. It builds, repairs, regulates, and fuels your body from the inside out—and yet, many people still aren’t getting enough, especially as they age.

In this installment of Demystifying Macros, Micronutrients, and Supplementation, we’re taking a deep dive into protein—where it comes from, what it does, how much you need, and how to choose the best quality sources, whether you're eating animal-based, plant-based, or somewhere in between.

What Is Protein?

Protein is a complex molecule of smaller building blocks called amino acids. There are 20 amino acids your body needs—nine of which are essential, meaning your body cannot synthesize them and must get them through food.

These amino acids serve numerous functions, including:

• Repairing and building muscle tissue
• Supporting immune function
• Producing enzymes and hormones
• Forming skin, hair, nails, and organs
• Contributing to satiety and body composition regulation

Each gram of protein contains four calories, contributing to both structure and energy in the body.

Animal vs. Plant Proteins

Both animal and plant proteins can help meet your daily protein needs, but there are key differences in amino acid composition, absorption, and nutrient density.

Animal Proteins

Examples: chicken, beef, fish, eggs, dairy

• Complete proteins: Contain all nine essential amino acids in optimal ratios
• High bioavailability: Easily digested and absorbed
• Rich in micronutrients: Natural sources of iron, vitamin B12, zinc, and omega-3 fatty acids

A study published in The Journal of Nutrition (2020) showed that animal-based proteins were highly effective in preserving lean mass and strength in older adults, especially when paired with resistance exercise [1].

Plant Proteins

Examples: lentils, beans, tofu, quinoa, seeds

• Often incomplete proteins: Missing one or more essential amino acids
• Can be combined (e.g., rice and beans) to form a complete amino acid profile
• Offer additional benefits: dietary fiber, antioxidants, and phytonutrients

Research from the American Journal of Clinical Nutrition (2015) supports the efficacy of plant proteins in muscle synthesis when consumed in sufficient amounts and in complementary combinations [2].

How Much Protein Do You Need?

The Recommended Dietary Allowance (RDA) for protein is:

• 0.8 grams per kilogram of body weight per day for healthy adults

However, this is the minimum to avoid deficiency—not necessarily the optimal amount for health and performance.

Emerging evidence suggests that:

• Adults aiming for healthy aging, muscle maintenance, or physical performance may benefit from 1.2 to 2.0 grams/kg/day [3]
• Older adults, in particular, need more protein due to anabolic resistance—a reduced sensitivity to protein’s muscle-building effect that comes with aging [4]

For example, a 160-pound (73 kg) adult may need anywhere from 88 to 146 grams of protein daily to optimize lean mass and health outcomes.

Best Whole Food Sources of Protein

Top Animal-Based Sources

• Eggs – 6g per egg
• Chicken breast – 26g per 3 oz
• Greek yogurt – 17g per 6 oz
• Salmon – 22g per 3 oz
• Lean beef – 22g per 3 oz

Top Plant-Based Sources

• Lentils – 18g per cooked cup
• Tempeh – 21g per 4 oz
• Chickpeas – 15g per cooked cup
• Hemp seeds – 10g per 3 tablespoons
• Quinoa – 8g per cooked cup

Pro tip: Include a quality protein source at every meal to help maintain energy levels and support muscle repair throughout the day.

Protein Supplementation: When and Why

While whole foods should remain your primary source, protein supplements can help fill nutritional gaps or enhance performance, especially around workouts or when meals are delayed.

What to Look For in a Supplement

• Whey protein (concentrate or isolate): Fast-digesting, complete amino acid profile, high leucine content
• Plant protein blends (e.g., pea + rice or soy): Effective for muscle recovery, especially when fortified with vitamins like B12
• Minimal added sugar, artificial colors, or fillers

Whey protein has been shown to stimulate muscle protein synthesis effectively, particularly after resistance training [5]. Plant-based options like soy and pea protein can offer comparable benefits when consumed in sufficient quantities [6].

Protein and Aging: A Critical Connection

Muscle loss begins gradually as early as your 30s and accelerates with age, often leading to frailty, reduced mobility, and metabolic decline. This age-related condition, sarcopenia, makes adequate protein intake essential for aging well.

A comprehensive review in Nutrients (2016) emphasized that older adults may benefit from at least 1.2–1.5 g/kg/day of protein, ideally with an even distribution across meals, to preserve muscle function and support longevity [7].

Final Takeaway

Protein is far more than a fitness buzzword—it’s a critical nutrient that powers everything from metabolism to immune health. Whether you’re choosing steak, seeds, tofu, or a post-workout shake, it’s essential to consider quality, quantity, and consistency.

A balanced approach that combines whole food sources with thoughtful supplementation (when needed) ensures that your body gets the amino acids it needs—to build strength, recover efficiently, and age with resilience.

Coming Next:

“Fats: Friend, Foe, or Fuel?”
We’ll uncover the truth about saturated, unsaturated, and essential fatty acids—plus the real deal on cholesterol and cardiovascular health.

References

1. Deutz, N. E. et al. (2014). Protein intake and exercise for optimal muscle function with aging: Recommendations from the ESPEN Expert Group. Clinical Nutrition, 33(6), 929–936.
2. Gorissen, S. H., & Witard, O. C. (2018). Characterising the muscle anabolic potential of dairy, meat, and plant-based protein sources in older adults. Proceedings of the Nutrition Society, 77(1), 20–31.
3. Phillips, S. M. (2016). A brief review of higher dietary protein diets in weight loss: A focus on athletes. Sports Medicine, 46(Suppl 1), 9–13.
4. Bauer, J. et al. (2013). Evidence-based recommendations for optimal dietary protein intake in older people: A position paper from the PROT-AGE Study Group. Journal of the American Medical Directors Association, 14(8), 542–559.
5. Tang, J. E., et al. (2009). Ingestion of whey hydrolysate, casein, or soy protein isolate: Effects on mixed muscle protein synthesis at rest and following resistance exercise in young men. Journal of Applied Physiology, 107(3), 987–992.
6. Messina, M. (2010). Insights gained from 20 years of soy research. The Journal of Nutrition, 140(12), 2289S–2295S.
7. Volpi, E. et al. (2016). Muscle tissue changes with aging. Current Opinion in Clinical Nutrition & Metabolic Care, 19(1), 1–7.