Science in Society Archive

Are Organic Foods More Healthy?

Rhea Gala and Sam Burcher report on new research showing that organic feed gives protection against toxins under vulnerable conditions where conventional feed fails

It has been suggested that organic food contains higher amounts of natural toxic compounds produced by fungi or plants (but see "Increased mycotoxins in organic produce?" this series), whereas conventional food may contain more synthetic toxins from pesticide residues which can also seriously damage human health and the environment. So are there any real health benefits from organic food?

Research reviewed in the Independent Science Panel Report, The Case for a GM-Free Sustainable World (www.indsp.org) has shown that organic crops tend to have a higher nutrient content, and organic feed improves the general health and disease resistance of farm animals. Organic farming practices including the use of animal or green manure and long crop rotation are also thought to reduce plant infection by pathogens. However, mycotoxins (fungus derived toxins) called DON (deoxynivalenol) and OTA (ochratoxin A), often contaminate wheat, whether grown organically or conventionally; they cause cancer, damage genes, and are harmful to the kidneys and the immune system. The levels of these toxins may be reduced by fungicides, or increased by nitrogen fertilisers, and are also influenced by climate and improper storage; for example being kept too hot or wet, a condition that may be associated with organic production.

There have been a few studies showing that animals fed organically have slight improvements over those fed conventionally in mortality rate, body and organ weight, reproductive performance and fertility.

Scientists at the National Institute for Research into Food and Nutrition in Rome have taken a new approach in comparing organic and conventional food consumption, by looking at sensitive markers of cell function in response to the toxins in animals under vulnerable conditions [5]. The markers were the proliferative capacities of lymphocytes found in the intestine and in the spleen, and the acute-phase reaction of the liver, both responding to the presence of the toxins.

The intestinal mucosa (lining) is continuously exposed to millions of food antigens and ingested toxic substances, so the intestinal immune system and the spleen lymphocytes should mount a prompt defence against the insults. The liver acute-phase reaction, responding to disturbances of cell homeostasis (state of balance), will increase the synthesis of some blood plasma proteins and decrease the synthesis of others.

The vulnerable conditions in which body defences can be less efficient are during weaning, and under protein energy malnutrition (PEM). Several studies have shown that PEM induces severe alterations in different organs and tissues including the liver and the immune system, especially during development, causing a predisposition to damage by food contaminants such as DON and OTA.

Weaned rats were assigned to two groups and fed for 30 days on conventional or organic wheat, both of which had been grown under carefully controlled conditions. Both groups were then divided into two subgroups of well-nourished or protein energy malnourished (PEM) rats.

For each rat, lymphocyte proliferation was assayed after stimulating the cells with a mitogen (substance that causes cells to divide) in a culture medium containing either fetal calf serum (FCS) or the rat's own serum (RS) to mimic the in vivo proliferative response. The acute phase proteins - albumin, transthyretin, transferring, ceruloplasmin, retinal-binding protein – were measured in the rat's plasma.

The proliferative response of lymphocytes cultured with FCS, and acute phase proteins showed no difference in organically and conventionally fed rats, under either well-fed or PEM condition; despite the fact that the organic wheat contained higher amounts of mycotoxins, though still lower than that reported to affect immune response.

The proliferative capacity of lymphocytes cultured with the rat's own serum, however, was inhibited in PEM rats on conventional feed compared with those fed organically. This effect was thought to be due to contaminants other than mycotoxins in the conventionally grown wheat.

Thus, conventionally grown wheat represented a higher risk for lymphocyte function than the organically grown wheat, at least, in animals under vulnerable conditions.

In other words, the conventional wheat appeared to compromise the ability of the vulnerable animals to mount an immune response.

Article first published 08/12/04



Sources

  1. Ho MW and Lim LC, et al. The Case for a GM-free Sustainable World, Independent Science Panel Report, ISIS & TWN, London & Penang
  2. Finamore A, Britti MS, Roselli M, Bellovino D, Gaetani S, and Mengheri E. Novel approach for food safety evaluation. Results of a pilot experiment to evaluate organic and conventional foods. J. Agric. Food Chem. 2004. http://pubs3.acs.org/acs/journals/doilookup?in_doi=10.1021/jf049097p

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