Animal protein – particularly whey powder – is popularly endorsed as the best source of amino acids for boosting muscle strength. But a closer look at the research suggests that plant proteins could be just as effective for building and maintaining lean muscle mass.
Whey protein contains more of the amino acid leucine than plant proteins. Extensive research shows that leucine activates muscle protein synthesis – i.e. helps muscle to use the protein. This is thought to explain its superior benefits for building lean muscle and strength after resistance training.
However, the evidence derives from studies of whey protein’s short-term impact over 3 to 4 hours. A recent meta-analysis combined nine studies that compared soy protein with various animal proteins over 6 weeks or more (5 studies tested whey and 4 used beef, milk or dairy protein).
Overall, the analysis found that combining protein supplementation with resistance training exercises (bench press and squat) increased muscle strength. But the effects of soy protein did not differ from whey powder or the other animal proteins.
Looking at whole dietary patterns, the Framingham Third Generation Study found last year that people with lower protein intakes had lower lean mass and muscle strength. But they also found no difference between the different types of protein.
According to Health.com, lead author Kelsey Mangano says, “As long as a person is exceeding the recommended daily allowance for protein, no matter the source in their diet, they can improve their muscle health.”
Losing muscle mass is one of the biggest health challenges of aging. Lean muscle does so much more than endow our bodies with a shapely physique.
Older adults need to maintain lean muscle mass to prevent falls, a major problem in aging that results in physical injury, reduced quality of life, and death.
Muscles store glucose to provide energy and can protect against diabetes and heart disease. Age-related loss of muscle mass can lead to sarcopenia, also associated with reduced quality of life, hospital admissions and chronic conditions like poor lung function and breast cancer risk.
Proteins are made from 20 amino acids arranged in thousands of different combinations. Nine amino acids are “essential” – i.e. we need to get them through dietary sources.
Animal proteins include meat, fish, chicken, eggs, and dairy foods. Protein also derives from abundant plant foods including nuts, legumes, seeds, lentils, grains, and even hemp.
Most plant protein sources are incomplete – i.e. they don’t contain all essential amino acids. Proteins derived from animal sources are complete; hence animal protein was deemed to be superior.
However, eating combinations of plant sources provides a complete protein, and it’s now established that the body can store amino acids, so a whole amino acid contingent doesn’t need to be eaten in one meal.
Most importantly, regardless of the source, research suggests that older adults who eat 1 gram of protein per kg of body weight each day are less likely to suffer disability. Combining this with regular physical movement will yield the greatest benefits.
A new study has found that adults over 84 years who eat more protein are less likely to suffer disability, which is a significant problem in this growing age group.
Researchers took food diaries from 722 community-dwelling adults in the UK and measured disability according to difficulty performing daily activities like moving around the house, getting in and out of a chair, shopping, walking and climbing stairs.
Progression of disability, followed up 18 months, 3 and 5 years later, fell into four distinct categories, from very low to severe.
Results showed that adults who ate more protein were less likely to become disabled over the 5-year follow-up than those with lower protein intake, after factoring in gender, education, physical activity, cognition and chronic diseases.
Lead author of the study, Dr Nuno Mendonca, told Nutrition Insight, “We believe that the largest benefit of protein consumption is due to delaying muscle mass and strength loss.”
Protein is critical for maintaining lean muscle mass, needed for strength and mobility, and healthy bone density. Not only that, if protein stores are low, the liver will draw on the muscle’s protein stores to maintain energy levels between meals.
Dietary protein also has a multitude of other important bodily functions including formation of enzymes and hormones, transporting molecules through the bloodstream, manufacturing antibodies and regulating acid-alkaline levels.
Adults in the study who consumed 1g protein per kg of body weight each day were more likely to have lower disability, supporting calls to increase recommended protein intakes.
For a 58 kg person, that could easily be met by eating 2 eggs for breakfast, 100g yoghurt with lunch and a 100g serve of salmon for dinner – all soft foods for people with dentition or swallowing difficulties.
For adults with poor appetite, eating small meals with protein shakes for morning and afternoon tea will help boost protein intake.
It’s important to note that protein needs increase when the body is stressed by infection, burns, cancer or injury.
And to maximise muscle mass and strength, the benefits of regular physical activity in conjunction with protein intake cannot be underestimated.
Protein, an indispensable part of our diet, has multiple roles in the body – particularly in aging for growth, repair and maintaining muscle mass. But dietary proteins are not all equal. Here are some nuts and bolts of this exquisitely complex nutrient.
Protein, carbohydrate and fat are all macronutrients formed by different ratios of carbon, hydrogen and oxygen. Additionally, protein contains nitrogen.
Proteins come in all shapes and sizes. They are created from twenty amino acids joined in fifty to tens of thousands of different combinations to make enzymes, antibodies and hormones, transport molecules and regulate the body’s acid-alkaline balance.
Nine amino acids are essential – the body cannot make them, so they must come from dietary sources. These are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. Six amino acids are conditionally essential (needed in special circumstances like illness) and five are dispensable as the body can synthesise plenty of them.
The biological activity and nutritional benefits of protein vary according to how the amino acids are configured and how the body digests them. Based on this, various methods have been devised to measure protein quality – availability of its amino acids – and digestibility – how the protein is best used.
The biological value (BV) scoring system assumes that protein is the only dietary source of nitrogen. It measures protein quality by calculating a ratio of how much nitrogen is absorbed versus the amount excreted then multiplied by 100 to give a percentage of nitrogen used by the body.
The protein digestibility-corrected amino-acid score (PDCAAS) ranks protein quality by comparing its amino acid profile with a reference score, corrected for faecal nitrogen digestibility. This score was backed jointly by the Food and Agricultural and World Health Organisations (FAO/WHO) in 1989 as the best way to assess protein quality.
But the PDAAS has limitations; for instance measuring amino acid synthesis in the small intestine would be a better assessment of their digestion than in the large bowel (colon). Further analysis has suggested that the PDCAAS tends to underestimate high-quality proteins and overestimate low-quality proteins.
The FAO now recommends the digestible indispensable amino acid score (DIAAS), which measures the digestibility of individual amino acids at the end of the small intestine and may therefore be more accurate.
Despite some variation, the quality ratings generally agree on high protein food sources. Animal protein contains all the essential amino acids and is therefore complete. Eggs and dairy protein are ranked as high-quality proteins, followed by meat, chicken and fish. Eggs and dairy are easily digested and are good options for people with digestive disorders.
Vegetable protein typically lacks one or more amino acids. But the following combinations provide all essential amino acids and are therefore highly ranked: rice and peas; grains and legumes; grains and vegetables; grains, nuts and seeds; legumes, nuts and seeds. Importantly, the body doesn’t necessarily need all amino acids in one meal – they can be spread out over the day.
Some vegetable proteins do contain all essential amino acids. This includes hempseed, pea protein and quinoa.
This is good news in light of mounting research showing the superior health benefits of a plant-based diet. Plant foods provide fibre and nature’s medicinal cabinet of vitamins, minerals and phytonutrients. Concerns over ethics of animal farming and environmental sustainability are also driving a growing demand for diets higher in plant foods.
Cannabis, or marijuana, is the world’s most highly used illicit drug. But hemp – although it derives from the same species – will not cause giggle fits, big toenail fascination or insatiable pizza cravings.
Hempseed contains only negligible amounts of marijuana’s primary psychoactive compound, tetrahydrocannabinol (THC) – and its high concentration of cannabidiol (CBD) counteracts THC’s brain-altering effects.
A diverse, fast-growing plant, hemp is used industrially to make numerous products including paper, canvas, linen, clothing, biodegradable plastics, paint and insulation.
And hempseed – legalised in Australia November last year – has been eaten for thousands of years raw, cooked and roasted. Technically a nut, it is packed with nutrients that include healthy omega-3 and omega-6 fats, vitamin E, minerals, fibre, and protein.
Rivalling whey powder’s 13% protein content, hemp contains 25% protein – more than chia seed and quinoa. Hempseed contains 20 amino acids. That includes the 9 essential peptides that humans need from dietary sources, making it a complete source of plant protein.
The protein is also easily digested, making it highly bioavailable. Its protein digestibility-corrected amino acid score (PDCAAS) is “equal to or greater than certain grains, nuts, and some pulses,” according to researchers from the University of Manitoba.
Research suggests hempseed protein has several health benefits including reduced fatigue and improved immune function. Hempseed protein may also lower blood pressure and cholesterol, indicative of heart health benefits. Its antioxidant properties reduce free radicals responsible for accelerated aging.
In aging, good quality protein itself is important for retaining healthy muscle mass and bone density to reduce risk of sarcopenia and osteoporosis. It can lower risk of falls and improve recovery and wound healing. Protein may even help ward off diabetes and dementia.
Since its legalisation, industry has been creatively devising new products to deliver hemp seeds’ nutritional benefits to consumers – including hemp beer, hemp chocolate and hemp oil. It is also available as a protein powder and flour for baking.
Hempseeds have a nutty flavour. Recipes have sprung up to include them in a smorgasbord of foods ranging from granola, hummus, burgers, pesto, protein balls and chutney to bread, soup and smoothies.
And hemp is not just good for us; it is ecologically sustainable. As well as being fast growing, it does not need much water, so is an ideal crop for Australian conditions. Harry Youngman, Victorian farmer, told the ABC that its “water use efficiency is incredible.”
With its “aggressive rooting structure,” it helps to break up the soil, making it an ideal rotational crop between seasons. Even better, it is weed-resistant and needs little, if any chemicals.