Eating legumes and kale, you will have the same strength as a meat-eater. PICTURE: Supplied

Vegans don't need to worry about bulking up. Their diets are just as effective in protein uptake and maintaining muscle strength, new research suggests.

Protein is known to help muscles grow, but it's been unclear whether it must come from specific food sources. Critics of the ethical diet have long been convinced that those who stick to plant-based foods are missing out on nutrients from meat.

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But scientists have discovered that so long as they eat legumes, nuts and kale, they will have the same strength as a meat-eater.

Researchers from the University of Massachusetts investigated by asking 2,986 men and women questions about their diets. They found that 82 per cent of participants were getting the recommended daily amount of protein.

Their diets fell into one of six patterns: fast food and full fat dairy, fish, red meat, chicken, low fat milk, and legumes.

Muscle mass, strength and bone density were then assessed to see if dietary patterns had an impact. Those who consumed the most protein had the most muscle mass and stronger quadriceps, the muscle in front of the thigh were stronger. The most protein was the equivalent of 126g for a 70kg while the lowest was around 52g.

But the results didn't change based on someone's dietary pattern, the study published in the American Journal of Clinical Nutrition found. Someone getting a large amount of protein from red meat was benefiting as much as a person eating just legumes.

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Study author Dr Kelsey Mangano said: 'High protein diets do benefit most individuals.'It can be beneficial to maintaining muscle mass and strength particularly as we age.' This comes after a study in August suggested swapping meat and eggs for lentils and nuts could add years to someone's life.

Scientists found eating less protein from animal sources such as red meat and dairy products, and increasing plant proteins from cereals, beans and soya, substantially reduced death rates. Mortality from heart disease fell 12 per cent, and deaths from all causes fell by 10 per cent, Massachusetts General Hospital researchers found.