The general perception of the plant-forward food lifestyle is positive. But there’s evidence of barriers, including health concerns. So it is important to understand that evidence supports the nutrition adequacy of a whole foods plant-forward way of eating. We observe some deficiencies when energy intake is inadequate – in the vegan diet, compared to varied vegetarian diets, when a diet includes too many ultra-processed foods instead of whole foods.
But generally there is consensus that if a plant-based diet is well planned and supported by supplements, when necessary, people can get the nutrition they need, whatever their age.
Protein, which is made up of amino acids, is essential for growth and maintenance; biochemical reactions (enzymes); as messengers (hormones); for structure (collagen); maintaining proper pH; fluid balance; optimal immunity; for transport and storage (of nutrients); and energy.
Sufficient protein intake from vegetarian diets has long been debated. But recent research suggests that plant foods rich in protein – including legumes, nuts and seeds – can in fact provide enough protein. The 2019 journal article “Dietary Protein and Amino Acids in Vegetarian Diets," concluded that in adults, the “classic vegetarian diets supply more than adequate protein and amino acids.” For children, with proper energy consumption, protein intake from a vegetarian diet is sufficient for growth. But, the article states, “in older people, it could be argued at some vegetarian diets might supply insufficient protein to ensure a long-term nitrogen balance and that some vegetarian meals may provide insufficient protein and leucine to favor postprandial anabolism.” This issue deserves further research. However, the consistent intake of soy products and legumes will supply sufficient protein, as well as other nutrients, for anyone on a plant-forward diet.
Protein intake is insufficient only if a diet does not have sufficient energy or does not include plant-protein-rich legumes, nuts and seeds. And there is no evidence that modestly lower protein intake in vegetarians, compared to those who consume animal foods, has any adverse physiological effects.
According to the Academy for Nutrition and Dietetics, when calorie intakes are adequate, a well-planned plant-forward diet will meet or exceed recommended protein requirements.
N-3 fatty acids
Omega 3 fatty acids – Alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are essential fatty acids associated with cardiovascular health, brain development, reduced inflammation and cognitive health.
According to the Academy for Nutrition and Dietetics, ALA is rich in plant foods, whereas EPA and DHA are rich in animal foods. ALA can be converted endogenously to EPA and DHA, though the process is inefficient and is affected by many factors, including sex, dietary composition, health status and age. High intakes of ALA have been suggested for ideal conversion, but those on an ovo-vegetarian or vegan diet will likely experience deficiency without careful planning, fortified plant-based foods and low-dose algae-based DHA supplements.
Although special attention must be given to those following a dairy-free vegetarian and vegan way of eating, a whole foods plant-forward diet can supply adequate N-3 fatty acid to meet nutrient requirements with guidance from a nutrition or medical professional and careful planning
Iron is necessary for making hemoglobin, the protein in red blood cells that is responsible for carrying oxygen throughout the body. Although about 70 percent of the iron is used for hemoglobin, 25 percent is stored in another blood protein, ferratin, that releases the iron when needed. Roughly 5 percent is found in other essential proteins. Iron is also essential for enzyme function, immune function, thyroid hormone synthesis, and the metabolism of amino acids.
Since iron must be absorbed from what a person eats, it’s essential to make sure dietary choices include iron-rich foods. Heme iron, found in meat, poultry and pork, is easily absorbed by the body, whereas non-heme iron, found in a variety of plant foods, is not. But according to the Academy for Nutrition and Dietetics, non-heme iron comes from a variety of plant-based foods, including fortified whole grains, legumes, nuts, seeds, dried fruits, fortified cereals and green leafy vegetables. And non-heme iron absorption can be increased with vitamin C, so “iron deficiency risk is not higher among plant-based dieters compared with omnivores.”
With careful planning, a whole foods plant-forward diet can supply adequate iron to meet nutrient requirements.
Zinc is a mineral with many essential functions, including as a catalyst for enzymes, immune function, protein and DNA synthesis, wound healing and cell division. It also supports healthy growth and development from pregnancy to adolescence.
Meat and seafood are the richest sources of zinc. Although many plant foods contain zinc, its bioavailability is often lower, because these foods also contain antioxidant compounds called phytates. But the Academy for Nutrition and Dietetics states that though adult vegetarians, compared with non-vegetarians, have similar or somewhat lower dietary zinc intakes, and lower serum zinc concentrations, numbers still fall within the normal range. So “there do not appear to be any adverse health consequences in adult vegetarians that are attributable to a lower zinc status, possibly due to homeostatic mechanisms that allow adults to adapt to a vegetarian diet.”
There are methods to increase zinc absorption for those following a whole foods plant-forward diet, including soaking and sprouting grains, beans, nuts and seeds. Leavening bread can also increase the bioavailability of zinc, and citric acid can aid in absorption. And consumption of some dairy and eggs, plus occasional poultry and seafood, makes that deficiency highly unlikely.
So with careful planning, a whole foods plant-forward diet can deliver adequate zinc to meet nutrient requirements.
Iodine, a trace element naturally present in some foods, is an essential part of thyroid hormones – thyroxine (T4) and triiodothyronine (T3) – that regulate biochemical reactions like protein synthesis and enzymatic reactions. They are also needed for skeletal and nervous system development in the developing fetus and in infants.
A natural and robust source of iodine are sea vegetables such as kelp, nori, kombu and wakame. Other sources include seafood and eggs. In addition, iodine is added to salt and can be found in some enriched food products. That said, iodine deficiency remains a global public health concern in industrialized nations, especially among vegetarians – especially lacto and vegan – who do not consume sea vegetables, iodized salt or iodine-containing supplements. So further monitoring and research is needed to assess iodine status in vegetarians.
But a whole foods plant-forward diet, if well planned, should have adequate iodine.
Calcium, a mineral in the body, is responsible for the structure of bones and teeth. It also plays a critical role in muscle contraction, enzymatic function, blood clotting and normal heart rhythm.
Calcium is present in many foods, but how it is absorbed varies, depending on its source and other variables. According to the Academy for Nutrition and Dietetics, how well the body uses calcium from plant foods relates to oxalate content of foods and to a lesser extent, phytate and fiber. Oxalates and phytates are compounds that interfere with absorption of a vital nutrient. Calcium-rich vegetables, including beet greens, spinach and Swiss chard, are high in oxalates, so the body can’t effectively absorb calcium. Other calcium-rich vegetables – including kale, turnip greens, Chinese cabbage, and bok choy – are low in oxalates, so calcium absorption is higher. The body’s ability to absorb plant-based calcium, whether from foods that naturally contain calcium or from those that are fortified, like tofu and plant milks, can vary.
The academy suggests that whereas calcium intake is adequate among lacto-ovo vegetarians, it is sometimes inadequate for vegans. In those cases, low-dose supplements as prescribed by a qualified nutrition or medical professional are usually needed.
If those are in place, a whole foods plant-forward diet, if well-planned, should meet the daily calcium requirements.
Evidence supports the nutrition adequacy of a whole foods plant-forward way of eating.
Vitamin D, although vitamin D can be found in a few foods, the best source is sunlight, which triggers the body to make it. Vitamin D has many functions, including promoting calcium absorption in the gut to maintain sufficient blood concentrations of both calcium and phosphate, which help with normal bone mineralization and prevent hypocalcemia. It’s also needed for bone growth and bone remodeling, as well as cell growth, neuromuscular and immune function, glucose metabolism and reduction of inflammation.
It's possible to be deficient in vitamin D, even with sun exposure. The risks of sun exposure, as well as insufficient ultraviolet exposure during winter months, can be a problem. So dietary intake, mostly from animal foods such as fatty fish, certain meats, eggs, dairy and fortified foods, is necessary and can be adequate “when considered cumulatively across the diet.” Plants and plant foods, unless fortified, are questionable sources of vitamin D. More research is needed if we are to truly understand the presence of this vitamin and how much of the body can absorb.
A study from 2013 shows that vitamin D intake was sufficient among vegetarian and vegan adults, but likely due to fortification of food products. So the Academy for Nutrition and Dietetics states, “If sun exposure and intake of fortified foods are insufficient to meet needs, vitamin D supplements are recommended.”
So vitamin D status is important to consider for anyone adopting a whole foods plant-based diet, but with careful planning and guidance from a nutrition or medical professional, it’s possible to meet nutrient requirements.
Vitamin B12 is necessary for the development and function of the central nervous system, in addition to healthy red blood cell formation and DNA synthesis. It is also catalyst for enzymes, increasing the rate of reactions in the body. In food, B12 is bound to protein – it must be released before it is absorbed.
B12 is found almost exclusively in animal foods, so those on a vegan diet could likely be deficient if they aren’t consuming enough fermented foods and fortified plant-based foods or taking supplements. Those on a vegetarian diet, whether lacto, ovo or lacto-ovo, must include these reliable plant sources of B12, as well as regular consumption of eggs and dairy, to ensure adequate intake.
With careful planning and guidance from a nutrition or medical professional, most people adopting a whole foods plant-based diet can ensure their nutrient requirements are met.