These were among the insights from a group of top nutrition scientists in the United States who this week met for a panel discussion on one of the most perplexing phenomena of the modern-day sustainability conversion: the imbalance of a world which has both massive malnutrition problems and huge amounts of food wastage.

The session was part of the Global Roundtable for Sustainable Beef conference, held in Denver, Colorado, in the US.

Ty Beal, from the Global Alliance for Improved Nutrition in Arizona, said the simple fact was too many people worldwide were malnourished.

Research shows more than 500 million women and adolescent girls have anaemia; one-in-two preschool children and two-in-three women have at least one micronutrient deficiency worldwide, he said.

Nine-in-ten women in several countries in southern Asia and sub-saharan Africa have at least one micronutrient deficiency.

While that number is incredible, possibly more surprising to many of the 250 international delegates at the conference was revelations from recent research which brings to light the fact these deficiencies are also prevalent in the US, the United Kingdom and other high-income countries.

Dr Beal presented findings from studies that show in the UK, one-in-two women have at least one micronutrient deficiency and in the UK and US one-in-five women are iron deficient.

"These numbers are not small and addressing the situation means looking to foods which are the best sources of the nutrients most lacking - iron, zinc, folate, calcium and vitamins B12 and A," he said.

Meat and other animal sourced foods were top sources of commonly lacking nutrients, he said.

However, it was not just the density in those nutrients of animal-sourced foods that needed to be considered, but the bioavailability.

In red meat, the bioavailability ratio of omega 3 fatty acids is 10:1 and for vitamin A it is 12:1, Dr Beal reported.

"For iron, comparing beef to pulses you'll see twice the bioavailability," he said.

"For zinc, it is 70 per cent more."

Meat also contains higher quality protein than most plant foods. The measurement of this is the digestible indispensable amino acid score, and in beef and pork it is higher than other foods - a score of 119 compared to almonds which scores just 40, or chickpeas at 83.

Contrary to popular belief, the populations of many countries are consuming below the mean recommendation of unprocessed red meat, even by Eat Lancet standards, Dr Beal's figures showed

"While it is no surprise that intake is low in most of Africa, what is surprising is that consumption is actually relatively low in high-income countries like the US," he said.

"The narrative often is that consumption of animal-sourced foods, particularly red meat, is very high in these areas. In fact, in high-income countries, it is actually close to the global average and below that in regions like central Asia and Latin America."

About a billion people do not consume enough protein.

"There is a very important role for protein but it is an oversimplification and it does a disservice to protein-rich foods when we label them protein," Dr Beal said.

"The foods themselves have tens of thousands of compounds. There are very large differences in beef compared to lentils or soybeans.

"We need to move as a community away from labelling a food 'protein'."

Nutrition scientist and metabolomics expert Dr Stephan van Vliet, Utah State University, said food policy was informed by tracking only a small number of nutrients but the food matrix contained thousands of unique compounds that impact human metabolism and disease related gene expression.

"In the US, we don't have a protein deficiency but we do have a micro nutrient deficiency," he said.

"We have been looking into whether there are ways we can increase the micro nutrient content of meat and milk through different ways of raising animals.

"We profiled grassfed and grainfed beef in the US and found among grassfed there was a ten fold variation in micronutrient content."

Dr van Vliet also profiled beef against plant based alternatives and found despite very similar nutrition facts panels, there was a 90 per cent difference in metabolic abundances.

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The two were certainly not nutritionally interchangeable, he said.

"These differences can not always be determined from looking at the nutritional facts panel on the packaging," he said.

"This simplistic approach to nutrition, where we have dumbed things down to single nutrients, does not tell the whole story."

At the same time as these diet deficiencies are adding up, the amount of good food that goes to waste is piling up.

According to the Food and Agriculture Organisation of the United Nations, one third of all food produced around the world is wasted.

Meat scientist Brad Morgan, Colorado State University, says that number is growing with labour issues - there are, for example, fruit and vegetable crops around the world not even being harvested.

Research shows 43 per cent of food wastage happens in the home, 40 per cent in restaurants and grocery stores, 16 per cent on farm and two per cent in food manufacturing.

"Such is the problem, there are now states and cities in the US passing food waste laws, areas where folk have to separate organic matter into a certain colour bag and when it is set out on the curb to be picked up, they are charged a fee for the amount of matter they are throwing out," he said.

Meat had not ever had a huge waste factor because it was expensive compared to fruit and vegetables, Dr Morgan said.

"That's not to say it is not wasted - about 20 per cent of the meat we are served on an average basis is discarded."

On average people around the world throw away 614 calories per day.

"Let's be candid, this is embarrassing. I live in one of the poorest counties in Oklahoma and there's a lot of hungry people and still this is happening," Dr Morgan said.

Dr van Vliet made the point that research also indicated that even in Africa, more food was produced than was needed to feed people. In the US, it was about seven times the amount needed, he said.

Enormous work across the supply chain was needed to make nutrition dense foods affordable and accessible across the globe, the panel agreed.

There was a role for government subsidisation but improved trade and transportation would also be critical.

"There is truckload of donated food right there that we just can't get from point a to b," Dr Morgan said.

"We have a shortage of 50,000 truck drivers in the US right now."

And this quandary had to be a part of the climate change and sustainability discussion.

"If global food waste was a country it would be the third largest greenhouse gas emitter after the US and China," Dr Morgan said.