Zinc in Huel and the Effects of Antinutrients

The EU Nutrient Reference Value (NRV) – i.e. the amount that’s recommended as a minimum intake for the population set at a level that covers requirements for most people – for zinc is 10mg for adults^[1]. We need an adequate zinc intake from our diet as this trace element has numerous essential roles in the body including helping some enzymes perform their reactions, and it’s involved in growth and development, as well as the nervous, immune and reproductive systems.

Zinc is essential and too little in our diet will cause problems with growth and development and is associated with neurological or immune disturbances. Zinc deficiency is rare in healthy individuals who consume typical Western diets, although it is more common in vegans^[2].

All the zinc in powdered Huel is naturally occurring from the oats, flaxseed, pea protein and brown rice protein, and no additional has been added.

Zinc and antinutrients

There are substances in foods that inhibit the absorption of some minerals – including zinc – and affect their bioavailability. Bioavailability refers to the amount of a nutrient that is absorbed and goes on to have an effect in the body. These substances that negatively affect absorption of nutrients are known as antinutrients – constituents of food that reduce the nutritional value of other nutrients even though they themselves provide nutritional benefits.

The most notable antinutrient that interferes with the bioavailability of minerals is phytic acid. Phytic acid, also known as inositol hexakisphosphate, is a naturally occurring storage form of phosphorus in plant seeds and the bound form is known as phytate. Oats and flaxseed – two of Huel’s main ingredients – are both rich in phytic acid. Milling grains and removing the bran decreases the amount of phytic acid in a food^[3] and both the oats and flaxseed in Huel are finely milled which significantly lowers the phytic acid content of Huel.

Phytic acid may be an antinutrient, but it’s also a strong antioxidant with health benefits^[4,5,6]. It has been shown to be anticarcinogenic^[7] and can also bind heavy metals (e.g. cadmium, lead) and helps prevent their accumulation in the body^[8].

The extent as to how much phytic acid reduces the bioavailability of zinc varies and other constituents in food affect the rate. Vegans are at risk of not absorbing enough zinc due to the high amounts of phytic acid in a vegan diet, so it’s suggested that their requirements for zinc are 50% higher than those of meat-eaters^{[2, 9]}.

The effect of phytic acid on zinc, whilst significant, is notably less than its effect on iron, and zinc is also not as affected by other antinutrients as other minerals. For instance, calcium can affect the bioavailability of iron but has been shown to have little effect on zinc status in humans^{[10, 11]}.

A European Food Safety Authority (EFSA) Panel looked at the effect of phytic acid on zinc status^[12]. They looked at different levels of phytic acid intake and looked at ranges of zinc requirements from 300mg to 1,200mg of phytic acid per day. They concluded that the Population Reference Intake (PRI) for adult men should be 9.4mg to 16.3mg of zinc per day and for women 7.4mg to 12.7mg per day proportional to the phytic acid intake.

Zinc in Huel

The amount of phytic acid in Huel Powder v3.0 and Black Edition is relatively high and the amount of zinc in 2,000kcal of Huel Powder v3.0/Black Edition is 18/19mg). At 2,000kcal per day, the level of 18mg is more than adequate to cover both male and female requirements.

References

1. Europe FD. Guidance on the Provision of Food Information to Consumers, Regulation (EU) No. 1169/2011. 2013.
2. Trumbo P, et al. Dietary reference intakes: vitamin A, vitamin K, arsenic, boron, chromium, copper, iodine, iron, manganese, molybdenum, nickel, silicon, vanadium, and zinc. J Am Diet Assoc. 2001; 101(3):294-301.
3. Gupta RK, et al. Reduction of phytic acid and enhancement of bioavailable micronutrients in food grains. J Food Sci Technol. 2015; 52(2):676-84.
4. Graf E, et al. Phytic acid. A natural antioxidant. J Biol Chem. 1987; 262(24):11647-50.
5. Hawkins PT, et al. Inhibition of iron-catalysed hydroxyl radical formation by inositol polyphosphates: a possible physiological function for myo-inositol hexakisphosphate. Biochem J. 1993; 294 ( Pt 3):929-34.
6. Phillippy BQ, et al. Antioxidant functions of inositol 1,2,3-trisphosphate and inositol 1,2,3,6-tetrakisphosphate. Free Radic Biol Med. 1997; 22(6):939-46.
7. Shamsuddin A. Anti-cancer function of phytic acid. International Journal of Food Science and Technology. 2002; 37(7):769-82.
8. Schlemmer U, et al. Phytate in foods and significance for humans: food sources, intake, processing, bioavailability, protective role and analysis. Mol Nutr Food Res. 2009; 53 Suppl 2:S330-75.
9. Linus Pauling Institute at Oregon State University. Zinc. Date accessed: 16/07/2020 [Available from: https://lpi.oregonstate.edu/mic/minerals/zinc].
10. McKenna AA, et al. Zinc balance in adolescent females consuming a low- or high-calcium diet. Am J Clin Nutr. 1997; 65(5):1460-4.
11. Hunt JR, et al. Dietary calcium does not exacerbate phytate inhibition of zinc absorption by women from conventional diets. Am J Clin Nutr. 2009; 89(3):839-43.
12. EFSA. Scientific opinion on dietary reference values for zinc. In: Authority EFS, editor. 2014.